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MICROCOPY RESOLUTION TEST CHART NATIONAL 8URLlJ or SJANDARD5middot1963middotA

Technical Bulletin No 743 bull Janrwry 1941

middotExperiments with Trichogramma minutum Riley as a Control of the Sugarcane Borer in Louisiana 1

By H A T-IYNES entomoligist and E K BYNUM associate entomologist Division of Cereal and Forage Insect Investigations Bureau of Entomology and Plant Quarantine 2

CONTENTS Page Pace

Introduction ________________________________ _ 1 Experiments with Trichogramma minuum In Early work with Trichoqramma ____ _bullbull ___ bull 2 11the control of the sugarcane borer _________ _

Selection of experimental flelds __________ _ 11Experiments conducted in connection with the Release of parasites ___ bull___ bull___ _ ___ __ _ 13general problem _ bullbull __ bullbull__________ _ 4 Rate of parasitizatiun________________ bull__ _ 17 4 22Overwintering of Trichogramma ____ bullbullbullbullbull _ Dorer-infestation counts _________ _ bullbull ____ _

Dispersal of Trichogramma minulumbullbullbull__ 6 Effect of colonizations on percentage ofmillable cllne _ _______________ ______ 28 Length of time parasitized and non paramiddot

sitlzed egg clusters of the sugarcane borer f~l~ ~~iusgr~~dv~~tFo~ ~liiiicertain 29 remain on plants bullbull _____ bullbullbullbull_bullbullbull__ bull _ fields _______ bull_ __ bull___ bull ____ _ _ ______ _ 36 Relation of actually bored Joints to Joints Summary of experiments conducted in

cooperation with the Louisiana Agriculshyshowing borer Injury externally bullbull _bullbull 8 tural Experiment Station __ bull_____ ______ 39 Relation of rate of parasitization to host Summary and conclusions__ ______________ _ 41

density __ _ __ bull _________ ________ __ 9 Literature cited __ bull_________ __ ______________ 42

~ 9 INTRODUCTION

~ T~ugarcane bOrer (Diatraea saccharalis (F)) causes considerable injuzito sugarcane corn and rice in Louisiana Texas and Florida ~each1ear Losses in sugarcane in Louisiana alone amount to from ~one million to several million dollars annually The egg parasite TricliXigramma mi71utum Riley is an important factor in control of ~ this borer la te in the season Very few or no borer eggs are parasi tized gby tli1- wasp eurly in the season but parasitization increases as the C seasorrlldvances a~d by harvest time nearly all borer eggs have becomeltparasi tized VariQus efforts have been made to increase the uscfulshyCD ness of this parasi~c by increasing its numbers in the field early in thej spason I

I Received for publication April 17 19-10 Thl) writers are indebted to W lI Larrimer in charge of the Diisi~n of Cereal and Fora~() Insect Invesshy

tigations in 1933 to P X Annand in charge of this Oiision from that year to September 1937 and tfrI W Ingram in charge of sugarcane and rice insec~ Investigations in the Division for sug~estions Ilnd criticism made during thl) course of these experiments and in the preparation of the manuscript They herehyacknowledge the coop(ration of the owners managers and oversetrs of the arious plantations on which the experiments were conductNI Rnd the ossistance rtndlreti by W E Unlry Leon J Chnrpentier WhitneyKrepper and others in making egg collections and Infestation counts and in obtaining Ield data

1

2 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

A large number of publications deal with the different methods of rearing Trichogramma mirutum and with experiments in mass liberashytions as a control for a great variety of insect pests As there have been so many conflicting reports on the success of mass liberations of Trichogramma to control various insects and since it has been stated that losses from the sugarcane borer in Louisiana could be greatly reduced by mass liberations of this parasite it was decided to conduct a series of experiments in Louisiana to obtain further information on the value of this practice The results of these experiments 3 are reported in this bulletin

EARLY WORK WITH TRICHOGRAMMA

In 1921 Oleare (3)4 in British Guiana first began the breeding of Trichogramma on a large scale for field liberations in sugarcane fields He stored borer-infested shoots (dead hearts) in an insectary and reared Trichogramma adults from the eggs deposited by the moths emerging from these shoots As many as 35000 Trichogramma per day were liberated during a period of 3 months on one sugarcane estate This practice was regarded with much favor at first but Oleare (4) later stated that more recent investigations by Myers had shown the inadequacy of this method of control

In 1926 Flanders (5) experimented with laboratory rearing of Trichogrcmma on various host eggs and found the Angoumois grain moth (Sitotroga cerealella (Olivraquo to be well adapted to quantity production of Trichogmmma

Hinds and Spencer (8 9) were the first to apply Flanders methods of rearing Trichogramma on eggs of Sitotroga to the control of the sugarcane borer by mass liberations of the parasite They reported a marked increase in parasitization in 1927 1928 and 1929 in canefields where Trichogramma had been released and reported borer control in certain fields on one plantation in 1929

After six seasons work in experimental control of the sugarcane borer by Trichogramma liberations Hinds Osterberger and Dugas (6) reported as follows

Trichogramma colonization tests as made in fields of corn and sugar cane in Louisiana during the seasons of 192i to 1932 have shown consistently beneficial results in the rapid increase following in the rate and proportion of borer eggs destroyed They have shown consistent and regularly proportional decreases in borer damage as measured by the percentages of joints bored the number of emergence holes found and the moth population produced per acre They have shown regularly a very substantial increase in the number of miIIable stalks produced amounting to about 6000 per acre The corre~ponding increase in the weight of miIlable cane has amounted to more than three tons per acre With this there has been fonnd an average increase of over 20 Ibs of sugar per ton of cane produced in protected areas This does not mean complete control of the borer and never wiIl-but it appears to show one practicable easily usable and very dependable and profitable method which may be used in decreasing borer damage in Louisiana

Tucker (16) in 1935 reporting on 6 years work ith Trichogramma releases in Barbados as a control for Diatraea saccharalis stated that

Whilst an adequate statistical proof of increased general and averageshyparasitism may not have been obtained there is a definite indication that the

In 1933 the experiments were conducted undEr tbe di~ction of H II Jaynes frQm th~ Houma laboratoryIn 1934 and 1935 the Jean~rette aurl Houma experiments were conduct(c as Stparate units with Mr Jaynesresponsible for the experiments at Jeanerette and E K Bynum for those at Houma During these 2 years the experiments were under the direction o( J W Tnllam in charge o( sugarcane and rice insect Inv~stigashytions who wno responsible (or outlinin and coordinating the work

bull Italic figures In parentheses refer to Literature Cited p 42

3 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

early mass releases of parasites each year achieve their purpose of increasing this mortality in a manner which results in a measurable decrease in the number of effective borers which survived over the period of liberation and therefore of the final damagl to the crop

Smyth (15) reporting on the technique in the mass production of Trichogramma used to control the cane borer in Peru says

Significant is the fact that as a result of mass colonizations of Trichogramma wasps reared by this technique borer damage was so reduced that the purity and sucrose of the cane (and hence the sugar content) showed a very considerable increase in a large series of fields colonized with parasites over those registered in other fields of the same plantation not so colonized

Mass liberations of Trichogramma have been tried as a control for insects other than the sugarcane borer Peterson (12) in 1930 in experimenting with Trichogramma as a control for the oriental fruit moth (Grapholitha molesta (Busck)) reported

Preliminary field tests in a peach orchard indicate that small liberations of from 300 to 1000 adults per tree are not sufficient to produce parasitism among eggs in adjacent trees

Allen and Warren (1) working with the same insect reported in 1932 at the end of 2 years of investigations that the increased proshyduction of fruit did not justify the added expense The releases were made at the rate of 55000 parasites per acre during each of the two seasons Schread and Garman (14) also experimenting with the release of Trichogramma as a control for the oriental fruit moth reported in 1933 as follows

The average percentage parasitism in 1931 in three orchards where no Trishychoflramma were liberated Wll~ 23 in those orchards where they were liberated it wa 45 percent Observations and field counts indicated that high Trichogramma parasitism was correlated with reduced infestation but the reducshytion was not enough in some cases to be called comtlercial control

List and Davis (11) conducted experiments for 2 years with Trishychogral7lma minutum as a control for the codling moth (CalpOCap8a pomo1~la (L)) and in 1932 made the following statement regarding the results of their experiments

They indicate that during seasons of high natural parasitilm little is accomshyplished by either mass liberations or by colonization of Trichoflramma During seasons of low natural parasitism liberations can be responsible for 0 pronounced parasitism but in no case bas this becn sufficient to show a marked control of the codling moth as indicated by fruit examinations

Schread (13) carried on some cooperative experiments ith A W Morrill and the Associated Sled Growers of Milford to determine the value of releasing Trichogramma for the control of the European corn borer (Pyrausta n-ubilalis (Hbn)) and reported after parasite release at the rate of 10000 20000 and 30000 per acre that

Data accumulated throughout the season wcre not significant from the standshypoint of colonization The averagc parasitism in thc adjacent areas was slightly higher than in thc colonized areas whereas during tbe second brood the results were thc reverse In tbe check plots the average para~iti~m rlurinp the second brood was approximately five times as great as found i~ the colonized areas

Clausrn (2) made thr following statement in 1935 about the liberashytion of Trichogramma as a control for insect pests

In recent years efforts have been made to extend the usefulness of this parasite by rearing the SP( in enormOUR numbers upon grain moth eggs and liberating them in the infestd fields and orchards early in the season This has been tripd on a number of important pests of field crops and orchard trees but the reultB

4 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

thus far have not been conclusive This work is still in the experimental stage and at present it is not recommended to growers as a field prautice

EXPERIMENTS CONDUCTED IN CONNECTION WITH THE GENERAL PROBLEM

In investigating the value of releases of Trichogramma minutum it was found desirable to obtain all information that would be useful in interpreting the data or that would shed additional light on the probshylem The results of these related investigations are given first

OVERWINTERING OF TRICHOGRAMMA

Very little is known about how or where Trichogramma minutum passes the linter months in Louisiana No Diatraea eggs are availshyable from harvest time in the fall until the moths emerge from the overwintered borer larvae in the g~ring a period of from 3 to 5 months Parasitized eggs of Diatraea that have been collected in the fall and kept under the temperatures prevailing at the time have always proshyduced adult~ of Trichogramma within a comparatively short period It seems unlikely that Trichogramma adults hibernate from the faU to the spring as there are days and periods of days during the winter warm enough for adult activity It seems reasonab7Le to assume that mating and egg deposition take place in the field during these warm days as is the case in the laboratory

In an attempt to determine what environments are most conducive to Trichogramma survival over the winter Sitotrola eggs were placed in the field from the lotter part of January through to the middle of May 1933 to determine whether they would be parasitized From 100 to 300 or more eggs were posted on a small piece of cardboard These cardboards were placed in a field in sets of 8 each card being fastened to a small stake and protected from the direct sunlight by a shingle attached to the stake They were put out every 2 weeks and were placed in 4 fields of cane 1 alfalfa field 2 cabbage fields and 1 turnip field 1 wooded swamp and 2 corncribs None of these eggs ever showed signs of parasitization

Searches were made during the winter for eggs of various insects but none of those found had been paratitized by Trichogramma alshythough a live adult of Trichogramma was taken on a mllstardleaf in a small plot at the Houma laboratory on February 5 1934

During the third week in May 1934 16 stakes were so placed that 1 was at the edge of a wood then 1 cnry 100 feet along rows of corn up to 1000 feet then 1 stake (very 200 feet along a row of cane ~n~kshying the last stake 2000 feet from the woods Cardboards ronbunmg bagworm eggs vere placed on these stakes but none werc parasitizEd

It was not knovn what speci(s of eggs might bE available in nature as host material for Triclwgramma during th( winter and (ilrly in the spring As it was v(ry difficult to locate fggs in any nllmb(r that mio-ht be subject to parasitization a few bait traps wer( used (I1ch yer durinO certain periods of the vinter and earlv spring months to obtain a c~llection of the various moths that might be laying eggs that would possibly srrve as hosts A solution of corn sirup and water (1 to 9 plrts) with veast WilS lIs(d as ii bait On iIilrch 20 1933 10 traps were plilcecl50 feet apart along a ditch in iI canefield

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 5

at Houma These traps were removed on April 30 During this period only 185 moths were caught

On February 22 1934 6 traps were placed around an old garden patch that was somewhat overgrown with weeds and brush near an old oak tree at Jeanerette Four other traps were placed between a canefield and a pecan orchard at the same time During the first 15 days 493 moths were caught A new solution was placed in them on March 15 but only 110 moths were taken during the next 15 days The traps near the old garden patch caught many more moths than those alongside the canefield Eggs were obtained from 76 of the moths and adults of Trichogramma minutum were put with some of these eggs Eggs from 22 different individuals were parasitized

Bait traps were again set out at Jeanerette on Janual1J 12 1935 Flve of these traps were placed 100 feet apart along a ditch between two cuts of stubble cane on Albania Plantation The field was surshyrounded by other canefields The other five traps were placed in the woo~s in back of Albania Plantation The first trap was about 230 feet m from the edge of the woods and the others were at 100~foot intervals

Collections of moths were made for 5 days The traps were refilled and collections were made at two later periods The results of the collections are listed in table 1

T~BLE I-Bail-trap collection of moths (all species) at Jeanerette La 1985

Moths collected In-Collection period

Canefield Woods

NUmbtr Number Jan 13-17bullbull _ ______ ___ 171 62 Jan 27-Feb 2_ 9 15 Feb 12-16_ 187 229

TotaL___ 367 306

Out of the 673 moths collected in 1935 129 females deposited eggs in the laboratory Eighty of these females were from the traps in the canefield By exposing these eggs to Trichogramma parasitization was obtained on eggs from 53 different individuals Eggs of 33 of 49 females collected in the woods were also parasitized

Since the moths hftve not been identified the number of species collected which species deposit eggs that are readily parasitized and which deposit eggs not readily parasitized am not yet known Cermiddotmiddot tain species deposited a layer of hairs over the egg cluster and these eggs were seldom parasitized by Trichogramma

It may be noted that there was a considerable difference in the number of moths collected during the three periods of exposure in 1935 It is probable that this difference was due at least in part to variations in temperature The first killing frosts occurred on December 11 and 12 when the minimum temperatures were 26deg and 21 0 F respectively This temperature no doubt killed some of the adult moths present but it did not kill many of the larvae and pupae as a fair number of moths were collected from January 13 to 17 a month after the freeze The second cold spell came between January 22 and 25 when a minimum temperature of 190 was reached This low temperature proha bly

6 TECHJlJCAL BULLETIN 743 U S DEPT OF AGRICULTURE

killed a number of the moths present and very few were collected from January 27 to February 2 lltIoths either were few or else not active as the temperature during this period was lower than during either of the two other collection periods By the time of the third collecshytion however February 12-16 moths were very abundant

Owing to the greater protectbn offered moths it was thought that more eggs might be available for parasitization in the woods during the winter than in the more exposed canefields This may be the case as the moths may go to the woods to deposit their eggs but the moths were apparently as abundant in the canefields as in the woods These collections indicate very clearly that a number of lepidopterous eggs are being laid during the winter and early spring months that could serve as host eggs for Trichogramma minutum

DSPERSAL OF TRICHOGRAMMA lUINUTUl[

Experiments to determine the natural spread of Trichogramma in canefields were carried on in 1933 and 1934 the first year at Houma and the second at Jeanerette

In 1933 2 groups of 56 stakes each were arranged with 8 at 25 feet from the center and 16 each at 50 75 and 100 feet from the center Cards of fresh Sitotroga eggs were placed at ll height of IX feet on all the stakes and additional cards of Sitotroga eggs were placed at a height of 5X feet on 8 of the stakes in each group at the cardinal points of the compass Reference to cards on these 8 stakes will 11ave the additional notation in parentheses as to whether the high or low card is referred to Trichogramma adults were released in the center of 1 group of 8takes The other group which was 740 feet away (center to center) served as a check

As before the cards were protected from the sun by a small shingle Ten sets of cards were used during the period of 13 days on both the release and the check group of stakes Some 75000 Trichogramma adults were released at the center of 1 group of stakes on April 11 just after the first set of cards had bepn placed on the stakes at 8 a m There was a fairly strong wind from the NNW The cards were collected the liext morning and later showed parasitization to have occurred at 25 feet SE j at 50 feet SE SSE and NNW and at 75 feet SSE There Vas no parasitization on the cards from the check group The second set of cards from the release group showed no signs of parasitization but in the check group which was 740 feet directly east of the release group parasitization occurred at 25 feet NW and 100 feet SE from the center of the check group of stakes

On April 13 80000 more Trichogramma were released Cards put out just before this release and left for 48 hours showed parasitization at the following points 25 feet NW W SE and NE 50 feet at WNW N (low) E (low) and NE No parasitization appeared in the check group There was a rainfall of 045 inch between April 13 and 14 Oards for the next 48 hours showed parasitization at 25 feet N Ilnd 50 feet E (low) No parasitization developed in the check group for this set or in any of the later sets

No further parasitization was obtained in the release l0UP until the last set exposed from g a m April 23 to 9 a m April 24 when parasitization occurred at 50 feet E (high) W (high) and WSW The weather during this period was not favorable but thC Cxperiment

EXPERDIEXTIi FOR COXTROL OF SUGARCAXE BORER 7

showed that the parasites spread at least 50 to 75 feet within a few hours after release apparently by drifting with the wind which was smiting

In 1934 2 groups of 40 stakes were arranged with 8 each at 25 50 and 7fi feet from the center and 16 at 100 feet from the center Cards were placed at a height of 1~ feet on all stakes and additional ones as in 1933 were placed at a height of 5~ feet on 8 of them Cards containing fresh bagworm eggs were placed on these stakes and were protected from the sun by small shingles Six sets of cards were used during the period of 9 days The center of the check stakes was 1200 feet west of the point where the releases were made Approximately 40000 Trichogramma adults were released on April 26 and another 40000 were released on April 27 at the center of the test group

No parasitization was obtained on any of the cards of the six sets placed on the check stakes No parasitization was obtained from the first set in the release area which was exposed from April 26 to 27 In the eecond set parasitization was obtained on seven different cards as follows At 25 feet SE at 50 feet SE S (low) N (high) and N (low) j and at 100 feet E (low) and E (high) On April 26 the wind wa first from the southeast then later a fairly strong wind blew from directly south On April 27 a slight breeze was from the southwest On April 28 there was a fair breeze from the north In the third set parasitization was obtained at 25 feet RE and at 50 feet S (high) In the fourth sd parasitization occurred only at 25 feet S and in the fifth set only at 50 feet S (high) A large number of Trichogramma were still on the center stake on May 1 Parasitizashytion was obtained in the sixth set on five cards all at 50 feet E (high) SE S (high) S (low) and N (low)

On several of the cards all the eggs had been eaten by spidrs ants beetles and other pests although all the stakes had a good band of a sticky material around them just above the surface of the ground No rain fell during this period except for a slight sprinkle on May 2 when the sixth set of cards was being put out

It may be noted that parasitization was obtained as far as 100 feet from the release point within 48 hours after the first release of Irichogramma This agrees very closely with the results of the previous year when parasitization occurred at 25 50 and 75 feet within the first 24 hours after release

These experiments were conducted in April rather than later in the season to minimize interference by parasites already present in the field At the time parasites are being released for control purshyposes the cane is higher and dispersal may vary from that found at these earlier dates

LENGTH OF TOlE P-RASITIZED AND NONPRASITIZED EGG CLUSTERS OF

THE SUGAHCANE BOHEH REMAIN ON PLANTS

To determine the rrlative lenlth of time parasitized and nonshyparasitizrd Pgg clustprs remain on plants and ther(ny the reliabili1iY of counts includillg enwrgecl or hatched ltgg clusters lOS freshly laid borer egg clusters were located and marked on corn and cane at Jeanerette between July 12 and 19 1934 The Illajority of these were on corn These clusters were examined as often as possible until August 14 when other work prevented further obsen~ations One

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

2 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

A large number of publications deal with the different methods of rearing Trichogramma mirutum and with experiments in mass liberashytions as a control for a great variety of insect pests As there have been so many conflicting reports on the success of mass liberations of Trichogramma to control various insects and since it has been stated that losses from the sugarcane borer in Louisiana could be greatly reduced by mass liberations of this parasite it was decided to conduct a series of experiments in Louisiana to obtain further information on the value of this practice The results of these experiments 3 are reported in this bulletin

EARLY WORK WITH TRICHOGRAMMA

In 1921 Oleare (3)4 in British Guiana first began the breeding of Trichogramma on a large scale for field liberations in sugarcane fields He stored borer-infested shoots (dead hearts) in an insectary and reared Trichogramma adults from the eggs deposited by the moths emerging from these shoots As many as 35000 Trichogramma per day were liberated during a period of 3 months on one sugarcane estate This practice was regarded with much favor at first but Oleare (4) later stated that more recent investigations by Myers had shown the inadequacy of this method of control

In 1926 Flanders (5) experimented with laboratory rearing of Trichogrcmma on various host eggs and found the Angoumois grain moth (Sitotroga cerealella (Olivraquo to be well adapted to quantity production of Trichogmmma

Hinds and Spencer (8 9) were the first to apply Flanders methods of rearing Trichogramma on eggs of Sitotroga to the control of the sugarcane borer by mass liberations of the parasite They reported a marked increase in parasitization in 1927 1928 and 1929 in canefields where Trichogramma had been released and reported borer control in certain fields on one plantation in 1929

After six seasons work in experimental control of the sugarcane borer by Trichogramma liberations Hinds Osterberger and Dugas (6) reported as follows

Trichogramma colonization tests as made in fields of corn and sugar cane in Louisiana during the seasons of 192i to 1932 have shown consistently beneficial results in the rapid increase following in the rate and proportion of borer eggs destroyed They have shown consistent and regularly proportional decreases in borer damage as measured by the percentages of joints bored the number of emergence holes found and the moth population produced per acre They have shown regularly a very substantial increase in the number of miIIable stalks produced amounting to about 6000 per acre The corre~ponding increase in the weight of miIlable cane has amounted to more than three tons per acre With this there has been fonnd an average increase of over 20 Ibs of sugar per ton of cane produced in protected areas This does not mean complete control of the borer and never wiIl-but it appears to show one practicable easily usable and very dependable and profitable method which may be used in decreasing borer damage in Louisiana

Tucker (16) in 1935 reporting on 6 years work ith Trichogramma releases in Barbados as a control for Diatraea saccharalis stated that

Whilst an adequate statistical proof of increased general and averageshyparasitism may not have been obtained there is a definite indication that the

In 1933 the experiments were conducted undEr tbe di~ction of H II Jaynes frQm th~ Houma laboratoryIn 1934 and 1935 the Jean~rette aurl Houma experiments were conduct(c as Stparate units with Mr Jaynesresponsible for the experiments at Jeanerette and E K Bynum for those at Houma During these 2 years the experiments were under the direction o( J W Tnllam in charge o( sugarcane and rice insect Inv~stigashytions who wno responsible (or outlinin and coordinating the work

bull Italic figures In parentheses refer to Literature Cited p 42

3 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

early mass releases of parasites each year achieve their purpose of increasing this mortality in a manner which results in a measurable decrease in the number of effective borers which survived over the period of liberation and therefore of the final damagl to the crop

Smyth (15) reporting on the technique in the mass production of Trichogramma used to control the cane borer in Peru says

Significant is the fact that as a result of mass colonizations of Trichogramma wasps reared by this technique borer damage was so reduced that the purity and sucrose of the cane (and hence the sugar content) showed a very considerable increase in a large series of fields colonized with parasites over those registered in other fields of the same plantation not so colonized

Mass liberations of Trichogramma have been tried as a control for insects other than the sugarcane borer Peterson (12) in 1930 in experimenting with Trichogramma as a control for the oriental fruit moth (Grapholitha molesta (Busck)) reported

Preliminary field tests in a peach orchard indicate that small liberations of from 300 to 1000 adults per tree are not sufficient to produce parasitism among eggs in adjacent trees

Allen and Warren (1) working with the same insect reported in 1932 at the end of 2 years of investigations that the increased proshyduction of fruit did not justify the added expense The releases were made at the rate of 55000 parasites per acre during each of the two seasons Schread and Garman (14) also experimenting with the release of Trichogramma as a control for the oriental fruit moth reported in 1933 as follows

The average percentage parasitism in 1931 in three orchards where no Trishychoflramma were liberated Wll~ 23 in those orchards where they were liberated it wa 45 percent Observations and field counts indicated that high Trichogramma parasitism was correlated with reduced infestation but the reducshytion was not enough in some cases to be called comtlercial control

List and Davis (11) conducted experiments for 2 years with Trishychogral7lma minutum as a control for the codling moth (CalpOCap8a pomo1~la (L)) and in 1932 made the following statement regarding the results of their experiments

They indicate that during seasons of high natural parasitilm little is accomshyplished by either mass liberations or by colonization of Trichoflramma During seasons of low natural parasitism liberations can be responsible for 0 pronounced parasitism but in no case bas this becn sufficient to show a marked control of the codling moth as indicated by fruit examinations

Schread (13) carried on some cooperative experiments ith A W Morrill and the Associated Sled Growers of Milford to determine the value of releasing Trichogramma for the control of the European corn borer (Pyrausta n-ubilalis (Hbn)) and reported after parasite release at the rate of 10000 20000 and 30000 per acre that

Data accumulated throughout the season wcre not significant from the standshypoint of colonization The averagc parasitism in thc adjacent areas was slightly higher than in thc colonized areas whereas during tbe second brood the results were thc reverse In tbe check plots the average para~iti~m rlurinp the second brood was approximately five times as great as found i~ the colonized areas

Clausrn (2) made thr following statement in 1935 about the liberashytion of Trichogramma as a control for insect pests

In recent years efforts have been made to extend the usefulness of this parasite by rearing the SP( in enormOUR numbers upon grain moth eggs and liberating them in the infestd fields and orchards early in the season This has been tripd on a number of important pests of field crops and orchard trees but the reultB

4 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

thus far have not been conclusive This work is still in the experimental stage and at present it is not recommended to growers as a field prautice

EXPERIMENTS CONDUCTED IN CONNECTION WITH THE GENERAL PROBLEM

In investigating the value of releases of Trichogramma minutum it was found desirable to obtain all information that would be useful in interpreting the data or that would shed additional light on the probshylem The results of these related investigations are given first

OVERWINTERING OF TRICHOGRAMMA

Very little is known about how or where Trichogramma minutum passes the linter months in Louisiana No Diatraea eggs are availshyable from harvest time in the fall until the moths emerge from the overwintered borer larvae in the g~ring a period of from 3 to 5 months Parasitized eggs of Diatraea that have been collected in the fall and kept under the temperatures prevailing at the time have always proshyduced adult~ of Trichogramma within a comparatively short period It seems unlikely that Trichogramma adults hibernate from the faU to the spring as there are days and periods of days during the winter warm enough for adult activity It seems reasonab7Le to assume that mating and egg deposition take place in the field during these warm days as is the case in the laboratory

In an attempt to determine what environments are most conducive to Trichogramma survival over the winter Sitotrola eggs were placed in the field from the lotter part of January through to the middle of May 1933 to determine whether they would be parasitized From 100 to 300 or more eggs were posted on a small piece of cardboard These cardboards were placed in a field in sets of 8 each card being fastened to a small stake and protected from the direct sunlight by a shingle attached to the stake They were put out every 2 weeks and were placed in 4 fields of cane 1 alfalfa field 2 cabbage fields and 1 turnip field 1 wooded swamp and 2 corncribs None of these eggs ever showed signs of parasitization

Searches were made during the winter for eggs of various insects but none of those found had been paratitized by Trichogramma alshythough a live adult of Trichogramma was taken on a mllstardleaf in a small plot at the Houma laboratory on February 5 1934

During the third week in May 1934 16 stakes were so placed that 1 was at the edge of a wood then 1 cnry 100 feet along rows of corn up to 1000 feet then 1 stake (very 200 feet along a row of cane ~n~kshying the last stake 2000 feet from the woods Cardboards ronbunmg bagworm eggs vere placed on these stakes but none werc parasitizEd

It was not knovn what speci(s of eggs might bE available in nature as host material for Triclwgramma during th( winter and (ilrly in the spring As it was v(ry difficult to locate fggs in any nllmb(r that mio-ht be subject to parasitization a few bait traps wer( used (I1ch yer durinO certain periods of the vinter and earlv spring months to obtain a c~llection of the various moths that might be laying eggs that would possibly srrve as hosts A solution of corn sirup and water (1 to 9 plrts) with veast WilS lIs(d as ii bait On iIilrch 20 1933 10 traps were plilcecl50 feet apart along a ditch in iI canefield

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 5

at Houma These traps were removed on April 30 During this period only 185 moths were caught

On February 22 1934 6 traps were placed around an old garden patch that was somewhat overgrown with weeds and brush near an old oak tree at Jeanerette Four other traps were placed between a canefield and a pecan orchard at the same time During the first 15 days 493 moths were caught A new solution was placed in them on March 15 but only 110 moths were taken during the next 15 days The traps near the old garden patch caught many more moths than those alongside the canefield Eggs were obtained from 76 of the moths and adults of Trichogramma minutum were put with some of these eggs Eggs from 22 different individuals were parasitized

Bait traps were again set out at Jeanerette on Janual1J 12 1935 Flve of these traps were placed 100 feet apart along a ditch between two cuts of stubble cane on Albania Plantation The field was surshyrounded by other canefields The other five traps were placed in the woo~s in back of Albania Plantation The first trap was about 230 feet m from the edge of the woods and the others were at 100~foot intervals

Collections of moths were made for 5 days The traps were refilled and collections were made at two later periods The results of the collections are listed in table 1

T~BLE I-Bail-trap collection of moths (all species) at Jeanerette La 1985

Moths collected In-Collection period

Canefield Woods

NUmbtr Number Jan 13-17bullbull _ ______ ___ 171 62 Jan 27-Feb 2_ 9 15 Feb 12-16_ 187 229

TotaL___ 367 306

Out of the 673 moths collected in 1935 129 females deposited eggs in the laboratory Eighty of these females were from the traps in the canefield By exposing these eggs to Trichogramma parasitization was obtained on eggs from 53 different individuals Eggs of 33 of 49 females collected in the woods were also parasitized

Since the moths hftve not been identified the number of species collected which species deposit eggs that are readily parasitized and which deposit eggs not readily parasitized am not yet known Cermiddotmiddot tain species deposited a layer of hairs over the egg cluster and these eggs were seldom parasitized by Trichogramma

It may be noted that there was a considerable difference in the number of moths collected during the three periods of exposure in 1935 It is probable that this difference was due at least in part to variations in temperature The first killing frosts occurred on December 11 and 12 when the minimum temperatures were 26deg and 21 0 F respectively This temperature no doubt killed some of the adult moths present but it did not kill many of the larvae and pupae as a fair number of moths were collected from January 13 to 17 a month after the freeze The second cold spell came between January 22 and 25 when a minimum temperature of 190 was reached This low temperature proha bly

6 TECHJlJCAL BULLETIN 743 U S DEPT OF AGRICULTURE

killed a number of the moths present and very few were collected from January 27 to February 2 lltIoths either were few or else not active as the temperature during this period was lower than during either of the two other collection periods By the time of the third collecshytion however February 12-16 moths were very abundant

Owing to the greater protectbn offered moths it was thought that more eggs might be available for parasitization in the woods during the winter than in the more exposed canefields This may be the case as the moths may go to the woods to deposit their eggs but the moths were apparently as abundant in the canefields as in the woods These collections indicate very clearly that a number of lepidopterous eggs are being laid during the winter and early spring months that could serve as host eggs for Trichogramma minutum

DSPERSAL OF TRICHOGRAMMA lUINUTUl[

Experiments to determine the natural spread of Trichogramma in canefields were carried on in 1933 and 1934 the first year at Houma and the second at Jeanerette

In 1933 2 groups of 56 stakes each were arranged with 8 at 25 feet from the center and 16 each at 50 75 and 100 feet from the center Cards of fresh Sitotroga eggs were placed at ll height of IX feet on all the stakes and additional cards of Sitotroga eggs were placed at a height of 5X feet on 8 of the stakes in each group at the cardinal points of the compass Reference to cards on these 8 stakes will 11ave the additional notation in parentheses as to whether the high or low card is referred to Trichogramma adults were released in the center of 1 group of 8takes The other group which was 740 feet away (center to center) served as a check

As before the cards were protected from the sun by a small shingle Ten sets of cards were used during the period of 13 days on both the release and the check group of stakes Some 75000 Trichogramma adults were released at the center of 1 group of stakes on April 11 just after the first set of cards had bepn placed on the stakes at 8 a m There was a fairly strong wind from the NNW The cards were collected the liext morning and later showed parasitization to have occurred at 25 feet SE j at 50 feet SE SSE and NNW and at 75 feet SSE There Vas no parasitization on the cards from the check group The second set of cards from the release group showed no signs of parasitization but in the check group which was 740 feet directly east of the release group parasitization occurred at 25 feet NW and 100 feet SE from the center of the check group of stakes

On April 13 80000 more Trichogramma were released Cards put out just before this release and left for 48 hours showed parasitization at the following points 25 feet NW W SE and NE 50 feet at WNW N (low) E (low) and NE No parasitization appeared in the check group There was a rainfall of 045 inch between April 13 and 14 Oards for the next 48 hours showed parasitization at 25 feet N Ilnd 50 feet E (low) No parasitization developed in the check group for this set or in any of the later sets

No further parasitization was obtained in the release l0UP until the last set exposed from g a m April 23 to 9 a m April 24 when parasitization occurred at 50 feet E (high) W (high) and WSW The weather during this period was not favorable but thC Cxperiment

EXPERDIEXTIi FOR COXTROL OF SUGARCAXE BORER 7

showed that the parasites spread at least 50 to 75 feet within a few hours after release apparently by drifting with the wind which was smiting

In 1934 2 groups of 40 stakes were arranged with 8 each at 25 50 and 7fi feet from the center and 16 at 100 feet from the center Cards were placed at a height of 1~ feet on all stakes and additional ones as in 1933 were placed at a height of 5~ feet on 8 of them Cards containing fresh bagworm eggs were placed on these stakes and were protected from the sun by small shingles Six sets of cards were used during the period of 9 days The center of the check stakes was 1200 feet west of the point where the releases were made Approximately 40000 Trichogramma adults were released on April 26 and another 40000 were released on April 27 at the center of the test group

No parasitization was obtained on any of the cards of the six sets placed on the check stakes No parasitization was obtained from the first set in the release area which was exposed from April 26 to 27 In the eecond set parasitization was obtained on seven different cards as follows At 25 feet SE at 50 feet SE S (low) N (high) and N (low) j and at 100 feet E (low) and E (high) On April 26 the wind wa first from the southeast then later a fairly strong wind blew from directly south On April 27 a slight breeze was from the southwest On April 28 there was a fair breeze from the north In the third set parasitization was obtained at 25 feet RE and at 50 feet S (high) In the fourth sd parasitization occurred only at 25 feet S and in the fifth set only at 50 feet S (high) A large number of Trichogramma were still on the center stake on May 1 Parasitizashytion was obtained in the sixth set on five cards all at 50 feet E (high) SE S (high) S (low) and N (low)

On several of the cards all the eggs had been eaten by spidrs ants beetles and other pests although all the stakes had a good band of a sticky material around them just above the surface of the ground No rain fell during this period except for a slight sprinkle on May 2 when the sixth set of cards was being put out

It may be noted that parasitization was obtained as far as 100 feet from the release point within 48 hours after the first release of Irichogramma This agrees very closely with the results of the previous year when parasitization occurred at 25 50 and 75 feet within the first 24 hours after release

These experiments were conducted in April rather than later in the season to minimize interference by parasites already present in the field At the time parasites are being released for control purshyposes the cane is higher and dispersal may vary from that found at these earlier dates

LENGTH OF TOlE P-RASITIZED AND NONPRASITIZED EGG CLUSTERS OF

THE SUGAHCANE BOHEH REMAIN ON PLANTS

To determine the rrlative lenlth of time parasitized and nonshyparasitizrd Pgg clustprs remain on plants and ther(ny the reliabili1iY of counts includillg enwrgecl or hatched ltgg clusters lOS freshly laid borer egg clusters were located and marked on corn and cane at Jeanerette between July 12 and 19 1934 The Illajority of these were on corn These clusters were examined as often as possible until August 14 when other work prevented further obsen~ations One

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

3 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

early mass releases of parasites each year achieve their purpose of increasing this mortality in a manner which results in a measurable decrease in the number of effective borers which survived over the period of liberation and therefore of the final damagl to the crop

Smyth (15) reporting on the technique in the mass production of Trichogramma used to control the cane borer in Peru says

Significant is the fact that as a result of mass colonizations of Trichogramma wasps reared by this technique borer damage was so reduced that the purity and sucrose of the cane (and hence the sugar content) showed a very considerable increase in a large series of fields colonized with parasites over those registered in other fields of the same plantation not so colonized

Mass liberations of Trichogramma have been tried as a control for insects other than the sugarcane borer Peterson (12) in 1930 in experimenting with Trichogramma as a control for the oriental fruit moth (Grapholitha molesta (Busck)) reported

Preliminary field tests in a peach orchard indicate that small liberations of from 300 to 1000 adults per tree are not sufficient to produce parasitism among eggs in adjacent trees

Allen and Warren (1) working with the same insect reported in 1932 at the end of 2 years of investigations that the increased proshyduction of fruit did not justify the added expense The releases were made at the rate of 55000 parasites per acre during each of the two seasons Schread and Garman (14) also experimenting with the release of Trichogramma as a control for the oriental fruit moth reported in 1933 as follows

The average percentage parasitism in 1931 in three orchards where no Trishychoflramma were liberated Wll~ 23 in those orchards where they were liberated it wa 45 percent Observations and field counts indicated that high Trichogramma parasitism was correlated with reduced infestation but the reducshytion was not enough in some cases to be called comtlercial control

List and Davis (11) conducted experiments for 2 years with Trishychogral7lma minutum as a control for the codling moth (CalpOCap8a pomo1~la (L)) and in 1932 made the following statement regarding the results of their experiments

They indicate that during seasons of high natural parasitilm little is accomshyplished by either mass liberations or by colonization of Trichoflramma During seasons of low natural parasitism liberations can be responsible for 0 pronounced parasitism but in no case bas this becn sufficient to show a marked control of the codling moth as indicated by fruit examinations

Schread (13) carried on some cooperative experiments ith A W Morrill and the Associated Sled Growers of Milford to determine the value of releasing Trichogramma for the control of the European corn borer (Pyrausta n-ubilalis (Hbn)) and reported after parasite release at the rate of 10000 20000 and 30000 per acre that

Data accumulated throughout the season wcre not significant from the standshypoint of colonization The averagc parasitism in thc adjacent areas was slightly higher than in thc colonized areas whereas during tbe second brood the results were thc reverse In tbe check plots the average para~iti~m rlurinp the second brood was approximately five times as great as found i~ the colonized areas

Clausrn (2) made thr following statement in 1935 about the liberashytion of Trichogramma as a control for insect pests

In recent years efforts have been made to extend the usefulness of this parasite by rearing the SP( in enormOUR numbers upon grain moth eggs and liberating them in the infestd fields and orchards early in the season This has been tripd on a number of important pests of field crops and orchard trees but the reultB

4 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

thus far have not been conclusive This work is still in the experimental stage and at present it is not recommended to growers as a field prautice

EXPERIMENTS CONDUCTED IN CONNECTION WITH THE GENERAL PROBLEM

In investigating the value of releases of Trichogramma minutum it was found desirable to obtain all information that would be useful in interpreting the data or that would shed additional light on the probshylem The results of these related investigations are given first

OVERWINTERING OF TRICHOGRAMMA

Very little is known about how or where Trichogramma minutum passes the linter months in Louisiana No Diatraea eggs are availshyable from harvest time in the fall until the moths emerge from the overwintered borer larvae in the g~ring a period of from 3 to 5 months Parasitized eggs of Diatraea that have been collected in the fall and kept under the temperatures prevailing at the time have always proshyduced adult~ of Trichogramma within a comparatively short period It seems unlikely that Trichogramma adults hibernate from the faU to the spring as there are days and periods of days during the winter warm enough for adult activity It seems reasonab7Le to assume that mating and egg deposition take place in the field during these warm days as is the case in the laboratory

In an attempt to determine what environments are most conducive to Trichogramma survival over the winter Sitotrola eggs were placed in the field from the lotter part of January through to the middle of May 1933 to determine whether they would be parasitized From 100 to 300 or more eggs were posted on a small piece of cardboard These cardboards were placed in a field in sets of 8 each card being fastened to a small stake and protected from the direct sunlight by a shingle attached to the stake They were put out every 2 weeks and were placed in 4 fields of cane 1 alfalfa field 2 cabbage fields and 1 turnip field 1 wooded swamp and 2 corncribs None of these eggs ever showed signs of parasitization

Searches were made during the winter for eggs of various insects but none of those found had been paratitized by Trichogramma alshythough a live adult of Trichogramma was taken on a mllstardleaf in a small plot at the Houma laboratory on February 5 1934

During the third week in May 1934 16 stakes were so placed that 1 was at the edge of a wood then 1 cnry 100 feet along rows of corn up to 1000 feet then 1 stake (very 200 feet along a row of cane ~n~kshying the last stake 2000 feet from the woods Cardboards ronbunmg bagworm eggs vere placed on these stakes but none werc parasitizEd

It was not knovn what speci(s of eggs might bE available in nature as host material for Triclwgramma during th( winter and (ilrly in the spring As it was v(ry difficult to locate fggs in any nllmb(r that mio-ht be subject to parasitization a few bait traps wer( used (I1ch yer durinO certain periods of the vinter and earlv spring months to obtain a c~llection of the various moths that might be laying eggs that would possibly srrve as hosts A solution of corn sirup and water (1 to 9 plrts) with veast WilS lIs(d as ii bait On iIilrch 20 1933 10 traps were plilcecl50 feet apart along a ditch in iI canefield

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 5

at Houma These traps were removed on April 30 During this period only 185 moths were caught

On February 22 1934 6 traps were placed around an old garden patch that was somewhat overgrown with weeds and brush near an old oak tree at Jeanerette Four other traps were placed between a canefield and a pecan orchard at the same time During the first 15 days 493 moths were caught A new solution was placed in them on March 15 but only 110 moths were taken during the next 15 days The traps near the old garden patch caught many more moths than those alongside the canefield Eggs were obtained from 76 of the moths and adults of Trichogramma minutum were put with some of these eggs Eggs from 22 different individuals were parasitized

Bait traps were again set out at Jeanerette on Janual1J 12 1935 Flve of these traps were placed 100 feet apart along a ditch between two cuts of stubble cane on Albania Plantation The field was surshyrounded by other canefields The other five traps were placed in the woo~s in back of Albania Plantation The first trap was about 230 feet m from the edge of the woods and the others were at 100~foot intervals

Collections of moths were made for 5 days The traps were refilled and collections were made at two later periods The results of the collections are listed in table 1

T~BLE I-Bail-trap collection of moths (all species) at Jeanerette La 1985

Moths collected In-Collection period

Canefield Woods

NUmbtr Number Jan 13-17bullbull _ ______ ___ 171 62 Jan 27-Feb 2_ 9 15 Feb 12-16_ 187 229

TotaL___ 367 306

Out of the 673 moths collected in 1935 129 females deposited eggs in the laboratory Eighty of these females were from the traps in the canefield By exposing these eggs to Trichogramma parasitization was obtained on eggs from 53 different individuals Eggs of 33 of 49 females collected in the woods were also parasitized

Since the moths hftve not been identified the number of species collected which species deposit eggs that are readily parasitized and which deposit eggs not readily parasitized am not yet known Cermiddotmiddot tain species deposited a layer of hairs over the egg cluster and these eggs were seldom parasitized by Trichogramma

It may be noted that there was a considerable difference in the number of moths collected during the three periods of exposure in 1935 It is probable that this difference was due at least in part to variations in temperature The first killing frosts occurred on December 11 and 12 when the minimum temperatures were 26deg and 21 0 F respectively This temperature no doubt killed some of the adult moths present but it did not kill many of the larvae and pupae as a fair number of moths were collected from January 13 to 17 a month after the freeze The second cold spell came between January 22 and 25 when a minimum temperature of 190 was reached This low temperature proha bly

6 TECHJlJCAL BULLETIN 743 U S DEPT OF AGRICULTURE

killed a number of the moths present and very few were collected from January 27 to February 2 lltIoths either were few or else not active as the temperature during this period was lower than during either of the two other collection periods By the time of the third collecshytion however February 12-16 moths were very abundant

Owing to the greater protectbn offered moths it was thought that more eggs might be available for parasitization in the woods during the winter than in the more exposed canefields This may be the case as the moths may go to the woods to deposit their eggs but the moths were apparently as abundant in the canefields as in the woods These collections indicate very clearly that a number of lepidopterous eggs are being laid during the winter and early spring months that could serve as host eggs for Trichogramma minutum

DSPERSAL OF TRICHOGRAMMA lUINUTUl[

Experiments to determine the natural spread of Trichogramma in canefields were carried on in 1933 and 1934 the first year at Houma and the second at Jeanerette

In 1933 2 groups of 56 stakes each were arranged with 8 at 25 feet from the center and 16 each at 50 75 and 100 feet from the center Cards of fresh Sitotroga eggs were placed at ll height of IX feet on all the stakes and additional cards of Sitotroga eggs were placed at a height of 5X feet on 8 of the stakes in each group at the cardinal points of the compass Reference to cards on these 8 stakes will 11ave the additional notation in parentheses as to whether the high or low card is referred to Trichogramma adults were released in the center of 1 group of 8takes The other group which was 740 feet away (center to center) served as a check

As before the cards were protected from the sun by a small shingle Ten sets of cards were used during the period of 13 days on both the release and the check group of stakes Some 75000 Trichogramma adults were released at the center of 1 group of stakes on April 11 just after the first set of cards had bepn placed on the stakes at 8 a m There was a fairly strong wind from the NNW The cards were collected the liext morning and later showed parasitization to have occurred at 25 feet SE j at 50 feet SE SSE and NNW and at 75 feet SSE There Vas no parasitization on the cards from the check group The second set of cards from the release group showed no signs of parasitization but in the check group which was 740 feet directly east of the release group parasitization occurred at 25 feet NW and 100 feet SE from the center of the check group of stakes

On April 13 80000 more Trichogramma were released Cards put out just before this release and left for 48 hours showed parasitization at the following points 25 feet NW W SE and NE 50 feet at WNW N (low) E (low) and NE No parasitization appeared in the check group There was a rainfall of 045 inch between April 13 and 14 Oards for the next 48 hours showed parasitization at 25 feet N Ilnd 50 feet E (low) No parasitization developed in the check group for this set or in any of the later sets

No further parasitization was obtained in the release l0UP until the last set exposed from g a m April 23 to 9 a m April 24 when parasitization occurred at 50 feet E (high) W (high) and WSW The weather during this period was not favorable but thC Cxperiment

EXPERDIEXTIi FOR COXTROL OF SUGARCAXE BORER 7

showed that the parasites spread at least 50 to 75 feet within a few hours after release apparently by drifting with the wind which was smiting

In 1934 2 groups of 40 stakes were arranged with 8 each at 25 50 and 7fi feet from the center and 16 at 100 feet from the center Cards were placed at a height of 1~ feet on all stakes and additional ones as in 1933 were placed at a height of 5~ feet on 8 of them Cards containing fresh bagworm eggs were placed on these stakes and were protected from the sun by small shingles Six sets of cards were used during the period of 9 days The center of the check stakes was 1200 feet west of the point where the releases were made Approximately 40000 Trichogramma adults were released on April 26 and another 40000 were released on April 27 at the center of the test group

No parasitization was obtained on any of the cards of the six sets placed on the check stakes No parasitization was obtained from the first set in the release area which was exposed from April 26 to 27 In the eecond set parasitization was obtained on seven different cards as follows At 25 feet SE at 50 feet SE S (low) N (high) and N (low) j and at 100 feet E (low) and E (high) On April 26 the wind wa first from the southeast then later a fairly strong wind blew from directly south On April 27 a slight breeze was from the southwest On April 28 there was a fair breeze from the north In the third set parasitization was obtained at 25 feet RE and at 50 feet S (high) In the fourth sd parasitization occurred only at 25 feet S and in the fifth set only at 50 feet S (high) A large number of Trichogramma were still on the center stake on May 1 Parasitizashytion was obtained in the sixth set on five cards all at 50 feet E (high) SE S (high) S (low) and N (low)

On several of the cards all the eggs had been eaten by spidrs ants beetles and other pests although all the stakes had a good band of a sticky material around them just above the surface of the ground No rain fell during this period except for a slight sprinkle on May 2 when the sixth set of cards was being put out

It may be noted that parasitization was obtained as far as 100 feet from the release point within 48 hours after the first release of Irichogramma This agrees very closely with the results of the previous year when parasitization occurred at 25 50 and 75 feet within the first 24 hours after release

These experiments were conducted in April rather than later in the season to minimize interference by parasites already present in the field At the time parasites are being released for control purshyposes the cane is higher and dispersal may vary from that found at these earlier dates

LENGTH OF TOlE P-RASITIZED AND NONPRASITIZED EGG CLUSTERS OF

THE SUGAHCANE BOHEH REMAIN ON PLANTS

To determine the rrlative lenlth of time parasitized and nonshyparasitizrd Pgg clustprs remain on plants and ther(ny the reliabili1iY of counts includillg enwrgecl or hatched ltgg clusters lOS freshly laid borer egg clusters were located and marked on corn and cane at Jeanerette between July 12 and 19 1934 The Illajority of these were on corn These clusters were examined as often as possible until August 14 when other work prevented further obsen~ations One

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

4 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

thus far have not been conclusive This work is still in the experimental stage and at present it is not recommended to growers as a field prautice

EXPERIMENTS CONDUCTED IN CONNECTION WITH THE GENERAL PROBLEM

In investigating the value of releases of Trichogramma minutum it was found desirable to obtain all information that would be useful in interpreting the data or that would shed additional light on the probshylem The results of these related investigations are given first

OVERWINTERING OF TRICHOGRAMMA

Very little is known about how or where Trichogramma minutum passes the linter months in Louisiana No Diatraea eggs are availshyable from harvest time in the fall until the moths emerge from the overwintered borer larvae in the g~ring a period of from 3 to 5 months Parasitized eggs of Diatraea that have been collected in the fall and kept under the temperatures prevailing at the time have always proshyduced adult~ of Trichogramma within a comparatively short period It seems unlikely that Trichogramma adults hibernate from the faU to the spring as there are days and periods of days during the winter warm enough for adult activity It seems reasonab7Le to assume that mating and egg deposition take place in the field during these warm days as is the case in the laboratory

In an attempt to determine what environments are most conducive to Trichogramma survival over the winter Sitotrola eggs were placed in the field from the lotter part of January through to the middle of May 1933 to determine whether they would be parasitized From 100 to 300 or more eggs were posted on a small piece of cardboard These cardboards were placed in a field in sets of 8 each card being fastened to a small stake and protected from the direct sunlight by a shingle attached to the stake They were put out every 2 weeks and were placed in 4 fields of cane 1 alfalfa field 2 cabbage fields and 1 turnip field 1 wooded swamp and 2 corncribs None of these eggs ever showed signs of parasitization

Searches were made during the winter for eggs of various insects but none of those found had been paratitized by Trichogramma alshythough a live adult of Trichogramma was taken on a mllstardleaf in a small plot at the Houma laboratory on February 5 1934

During the third week in May 1934 16 stakes were so placed that 1 was at the edge of a wood then 1 cnry 100 feet along rows of corn up to 1000 feet then 1 stake (very 200 feet along a row of cane ~n~kshying the last stake 2000 feet from the woods Cardboards ronbunmg bagworm eggs vere placed on these stakes but none werc parasitizEd

It was not knovn what speci(s of eggs might bE available in nature as host material for Triclwgramma during th( winter and (ilrly in the spring As it was v(ry difficult to locate fggs in any nllmb(r that mio-ht be subject to parasitization a few bait traps wer( used (I1ch yer durinO certain periods of the vinter and earlv spring months to obtain a c~llection of the various moths that might be laying eggs that would possibly srrve as hosts A solution of corn sirup and water (1 to 9 plrts) with veast WilS lIs(d as ii bait On iIilrch 20 1933 10 traps were plilcecl50 feet apart along a ditch in iI canefield

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 5

at Houma These traps were removed on April 30 During this period only 185 moths were caught

On February 22 1934 6 traps were placed around an old garden patch that was somewhat overgrown with weeds and brush near an old oak tree at Jeanerette Four other traps were placed between a canefield and a pecan orchard at the same time During the first 15 days 493 moths were caught A new solution was placed in them on March 15 but only 110 moths were taken during the next 15 days The traps near the old garden patch caught many more moths than those alongside the canefield Eggs were obtained from 76 of the moths and adults of Trichogramma minutum were put with some of these eggs Eggs from 22 different individuals were parasitized

Bait traps were again set out at Jeanerette on Janual1J 12 1935 Flve of these traps were placed 100 feet apart along a ditch between two cuts of stubble cane on Albania Plantation The field was surshyrounded by other canefields The other five traps were placed in the woo~s in back of Albania Plantation The first trap was about 230 feet m from the edge of the woods and the others were at 100~foot intervals

Collections of moths were made for 5 days The traps were refilled and collections were made at two later periods The results of the collections are listed in table 1

T~BLE I-Bail-trap collection of moths (all species) at Jeanerette La 1985

Moths collected In-Collection period

Canefield Woods

NUmbtr Number Jan 13-17bullbull _ ______ ___ 171 62 Jan 27-Feb 2_ 9 15 Feb 12-16_ 187 229

TotaL___ 367 306

Out of the 673 moths collected in 1935 129 females deposited eggs in the laboratory Eighty of these females were from the traps in the canefield By exposing these eggs to Trichogramma parasitization was obtained on eggs from 53 different individuals Eggs of 33 of 49 females collected in the woods were also parasitized

Since the moths hftve not been identified the number of species collected which species deposit eggs that are readily parasitized and which deposit eggs not readily parasitized am not yet known Cermiddotmiddot tain species deposited a layer of hairs over the egg cluster and these eggs were seldom parasitized by Trichogramma

It may be noted that there was a considerable difference in the number of moths collected during the three periods of exposure in 1935 It is probable that this difference was due at least in part to variations in temperature The first killing frosts occurred on December 11 and 12 when the minimum temperatures were 26deg and 21 0 F respectively This temperature no doubt killed some of the adult moths present but it did not kill many of the larvae and pupae as a fair number of moths were collected from January 13 to 17 a month after the freeze The second cold spell came between January 22 and 25 when a minimum temperature of 190 was reached This low temperature proha bly

6 TECHJlJCAL BULLETIN 743 U S DEPT OF AGRICULTURE

killed a number of the moths present and very few were collected from January 27 to February 2 lltIoths either were few or else not active as the temperature during this period was lower than during either of the two other collection periods By the time of the third collecshytion however February 12-16 moths were very abundant

Owing to the greater protectbn offered moths it was thought that more eggs might be available for parasitization in the woods during the winter than in the more exposed canefields This may be the case as the moths may go to the woods to deposit their eggs but the moths were apparently as abundant in the canefields as in the woods These collections indicate very clearly that a number of lepidopterous eggs are being laid during the winter and early spring months that could serve as host eggs for Trichogramma minutum

DSPERSAL OF TRICHOGRAMMA lUINUTUl[

Experiments to determine the natural spread of Trichogramma in canefields were carried on in 1933 and 1934 the first year at Houma and the second at Jeanerette

In 1933 2 groups of 56 stakes each were arranged with 8 at 25 feet from the center and 16 each at 50 75 and 100 feet from the center Cards of fresh Sitotroga eggs were placed at ll height of IX feet on all the stakes and additional cards of Sitotroga eggs were placed at a height of 5X feet on 8 of the stakes in each group at the cardinal points of the compass Reference to cards on these 8 stakes will 11ave the additional notation in parentheses as to whether the high or low card is referred to Trichogramma adults were released in the center of 1 group of 8takes The other group which was 740 feet away (center to center) served as a check

As before the cards were protected from the sun by a small shingle Ten sets of cards were used during the period of 13 days on both the release and the check group of stakes Some 75000 Trichogramma adults were released at the center of 1 group of stakes on April 11 just after the first set of cards had bepn placed on the stakes at 8 a m There was a fairly strong wind from the NNW The cards were collected the liext morning and later showed parasitization to have occurred at 25 feet SE j at 50 feet SE SSE and NNW and at 75 feet SSE There Vas no parasitization on the cards from the check group The second set of cards from the release group showed no signs of parasitization but in the check group which was 740 feet directly east of the release group parasitization occurred at 25 feet NW and 100 feet SE from the center of the check group of stakes

On April 13 80000 more Trichogramma were released Cards put out just before this release and left for 48 hours showed parasitization at the following points 25 feet NW W SE and NE 50 feet at WNW N (low) E (low) and NE No parasitization appeared in the check group There was a rainfall of 045 inch between April 13 and 14 Oards for the next 48 hours showed parasitization at 25 feet N Ilnd 50 feet E (low) No parasitization developed in the check group for this set or in any of the later sets

No further parasitization was obtained in the release l0UP until the last set exposed from g a m April 23 to 9 a m April 24 when parasitization occurred at 50 feet E (high) W (high) and WSW The weather during this period was not favorable but thC Cxperiment

EXPERDIEXTIi FOR COXTROL OF SUGARCAXE BORER 7

showed that the parasites spread at least 50 to 75 feet within a few hours after release apparently by drifting with the wind which was smiting

In 1934 2 groups of 40 stakes were arranged with 8 each at 25 50 and 7fi feet from the center and 16 at 100 feet from the center Cards were placed at a height of 1~ feet on all stakes and additional ones as in 1933 were placed at a height of 5~ feet on 8 of them Cards containing fresh bagworm eggs were placed on these stakes and were protected from the sun by small shingles Six sets of cards were used during the period of 9 days The center of the check stakes was 1200 feet west of the point where the releases were made Approximately 40000 Trichogramma adults were released on April 26 and another 40000 were released on April 27 at the center of the test group

No parasitization was obtained on any of the cards of the six sets placed on the check stakes No parasitization was obtained from the first set in the release area which was exposed from April 26 to 27 In the eecond set parasitization was obtained on seven different cards as follows At 25 feet SE at 50 feet SE S (low) N (high) and N (low) j and at 100 feet E (low) and E (high) On April 26 the wind wa first from the southeast then later a fairly strong wind blew from directly south On April 27 a slight breeze was from the southwest On April 28 there was a fair breeze from the north In the third set parasitization was obtained at 25 feet RE and at 50 feet S (high) In the fourth sd parasitization occurred only at 25 feet S and in the fifth set only at 50 feet S (high) A large number of Trichogramma were still on the center stake on May 1 Parasitizashytion was obtained in the sixth set on five cards all at 50 feet E (high) SE S (high) S (low) and N (low)

On several of the cards all the eggs had been eaten by spidrs ants beetles and other pests although all the stakes had a good band of a sticky material around them just above the surface of the ground No rain fell during this period except for a slight sprinkle on May 2 when the sixth set of cards was being put out

It may be noted that parasitization was obtained as far as 100 feet from the release point within 48 hours after the first release of Irichogramma This agrees very closely with the results of the previous year when parasitization occurred at 25 50 and 75 feet within the first 24 hours after release

These experiments were conducted in April rather than later in the season to minimize interference by parasites already present in the field At the time parasites are being released for control purshyposes the cane is higher and dispersal may vary from that found at these earlier dates

LENGTH OF TOlE P-RASITIZED AND NONPRASITIZED EGG CLUSTERS OF

THE SUGAHCANE BOHEH REMAIN ON PLANTS

To determine the rrlative lenlth of time parasitized and nonshyparasitizrd Pgg clustprs remain on plants and ther(ny the reliabili1iY of counts includillg enwrgecl or hatched ltgg clusters lOS freshly laid borer egg clusters were located and marked on corn and cane at Jeanerette between July 12 and 19 1934 The Illajority of these were on corn These clusters were examined as often as possible until August 14 when other work prevented further obsen~ations One

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 5

at Houma These traps were removed on April 30 During this period only 185 moths were caught

On February 22 1934 6 traps were placed around an old garden patch that was somewhat overgrown with weeds and brush near an old oak tree at Jeanerette Four other traps were placed between a canefield and a pecan orchard at the same time During the first 15 days 493 moths were caught A new solution was placed in them on March 15 but only 110 moths were taken during the next 15 days The traps near the old garden patch caught many more moths than those alongside the canefield Eggs were obtained from 76 of the moths and adults of Trichogramma minutum were put with some of these eggs Eggs from 22 different individuals were parasitized

Bait traps were again set out at Jeanerette on Janual1J 12 1935 Flve of these traps were placed 100 feet apart along a ditch between two cuts of stubble cane on Albania Plantation The field was surshyrounded by other canefields The other five traps were placed in the woo~s in back of Albania Plantation The first trap was about 230 feet m from the edge of the woods and the others were at 100~foot intervals

Collections of moths were made for 5 days The traps were refilled and collections were made at two later periods The results of the collections are listed in table 1

T~BLE I-Bail-trap collection of moths (all species) at Jeanerette La 1985

Moths collected In-Collection period

Canefield Woods

NUmbtr Number Jan 13-17bullbull _ ______ ___ 171 62 Jan 27-Feb 2_ 9 15 Feb 12-16_ 187 229

TotaL___ 367 306

Out of the 673 moths collected in 1935 129 females deposited eggs in the laboratory Eighty of these females were from the traps in the canefield By exposing these eggs to Trichogramma parasitization was obtained on eggs from 53 different individuals Eggs of 33 of 49 females collected in the woods were also parasitized

Since the moths hftve not been identified the number of species collected which species deposit eggs that are readily parasitized and which deposit eggs not readily parasitized am not yet known Cermiddotmiddot tain species deposited a layer of hairs over the egg cluster and these eggs were seldom parasitized by Trichogramma

It may be noted that there was a considerable difference in the number of moths collected during the three periods of exposure in 1935 It is probable that this difference was due at least in part to variations in temperature The first killing frosts occurred on December 11 and 12 when the minimum temperatures were 26deg and 21 0 F respectively This temperature no doubt killed some of the adult moths present but it did not kill many of the larvae and pupae as a fair number of moths were collected from January 13 to 17 a month after the freeze The second cold spell came between January 22 and 25 when a minimum temperature of 190 was reached This low temperature proha bly

6 TECHJlJCAL BULLETIN 743 U S DEPT OF AGRICULTURE

killed a number of the moths present and very few were collected from January 27 to February 2 lltIoths either were few or else not active as the temperature during this period was lower than during either of the two other collection periods By the time of the third collecshytion however February 12-16 moths were very abundant

Owing to the greater protectbn offered moths it was thought that more eggs might be available for parasitization in the woods during the winter than in the more exposed canefields This may be the case as the moths may go to the woods to deposit their eggs but the moths were apparently as abundant in the canefields as in the woods These collections indicate very clearly that a number of lepidopterous eggs are being laid during the winter and early spring months that could serve as host eggs for Trichogramma minutum

DSPERSAL OF TRICHOGRAMMA lUINUTUl[

Experiments to determine the natural spread of Trichogramma in canefields were carried on in 1933 and 1934 the first year at Houma and the second at Jeanerette

In 1933 2 groups of 56 stakes each were arranged with 8 at 25 feet from the center and 16 each at 50 75 and 100 feet from the center Cards of fresh Sitotroga eggs were placed at ll height of IX feet on all the stakes and additional cards of Sitotroga eggs were placed at a height of 5X feet on 8 of the stakes in each group at the cardinal points of the compass Reference to cards on these 8 stakes will 11ave the additional notation in parentheses as to whether the high or low card is referred to Trichogramma adults were released in the center of 1 group of 8takes The other group which was 740 feet away (center to center) served as a check

As before the cards were protected from the sun by a small shingle Ten sets of cards were used during the period of 13 days on both the release and the check group of stakes Some 75000 Trichogramma adults were released at the center of 1 group of stakes on April 11 just after the first set of cards had bepn placed on the stakes at 8 a m There was a fairly strong wind from the NNW The cards were collected the liext morning and later showed parasitization to have occurred at 25 feet SE j at 50 feet SE SSE and NNW and at 75 feet SSE There Vas no parasitization on the cards from the check group The second set of cards from the release group showed no signs of parasitization but in the check group which was 740 feet directly east of the release group parasitization occurred at 25 feet NW and 100 feet SE from the center of the check group of stakes

On April 13 80000 more Trichogramma were released Cards put out just before this release and left for 48 hours showed parasitization at the following points 25 feet NW W SE and NE 50 feet at WNW N (low) E (low) and NE No parasitization appeared in the check group There was a rainfall of 045 inch between April 13 and 14 Oards for the next 48 hours showed parasitization at 25 feet N Ilnd 50 feet E (low) No parasitization developed in the check group for this set or in any of the later sets

No further parasitization was obtained in the release l0UP until the last set exposed from g a m April 23 to 9 a m April 24 when parasitization occurred at 50 feet E (high) W (high) and WSW The weather during this period was not favorable but thC Cxperiment

EXPERDIEXTIi FOR COXTROL OF SUGARCAXE BORER 7

showed that the parasites spread at least 50 to 75 feet within a few hours after release apparently by drifting with the wind which was smiting

In 1934 2 groups of 40 stakes were arranged with 8 each at 25 50 and 7fi feet from the center and 16 at 100 feet from the center Cards were placed at a height of 1~ feet on all stakes and additional ones as in 1933 were placed at a height of 5~ feet on 8 of them Cards containing fresh bagworm eggs were placed on these stakes and were protected from the sun by small shingles Six sets of cards were used during the period of 9 days The center of the check stakes was 1200 feet west of the point where the releases were made Approximately 40000 Trichogramma adults were released on April 26 and another 40000 were released on April 27 at the center of the test group

No parasitization was obtained on any of the cards of the six sets placed on the check stakes No parasitization was obtained from the first set in the release area which was exposed from April 26 to 27 In the eecond set parasitization was obtained on seven different cards as follows At 25 feet SE at 50 feet SE S (low) N (high) and N (low) j and at 100 feet E (low) and E (high) On April 26 the wind wa first from the southeast then later a fairly strong wind blew from directly south On April 27 a slight breeze was from the southwest On April 28 there was a fair breeze from the north In the third set parasitization was obtained at 25 feet RE and at 50 feet S (high) In the fourth sd parasitization occurred only at 25 feet S and in the fifth set only at 50 feet S (high) A large number of Trichogramma were still on the center stake on May 1 Parasitizashytion was obtained in the sixth set on five cards all at 50 feet E (high) SE S (high) S (low) and N (low)

On several of the cards all the eggs had been eaten by spidrs ants beetles and other pests although all the stakes had a good band of a sticky material around them just above the surface of the ground No rain fell during this period except for a slight sprinkle on May 2 when the sixth set of cards was being put out

It may be noted that parasitization was obtained as far as 100 feet from the release point within 48 hours after the first release of Irichogramma This agrees very closely with the results of the previous year when parasitization occurred at 25 50 and 75 feet within the first 24 hours after release

These experiments were conducted in April rather than later in the season to minimize interference by parasites already present in the field At the time parasites are being released for control purshyposes the cane is higher and dispersal may vary from that found at these earlier dates

LENGTH OF TOlE P-RASITIZED AND NONPRASITIZED EGG CLUSTERS OF

THE SUGAHCANE BOHEH REMAIN ON PLANTS

To determine the rrlative lenlth of time parasitized and nonshyparasitizrd Pgg clustprs remain on plants and ther(ny the reliabili1iY of counts includillg enwrgecl or hatched ltgg clusters lOS freshly laid borer egg clusters were located and marked on corn and cane at Jeanerette between July 12 and 19 1934 The Illajority of these were on corn These clusters were examined as often as possible until August 14 when other work prevented further obsen~ations One

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

6 TECHJlJCAL BULLETIN 743 U S DEPT OF AGRICULTURE

killed a number of the moths present and very few were collected from January 27 to February 2 lltIoths either were few or else not active as the temperature during this period was lower than during either of the two other collection periods By the time of the third collecshytion however February 12-16 moths were very abundant

Owing to the greater protectbn offered moths it was thought that more eggs might be available for parasitization in the woods during the winter than in the more exposed canefields This may be the case as the moths may go to the woods to deposit their eggs but the moths were apparently as abundant in the canefields as in the woods These collections indicate very clearly that a number of lepidopterous eggs are being laid during the winter and early spring months that could serve as host eggs for Trichogramma minutum

DSPERSAL OF TRICHOGRAMMA lUINUTUl[

Experiments to determine the natural spread of Trichogramma in canefields were carried on in 1933 and 1934 the first year at Houma and the second at Jeanerette

In 1933 2 groups of 56 stakes each were arranged with 8 at 25 feet from the center and 16 each at 50 75 and 100 feet from the center Cards of fresh Sitotroga eggs were placed at ll height of IX feet on all the stakes and additional cards of Sitotroga eggs were placed at a height of 5X feet on 8 of the stakes in each group at the cardinal points of the compass Reference to cards on these 8 stakes will 11ave the additional notation in parentheses as to whether the high or low card is referred to Trichogramma adults were released in the center of 1 group of 8takes The other group which was 740 feet away (center to center) served as a check

As before the cards were protected from the sun by a small shingle Ten sets of cards were used during the period of 13 days on both the release and the check group of stakes Some 75000 Trichogramma adults were released at the center of 1 group of stakes on April 11 just after the first set of cards had bepn placed on the stakes at 8 a m There was a fairly strong wind from the NNW The cards were collected the liext morning and later showed parasitization to have occurred at 25 feet SE j at 50 feet SE SSE and NNW and at 75 feet SSE There Vas no parasitization on the cards from the check group The second set of cards from the release group showed no signs of parasitization but in the check group which was 740 feet directly east of the release group parasitization occurred at 25 feet NW and 100 feet SE from the center of the check group of stakes

On April 13 80000 more Trichogramma were released Cards put out just before this release and left for 48 hours showed parasitization at the following points 25 feet NW W SE and NE 50 feet at WNW N (low) E (low) and NE No parasitization appeared in the check group There was a rainfall of 045 inch between April 13 and 14 Oards for the next 48 hours showed parasitization at 25 feet N Ilnd 50 feet E (low) No parasitization developed in the check group for this set or in any of the later sets

No further parasitization was obtained in the release l0UP until the last set exposed from g a m April 23 to 9 a m April 24 when parasitization occurred at 50 feet E (high) W (high) and WSW The weather during this period was not favorable but thC Cxperiment

EXPERDIEXTIi FOR COXTROL OF SUGARCAXE BORER 7

showed that the parasites spread at least 50 to 75 feet within a few hours after release apparently by drifting with the wind which was smiting

In 1934 2 groups of 40 stakes were arranged with 8 each at 25 50 and 7fi feet from the center and 16 at 100 feet from the center Cards were placed at a height of 1~ feet on all stakes and additional ones as in 1933 were placed at a height of 5~ feet on 8 of them Cards containing fresh bagworm eggs were placed on these stakes and were protected from the sun by small shingles Six sets of cards were used during the period of 9 days The center of the check stakes was 1200 feet west of the point where the releases were made Approximately 40000 Trichogramma adults were released on April 26 and another 40000 were released on April 27 at the center of the test group

No parasitization was obtained on any of the cards of the six sets placed on the check stakes No parasitization was obtained from the first set in the release area which was exposed from April 26 to 27 In the eecond set parasitization was obtained on seven different cards as follows At 25 feet SE at 50 feet SE S (low) N (high) and N (low) j and at 100 feet E (low) and E (high) On April 26 the wind wa first from the southeast then later a fairly strong wind blew from directly south On April 27 a slight breeze was from the southwest On April 28 there was a fair breeze from the north In the third set parasitization was obtained at 25 feet RE and at 50 feet S (high) In the fourth sd parasitization occurred only at 25 feet S and in the fifth set only at 50 feet S (high) A large number of Trichogramma were still on the center stake on May 1 Parasitizashytion was obtained in the sixth set on five cards all at 50 feet E (high) SE S (high) S (low) and N (low)

On several of the cards all the eggs had been eaten by spidrs ants beetles and other pests although all the stakes had a good band of a sticky material around them just above the surface of the ground No rain fell during this period except for a slight sprinkle on May 2 when the sixth set of cards was being put out

It may be noted that parasitization was obtained as far as 100 feet from the release point within 48 hours after the first release of Irichogramma This agrees very closely with the results of the previous year when parasitization occurred at 25 50 and 75 feet within the first 24 hours after release

These experiments were conducted in April rather than later in the season to minimize interference by parasites already present in the field At the time parasites are being released for control purshyposes the cane is higher and dispersal may vary from that found at these earlier dates

LENGTH OF TOlE P-RASITIZED AND NONPRASITIZED EGG CLUSTERS OF

THE SUGAHCANE BOHEH REMAIN ON PLANTS

To determine the rrlative lenlth of time parasitized and nonshyparasitizrd Pgg clustprs remain on plants and ther(ny the reliabili1iY of counts includillg enwrgecl or hatched ltgg clusters lOS freshly laid borer egg clusters were located and marked on corn and cane at Jeanerette between July 12 and 19 1934 The Illajority of these were on corn These clusters were examined as often as possible until August 14 when other work prevented further obsen~ations One

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

EXPERDIEXTIi FOR COXTROL OF SUGARCAXE BORER 7

showed that the parasites spread at least 50 to 75 feet within a few hours after release apparently by drifting with the wind which was smiting

In 1934 2 groups of 40 stakes were arranged with 8 each at 25 50 and 7fi feet from the center and 16 at 100 feet from the center Cards were placed at a height of 1~ feet on all stakes and additional ones as in 1933 were placed at a height of 5~ feet on 8 of them Cards containing fresh bagworm eggs were placed on these stakes and were protected from the sun by small shingles Six sets of cards were used during the period of 9 days The center of the check stakes was 1200 feet west of the point where the releases were made Approximately 40000 Trichogramma adults were released on April 26 and another 40000 were released on April 27 at the center of the test group

No parasitization was obtained on any of the cards of the six sets placed on the check stakes No parasitization was obtained from the first set in the release area which was exposed from April 26 to 27 In the eecond set parasitization was obtained on seven different cards as follows At 25 feet SE at 50 feet SE S (low) N (high) and N (low) j and at 100 feet E (low) and E (high) On April 26 the wind wa first from the southeast then later a fairly strong wind blew from directly south On April 27 a slight breeze was from the southwest On April 28 there was a fair breeze from the north In the third set parasitization was obtained at 25 feet RE and at 50 feet S (high) In the fourth sd parasitization occurred only at 25 feet S and in the fifth set only at 50 feet S (high) A large number of Trichogramma were still on the center stake on May 1 Parasitizashytion was obtained in the sixth set on five cards all at 50 feet E (high) SE S (high) S (low) and N (low)

On several of the cards all the eggs had been eaten by spidrs ants beetles and other pests although all the stakes had a good band of a sticky material around them just above the surface of the ground No rain fell during this period except for a slight sprinkle on May 2 when the sixth set of cards was being put out

It may be noted that parasitization was obtained as far as 100 feet from the release point within 48 hours after the first release of Irichogramma This agrees very closely with the results of the previous year when parasitization occurred at 25 50 and 75 feet within the first 24 hours after release

These experiments were conducted in April rather than later in the season to minimize interference by parasites already present in the field At the time parasites are being released for control purshyposes the cane is higher and dispersal may vary from that found at these earlier dates

LENGTH OF TOlE P-RASITIZED AND NONPRASITIZED EGG CLUSTERS OF

THE SUGAHCANE BOHEH REMAIN ON PLANTS

To determine the rrlative lenlth of time parasitized and nonshyparasitizrd Pgg clustprs remain on plants and ther(ny the reliabili1iY of counts includillg enwrgecl or hatched ltgg clusters lOS freshly laid borer egg clusters were located and marked on corn and cane at Jeanerette between July 12 and 19 1934 The Illajority of these were on corn These clusters were examined as often as possible until August 14 when other work prevented further obsen~ations One

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

8 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

hundred and sixty-four clusters or part clusters that were not parasitized remained on the leaves an average of 234 days Fiftyshyseven clusters or part clusters that were parasitized remained on the leaves an average of 214 days It appears from these observations that there is little difference between the length of adherence to leaves of parasitized and nonparasitized egg clusters If the observations had not been interrupted results at variance from these might have been obtained

RELATION OF ACTUALLY BORED JOINTS TO JOINTS SHmVING BORER INJURY EXTERNALLY

Investigators in this and in other countries llaye diffNed on the best methods for determining borer injury to sugarcane Some have usrd only the percentage of stalks bored and have not made counts of joints bored Since the reliability of joint counts as a measure of borer injury was unknown investigations were conducted to detershymine their dependability

During the 3 harvrst seasons of 1933-35 200 stalks per plot were usually examined to determine the nUIber of borrd stalks and bored joints and thereby the re1atiye damage in colonized buffer and check plots Of these 200 stalks examined 50 stalks per plot were split and examined for internal borer injury in each experiment except in those ~n Jeanerettr in 1935 In all 6235 stalks were split open and a record was made of the total joints bored and of those that showed this damage externally Of the 6235 stalks split 556i werr bored and the record of the joints bored externally and internally is shown in table 2 It was though that in some eases a borer might entN a stalk and bore through scyeral joints and the stalk might show externally only 1 or 2 bored joints It will be seen from table 2 that of all the stalks examined only 1 showed a count of 5 joints morr bored internally than showed externally There were 2 stalks shOing 4 morc bored internally than showed externally and the usual limit was not more than 3 and this in a very small proportion

TABLE 2-Su7Ilber of joints of SllgarC07ie classified with re~pect 10 both joillis bored externally and joints bored iTltemally by the sugarcane borer LouisiaTla 1933-85

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

EXPERIMENTS FOR CONTROL OF SUGARCANE ~ORER 9

To ascertain the degree of association between externally and intershynally bored joints the coefficient of correlation was obtained and found to he 097 with a probable error of 00059 This correlation was based on the total of all stalks examined no consideration being given to variation due to variety and to year of crop

With the knowledge of this high degree of correlation considerable time can be saved in making infestation counts by substituting external for internal examinations and it becomes unnecessary to destroy a large number of stalks just before harvesting

The data obtained by splitting the stalks have been arranged in table 3 to indicate the number of joints showing boring externally the total number of joints bored intcrnaJly the number of stalks bored the number of joints bored internally per stalk and the ratio of the number of joints bored internally to the number of joints showing boring externally

TABLE 3-Ratio of joints of sugarcane showing externally and iTlternally the boring of the Iugarcane borer Louisiana 1933-85

Ratio or the number or

Total joints Joints bored joints bored StalksJoints showing boring externally (number) bored inmiddot Internally Internally to boredternally per stalk the number or joints bored externally

Number Number Number14_______________bull __ bullbullbullbull ___ bullbullbull ___ bullbullbull _bullbullbullbullbullbull__ bullbullbullbull_ __ bull iO 5 14000 1000013__ bull _______ bull ______________ bull ___ _ _____bull __ bullbull_bullbullbull _ 54 4 13500 1038512 _________ bull __ bull ______bullbullbullbull __bull ____bullbull___ _bullbull _bullbullbullbullbullbullbull ____ _ 110 9 12222 10185 11 ______bull ___ bull ______ __bullbull___ bullbullbullbullbullbull _ __ bull _ _______ __ 206 18 11444 10404 10____ bullbullbull ___ bullbull _____ bullbullbull ___ bullbullbullbull __ bullbullbullbullbullbullbull __ bullbullbull _bullbullbullbull 486 47 10340 10340 9_ bullbull __bullbull____ _bullbullbullbullbullbull _ _bullbullbullbullbullbullbullbullbull _bullbullbullbullbullbullbullbull _bullbull _bull _ ~88 96 92W 10278 8 bullbull _bullbullbullbull_bullbull___ bullbullbullbullbullbullbullbullbullbullbullbullbullbull __ bullbullbullbullbull__ bullbullbullbull ____ bullbull 1279 152 8414 1 0518 7bullbullbullbullbullbullbullbullbull_bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __bullbull____ ____bullbullbull _bullbullbull_ 1915 262 7309 10441 6_bullbullbullbullbullbull_bullbullbullbullbull _bullbullbullbullbull_bullbull ___ bullbull__ bull__ __ bull ___ 2 662 422 6308 IOmiddot~13 5_bullbullbullbullbull ____ ___ __ _bullbull__bullbull bull __ bullbullbull 3340 627 5327 106M 4_bullbullbullbull __ bullbull __ bullbull_bullbullbull _bullbull _____ bullbull __ ___bullbullbullbullbullbull_ 3777 874 4822 10805 3 bullbull _bull __ bull_ _bull _bull_bullbullbullbull__ bull__ _ _ ___ bullbull bullbull_ 3 680 1097 3 3M 11183

1111 2285 11W 843 11400

1-------1-------1middot-------1------shyi===== 2 =~ 1140

Total _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull__ ____bullbull__bullbull__ 21967 6567 _bullbullbull _bullbullbullbullbullbullbullbull __ bull ___ bullbullbullbullbullbullbull

RELATION OF RATE OF PARASITIZATION TO HOST DENSITY

In the early parts of the three seasons the parasitization ranged from 0 to 100 percent while toward the latter part of the season it was always fairly high

The eggs collected from July 18 to September 28 1933 have been grouped in table 4 according to the number of eggs found per unit hour of search In comparing the percentage of parasitization with the average number of eggs found per hour it will be noted that parashysitization rises very rapidly until some 400 eggs per hour are found After that there is a slight rise until when from 800 to 2800 (ggs are found per hour there is very little difference in the perc(ntage of parnsi tiza tion

To ascertain whether there was l possible correlation between the percentage of parasitization and the host density a correlation table was made in which all eggs collected on an hourly basis between JUly 2 and September 28 in the 3 years were plotted The class groups for the eggs were 1-50 51-100 etc up to 4701-4750 and

2-15990-41-2

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

----

10 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

included 522 separate hourly collections The class groups for thl~ percentage of parasitization ware O1-50 6-10 11-15 etc The coefficient of correlation was found to be 059 with a probable error of plusmnO019 This shows that there is a decided correlation between percentage of parasitization and host density

TBLE 4-Rae of parasitization of sugarcane borer egps by Trichogramma minutum as related to the number found pc init hour of search in Louisiana 1938

Total Total ~ggs Averall) A vcrnge Eggs found per hour July 18 to Sept 28 hour Total eggs parasitized parasitli-a (or eggs per(number) units tlon unit hour

Numbtr NuTlfitr Numbtr Pactnt Numbtr 1 to 50bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 23 581 18 31 253 51 to 10(L 19 1381 371 273 127 lfil to 150 14 1873 585 312 1338

bull Vii to 200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 9 1518 IOSI 712 168 T 201 to 400bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 22 6352 4 289 615 288 T 401 to 600bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 12 6050 5181 856 5042 601 to 800bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 15 10263 8619 840 M42 801 to 1000bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 6 5240 4806 91 7 8133 1001 to 1200bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 2 2140 2065 005 10700 1201 to 1400bullbullbull bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 4 5138 4561 888 12845 1401 to 1800 4 58112 5391 915 14730 1601 to 1800 1 1795 1amp13 915 17950 1801 to 2000 1 1990 1667 838 I9901t 2001 to 2200 3 6328 6042 956 2 107 6 2201 to 2400 1 2260 2061 912 12600 2401 to 2800 o 2601 to 2800 1

In collecting borer egg clusters in 1934 and 1935 each unit of colshylecting was divided into 10-minute periods and a record was kept both of the number of clusters ana the percentage of parasitization of the eggs in the various IO-minute collecting periods To determine the reliability of the egg collections made in connection with the TrchofJTamma experiments a statistical analysis was made of the 1934 data from the Houma area with the assistance of George Arceshyneaux agronomist of the Bureau of Plant Industry This study showed that data on parasitism obtained by egg collections prior to August were of doubtful reliability and that only the data obtained during August and September were dependable During the spring and epoundiy summer months the primary purpose in making egg colshylections was to determine the prevalence of borer e~gs so as to time parasite releases properly Data on egg collections In 1934 are given in table 5

TABLE 5-Average numbers of egg clllsters of the sugarcane borer collected per lO-minute period at different dates during 1984 at Houma La

~VCralP (orEgg clusshyI()minute clusters perOu11eetlon dates tenperiods l()mlnut8collected period

Number Numbtr Number Apr 15-30 108 40 037 May 10-25 72 6 08 June 1-15 lil 81 53 June 16-30 50 86 17 Jnly 1-15 00 244 27 July 16-31 lOS 293 21 Aug 1-31 198 920 4 ft Sept 1-30___1_80_1-___ 2310___ 128_

TfltaJ and averagel 959 39M I 415

11 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

EXPERIMENTS WITH TRICHOGRAMMA MINUTUM IN THE CONTROL OF TilE SUGARCANE BORER

During the seasons of 1933 1934 and 1935 experirnents were conshyducted by the authors in Louisiana to determine the effiacy of mass releases of the egg parasite Trichogramma minutum for the control of the sugarcane borer in sugarcane A preliminary report (10) covering results of these experiments has ftlready been published

Nine experiments wen carried on in cooperation with the Louisian3 Agricultural Experiment Station in 1934 and 1935 In 1934 two of these were located on Raceland Plantation Raceland La and in 1935 four were conducted on Reserve Plantation Reserve La and three on Shadyside Plantation at Centerville La Parasite releases were made jointly in these experiments the parasites being supplied by either the State or Bureau representatives or in some cases by both The Bureau representatives made egg collections infestation counts and small-mill analyses of the cane separate from those made by the State The harvest records and factory analyses of these experiments were usually obtained jointly A Bureau representative was present during the harvesting for all experiments These cooperative experishyments are designated in 1111 the tables by the letter c preceding the experiment number

SELECTION OF EXPERIMENTAL FIELDS

In 1933 Trichogramma adults were released on 1 i plots of sugarcane and 15 comparable plots were used as checks with 10 intervening plots serving as buffers These plots ranged in size from 273 to 2600 acres In selecting the plots care was taken to sec that the stand and soil of the colonized plot and corresponding check were as nearly similar as possible Practically all the experiments were conducted with varieties of sugarcane most subject to heavy borer injury and were located in the vicinity of Houma Franklin or Plaquemine where the injury was usually above the average

Ten experiments were carried on in the Jeanerette area and 10 in the Houma area in 1934 and in 1935 11 experiments were completed in the Houma area Imd 9 in the Jeanerette area Each experiment covered an area on which parasites were colonized and an untreated check area of approximately the same size with an intervening area usually larger called the buffer Smaller plots were used than in 1933 In 1934 the colonized areas ranged from 253 to 784 acres the buffer arells from 314 to 957 acres and the check areas from 234 to 718 acres In 1935 the colonized areas ranged from 109 to 687 acres the buffer areas from 231 to 864 acres and the check areas from 109 to 497 acres

Still greater care was taken during these years in selecting the areas as all experimental plots were checked for uniformity of soil type by A M ONeal associate soil technologist of the Bureau ~f Plant Industry ilnd were tlpproved by him as comparable for experishymental purposes All experimental areas were also checked with pluntation managers scientific advisors for the plantations and overshyseers for similarity of past treatments and equality of post yields In 1935 as a further check on the similarity of the colonized buffer and check plots of each experiment measurements of gaps in the rows were made All gaps of over 18 inches were recorded Usually

12 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

100 f~et of row in 20 scattered locations in each of the colonized buffer and check plots or 6000 feet for each experiment was examshyined and measured for gaps The gaps were recorded in groups of 6 inches above the 18-inch gap Those gaps measuring between 18 and 24 inches would fall in group 1 with an average of 175 feet those between 24 and 30 inches in group 2 with an average of 225 feet and so on From the total of the gap measurements and the

total number of feet exshyNORTH amined the percentage

of gaps was obtained Gap counts were made

CO81 FIRSTshySTUBBLE CANE CO281 FIRST-STUBBLE CANE SOYBEANS in all canefields that

were being considered for use in the Trichoshygramma experiments

Nearly twice as manyROAD fields as would be used

t 1521 ACRES for the experiments I were tentatively selectshyI

I ed each26 P 1155 ACRES early season I During subsequent

CO281 FIRSTshy~

examinations somet STUBBLE CANE I 1814 ACRES fields had to be elimishy

I nated becalise of an I

uneven stand others because of exceptional-

I SOYBEANS ly light infestations of

1864 ACRES

I I I 2395 ACRES borers and others ~ I because gap measureshy

ments indicated thatt I 2391 the stand was not unishyACRES I form The study of a I

26 C large number of fields I and the checking of theI 2366 ACRES I progress of cane growth ~ and borer infestation

co 281 FIRST-STUBBLE CANE SOYBEANS from the first of the season to the time when they were ready

FIGURE I-Typical lay-out of a Trichogramma ex- for parasites gave a periment in a field of Co 281 first-stubble cane better opportunity to as conducted during 1934 and 1935 at New Hope select fields that were Plantation Lafourche Parish La 26P represents comparable for use in the two cuts on which the parasites were released in exp~riment 26 26B the corresponding buffer the experiments than area 26C the ~heck could be had by waitshy

ing un til moths of the second generation were laying eggs and selecting the plots then or even later Fields were selected where the borers were usually most numerous

The immediate enviionments of the fields used were also considered care being taken to see that where possible the colonized and check areas were bordered by a similar kind of crop A diagram showing the plan of an experiment is given in figure 1 This is typical of the experimental fields used in 1934 and 1935 In some cases however

13 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

the colonized plot or the check plot cOJisisted of only one cut instead of two The buffer ranged from two to five cuts depending on the size of the field available

RELEASE OF PARASITES

A close check was kept on the egg deposition in cane and in the earliest corn to ascertain when parasites should be released When dead hearts of cane and stalks of corn were split especially those that were stunted pupal skins found gave an indication of the number of moth that had emerged and were dppositing eggs for the second generation The parasites were released when three or more clusters of unhatched second-generation eggs could be found in an hours search

In some fields three or more batches of unhatched eggs laid by moths from overwintering borers could be found in an hour during April but there was a period in t1ay or early in June when there were very few eggs in the field It had been recommended that parasites should not be released until borer eggs from the second generation began to appear after which there would be a continuous supply of eggs throughout the remainder of the season

It has also been stated that one release at the rate of about 5000 per acre may be sufficient for the season if rightly timed but that colonizations made after August 1 should be at the rate of ~ OOO per acre (7)

In 1933 parasites were released at the rate of approximately 13000 per acre in canr ancI in addition at the rate of 9000 per acre in corn when this was adjacent to the colonized cane plot The first releases were made between June 10 and 17 in all fields except one It had been planned to make 2 additional similar releases 10 days to 2 weeks TfLilr but this was not donI as there was a decided decrease in the number of borer eggs during the last of June and the first of July due no doubt to the occurrence of a long dry spell over most of the cane section Borer eggs began to increase in numbers again late in Julv and in the first part of August and further releases werl made in all fields in August and some were made as late as September but only because parasites were available Approximately 2404000 parasites were released in 173 acres of cane and 722000 in 80 acres of com Two experiments were carried on in rom to observe the increase in percentage of parasitization and possible difference in yield Other cornfields in which parasites were released borderpd some of the colonized plots of cane In table 6 are ShO11 the dates and approxishymate rates of the releases made in 1933

In 1934 the first release of parasites in the Houma area was made on June 14 and the last of the 10 expprimcnts received parasites on June 25 On June 16 a hurricane swept through the Jeanerette region and whipped and tore mOtit of the corn and cane leaves into long thin shreds destroying practically all t1lC borer eggs present fiS only fresh eggs laid after the storm (ould afterward be found Since this reduced the available supply of host eggs parasite releases there were considembly delayed find in only 2 plots were pornsites released in June-these on June 20 and 23 Only the edge of the storm reached Houma and the borer eggs in that locality were not destroyed

14 TEOHltT]OAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 6-Reletue8 of Trichogramma minutum in flUgarotane and corn in Loui8iana 1933

IN SUGAROANe

Parasites releaoed on d[ltes specified Size u~ I---r------------------I Tlltal ReleasedPlot No per serlgtplot JU~ltl July 4-8 Aug Aug Aug Sept4-4l released

10-17 5-10 14-19 24-29

Acre Number Number NuPIoo Number Numb Numb Number Number ~___________ IV 78 SO200 _______ __ 71000 __________ 65000 100000 376200 19019 19___________ 864 14400 __________ 25000 37000 53000 40000 169400 19836

~OO 127__________

1~~ ---74~500- ___ ~~~_ ---95000shy1100 39500 40000 __________

~~ 30000

40000 Jt~ 1091100

~~ 99M

ML 106__________

~~l8 1900

n~ _____________ ~~~_ --iiiOooo75000 _________ bull __________ 50000

~~ 52000

~~~ 177000

19f3J 9316

118________ 7_00 36500 30375 37000 __ _____ 25000 128875 1811

~g~ 1~rl 1t~ --------- ---28~000- 53000 ~g~ ---75000shy m~ M~ 12___________1__________ 789

273 1990012000

260009000

3800014000

4600017000

26000 IM900 52000

1953319MB

L _____ ___ 8____ _______

7_49 824

30000 30000

16000 26000

23000 37000

3000II 30000

00000 123000

13218 14927

Total l7346 58i9OO ~1354000 447000 651OOO 34OOOO 2404275l38OO r

IN OORN

123____ _____ 220 30000 130625 bull__________ bull__ bull ____ _________ 150626 7301 129-130_____ 100 27000 73000 _____________________________ _________ 100000 10000 H2__________ 150 30000 67000 _________bullbull__________________ bull _________ 97000 6467 117________ 180 40000 126500 bull__________ bull___________ bull_______ bull______ _ 165500 9 1M 102_________ 80 39000 92000 _____________________ bull___bull_______ ______ 131000 16375

~~B~re_ U ~~ ~~ 1amp~ Total 8oOlMOOO5r6l25== ======722i25---gm

During July and August additional parasites were released in the 10 plots near Houma More parasites were released in the middle and last part of July in the 2 plots at Jeanerette that received parasites in June and parasites were released the rast of July and the first of August in the remaining 8 plots Approximately 15500 Trichoshygramma were released per acre in the Jeanerett~ area and 18500 per acre in the Houma area It may be noted that the numbers of parasites released were considerably larger than the 5000 per acre in June or 10000 per acre if the release is delayed until later usually recommended by commercial and State agencies Approximately 1390000 parasites were released in 82 acres of cane and a few addishytional thousand in corn adjoining some of the cane plots In table 7 are given the approximate numbers of Trichogramma released per acre in 1934

In some of the tables and in many places in the text the letters P B and C have been used to designate respectively with the experishyment numbers the colonized (parasitized) buffer alld check plots As previously stated a prefixed letter c denotes a cooperative exshyperiment

EXPERUIENTS FOR CONTROL OF SUGARCANE BORER 15

TABLE 7-Releases oj Trichogramma minutum in sugarcane in Loui8iana

JEANERETTE RELESES 1934

Parasites released on dates specified

Size of Total ReleasedPlot No plot relelSlld per acreJune July Aug 2middot6 Aug 6-96-gt3 13-31

----------------------------------- shyAltTt Numbtr Numbltt Number Numhtr Numbtr Numbtr1-P_ _____________ __________ _

784 _______ 105000 105000 13 393 2-P ________ bullbullbullbullbull_bull_bullbullbull 415 50000 12 0411 l-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull_ 382 io~ooo isooo ~~ ~~~~~~~~~- 45000 117804-Pbull_bull ___ bullbullbullbullbullbullbull_bullbull __ 364 69000 18 9565-P bullbullbull __________bullbullbullbullbullbullbullbull__bull 1S5 --10000 i~ ~~~~~ 48000 25 l44 6-P__ bullbullbullbull_bull--__ _ 33S _ __ ___ 49000 __ 49000 146277-Pbullbull _bullbull_bullbull ____ bull __ bullbull___ 614 __ _ 73000 18000 91000 11821S-Pbullbull_bullbull_bullbull_ ___ bull__ bullbull _ __ 690 33000 37000 34000 104 000 150729-P__ bull__ bullbull ____bull __ ______ bull 48000 _____297 48000 161~110-Pbull_bullbull___ bull ____ _bullbull _________ 253 58000 _____ sectIlooo 22925

Total __bullbullbull __ bullbullbull__ _bullbull 4319 20000 210 000 259000 178000 667000 15 laquo3

HOUMA REIEASES 1934

Parasites released on dates specified I Plot No Rize of I Total Released

plot June I July bull AUl released per acreI 14-26 23-31 AuS 1 16-fB

------I~ Numbtr INumbtr ~mber ---Vumbtr Numbtr - cl-Pbullbullbullbullbullbull ______ bull __ ____ 535 64000 [ bullbull__ bullbull _ 32000 bullbull _bullbull _ 96000 17~ c2-Pbullbullbull__ bull____ bullbullbullbullbull_ ___ bullbull __ bullbull 319 29500 30200 ___ _ iI97oo 18 bull iS 3-P_ bull _ ____ ____ __bull _ __ bull 31xl 53000 3I7oo 91700 257M 4-Pbull ___bullbullbullbullbullbull_bullbullbullbull 496 4~7oo __ _ bullbullbullbullbull ___ bullbull _ 31500 SI2oo 16371 S-P_ __ __ _ ____ bullbull ___ _ 315 5200 0000 1O~00 70000 22222 6-P_ bull ------------- 1 458 70200 9 coo __ _ IG25O 962IiO 21013 7-P_____ bull ___ _bullbull__ 335 19000 24150 _ 11600 54750 16bull 343 S-P ______bull __ _ _______ ____ 324 24100 5700 17760 5121i 52rs5 16261 g-p__ ____bull __ bull__bull ____ _ 337 i 213OO 5900 133~2 10250 5072 15069 1() P ___ bullbull _____bull ____ bull__ bullbull I 4 2~ I 34500middot 24150 00- ll7oo 70350 165-14

1------- -------------------TotaL __ ________bull __ ____ 1 39 III ~1S5001 75700 93292 135925 723417 IS Mil

JRANERETTE RELEASES 1935

II Parasites released Ol dates specified Size of Total ReleRSedPlot No released per arre

16-lil 2amp-30 Aug 7 Au~ 13plot June Jllly

------------middoti----------~----Imiddot-------------~----Arrlt INumbtr Numb NILmbu Numbtr J ]Iumbu Numbtr

3-P_ _________ bull __ _________ 438 _ laquo325 11250 I M575 12688 4-Pbull __________ ___ bull__bullbull___ 399 I 12600 40725 ______ _ ll25O 64515 16184 7-P__ ___ 296 bullbull 00 36450 1--- - 3n450 I 12314S-P______ __ 465 46t)~7 1~875 601121 136119 IO-P __ ___ 286 00 29025 29025 I 10149 cl3-P 2H 16000 292IiO __ 45250 16515 14-P__ __ 299 bull_____ 36900 36900 123Ujc19-P ____ 2 i3 17000 27337 44337 16421 c20-P _________ 2 M 16000 29025 45025 15315

1 TotaL __ _ -24 r 6Uo -zq712 ~~3937i 1 420600fl39ll

16 TECHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 7-Releasea of Trichogramma minutum in augarcane in Louiaiana-Con

ROUM- RELEASES 1935

Parasites released on dates speltled

Plot No Size of 1-------------shyplot

June 14 July 27 Aug 8 -ug Total

released Released per acre

13-14

---------1------------------------ACIt Number Number Number Number Number Number

21-P 22-P 23middotP 24-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull bullbullbullbullbullbull 25-P 26-Pbullbullbullbullbullbullbullbull 27P c30-P c31-P c32middotP

152 319 290 687 185 328 220 262 361 I ()Q

14250 Zl25O 29500 42500 14700 28125

27250 42000 40 AJO 4P300 ~OOO 37000 SO750

21000 45000 tqOOO 42000 41500 83500

48000 57500 bullbullbullbullbullbullbullbull 77100 47600

62500 lIO25O 107500 130800 74200

14R625 98750 57500 77100 47600

41118 34561 37069 19039 40108 45312 H88fl 21947 21357 43670

c33-P 135 3~ 000 bullbullbullbullbullbullbullbull 34 000 25184

Totel 3048 152325 261300 216200 319000 94B825 31111

In 1935 parasites were released at rates of from 10000 to 45000 per acre In the Jeanerette area an average of approximately 14000 Trichogramma were released per acre but in the Houma area the avershyage number per acre was about 31000 The dates and approximate rates of releases made in 1935 are also shown in table 7

Herbert Spencer of the Division of Fruit Insect Investigations of the Bureau of Entomology and Plant Quarantine kindly supplied from Albany Ga all the Trichogramma used in these experiments excepting those supplied by the Louisiana Agricultural Experiment Station for release in cooperative experiments These parasites were all of the dark Louisiana strain being progeny of adults obtained from eggs of Diatraea saccharalis collected in Louisiana

Parasites were requested as needed and disks of cardboard containshying approximately 50000 Sitotroga eggs that had been exposed to parasites were sent usually just after the eggs had turned black A count was made on each card at 2 or more points to obtain the percentshyage of parasitization The cards were cut in halves quarters or thirds as desired and were placed in petri dishes for emergence The day after the parasites began to emerge a sufficiently large number usually had emerged and mated to justify their release The dishes of parasites were protected from the sun and heat while being transported to fields for release It was sometimes necessary to use ice in keeping them cool In the latter case the Trichogramma adults became active a few minutes after the container was placed in the open air

Care was taken to get as even a distribution of the parasites in the field as possible The method used was to open a dish slightly and allow the parasites to escape while the operator was walkin between rows of cane From one to three complete rounds were made in each colonized plot in releasing the parasites The cards containing the parasitized eggs were often retained for another day or two in the dishes after the initial release to allow any parasites that had not emerged to emerge and matr before bein released If however pracshytically all the parasites had emerged the cards were torn into small pieces and placed on various cftne stalks

EXPERUIENTS FOR CONmOL OF SUGAROANE BORER 17

RATE OF PARASITIZATION

Examinations for borer egg clusters were begun in April each year Additional examinations wera made at intervals of 2 or 3 weeks thereshyafter until the middle or end of September A record was kept of all egg clusters collected In 1933 the percentage of parasitization was based only on eggs from which neither borers had hatched nor parashysites had emerged In 1934 and 1935 the percentage of parasitization was obtained on eggs from which borers had hatched or parasites had emer~ed as well as on eggs from which neither borers had hatched nor parasites had emerged The parasitization was usually higher in the unhatched clusters However the rate of parasitization between colonized buffer and check plots ran in approlmately the same proportion for both groups This can be seen in tables 9 and 10

TABLE 8-Data on the parasitization of eggs of the sugarcane borer by Trichogramma minutum Louisiana 1988

EXPERIMENTS IN SUGARCANE

I Colonized areas Buffer areas 1 Check areas

Date examined Total I~B~Sit

II

Total ~a~it1 Total 1 ~a~itmiddot I eggs IzatlOn I eggs Izatlon eggs IZ8t10n

-Ap-r-----24--bull-bullbull---bullbull-bullbull-bull--bullbull-bull-bullbull----bullbull-bullbull--bullrN-um-2-b~-~ t Perc~~~ ~ Numb3~ Perc~~~ INumf~ IPtTCt~~ 0

May 1-15bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __ 0 I -0 Imiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot bullbull- bullbull 57 0 May 19-Jlwe L bullbullbullbullbullbullbull_ 51 0 _bullbull 1 44 0 June 5-16bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 1 1038 33 U5 0 66 0 June 26-1uly 5 428 14 __ _ bullbull __ 202 31 July 10-13 bullbull 138 l 0 164 134 lui) 18-29bull _bullbull _bullbullbullbullbullbullbullbullbull _ 766 t 18 - bullbullbullbullbull _ 541 52 July 31-Aug 17bullbullbull __ bull_bullbullbullbullbullbull_bullbullbullbull _ 17s- 171 189 101 1727 219 Aug I8-Sept 8bullbullbullbullbullbull -bullbullbullbullbullbull _1 112741 695 699 961 7032 677 ScPt12-25bullbullbullbullbull _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull j 19149 864 2355 923 13598 876 Sept 26-28bullbullbullbull _bullbullbull _ 6211 903 1545 925 5037 867

EXPERIMENTS IN CORN

56 71 o 0

483 178 2i3 1000

1 Not all oC the buffer arrAS were examined when colonized and check Breas were examinerl

Usually 1 man-hour of search was made for borer egg clusters in each of the colonized buffer and check plots with the exception that early in the season when eggs were scarce and while a large number of plots were under comiideration sometimes only 30 minutes was spent in each plot At the time of collection the egg clusters were divided into four groups as follows (1) Parasitized clusters from whch no insects had emerged (2) parasitized clusters from which emergence had begun (3) unparasitized clusters in which no eggs had hatched and (4) unparasitized clusters in which some or all of the eggs had hatched The eggshells of the completely hatched or emerged clusters vmiddotere counted at the time of collection or later The parashysitized eggs of the unemerged clusters were counted immediately or placed in an ice box until counted The unhatched and apparently nonparasitized eggs were held for at least 4 days then examined or

+45990-41--3

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

12 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

100 f~et of row in 20 scattered locations in each of the colonized buffer and check plots or 6000 feet for each experiment was examshyined and measured for gaps The gaps were recorded in groups of 6 inches above the 18-inch gap Those gaps measuring between 18 and 24 inches would fall in group 1 with an average of 175 feet those between 24 and 30 inches in group 2 with an average of 225 feet and so on From the total of the gap measurements and the

total number of feet exshyNORTH amined the percentage

of gaps was obtained Gap counts were made

CO81 FIRSTshySTUBBLE CANE CO281 FIRST-STUBBLE CANE SOYBEANS in all canefields that

were being considered for use in the Trichoshygramma experiments

Nearly twice as manyROAD fields as would be used

t 1521 ACRES for the experiments I were tentatively selectshyI

I ed each26 P 1155 ACRES early season I During subsequent

CO281 FIRSTshy~

examinations somet STUBBLE CANE I 1814 ACRES fields had to be elimishy

I nated becalise of an I

uneven stand others because of exceptional-

I SOYBEANS ly light infestations of

1864 ACRES

I I I 2395 ACRES borers and others ~ I because gap measureshy

ments indicated thatt I 2391 the stand was not unishyACRES I form The study of a I

26 C large number of fields I and the checking of theI 2366 ACRES I progress of cane growth ~ and borer infestation

co 281 FIRST-STUBBLE CANE SOYBEANS from the first of the season to the time when they were ready

FIGURE I-Typical lay-out of a Trichogramma ex- for parasites gave a periment in a field of Co 281 first-stubble cane better opportunity to as conducted during 1934 and 1935 at New Hope select fields that were Plantation Lafourche Parish La 26P represents comparable for use in the two cuts on which the parasites were released in exp~riment 26 26B the corresponding buffer the experiments than area 26C the ~heck could be had by waitshy

ing un til moths of the second generation were laying eggs and selecting the plots then or even later Fields were selected where the borers were usually most numerous

The immediate enviionments of the fields used were also considered care being taken to see that where possible the colonized and check areas were bordered by a similar kind of crop A diagram showing the plan of an experiment is given in figure 1 This is typical of the experimental fields used in 1934 and 1935 In some cases however

13 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

the colonized plot or the check plot cOJisisted of only one cut instead of two The buffer ranged from two to five cuts depending on the size of the field available

RELEASE OF PARASITES

A close check was kept on the egg deposition in cane and in the earliest corn to ascertain when parasites should be released When dead hearts of cane and stalks of corn were split especially those that were stunted pupal skins found gave an indication of the number of moth that had emerged and were dppositing eggs for the second generation The parasites were released when three or more clusters of unhatched second-generation eggs could be found in an hours search

In some fields three or more batches of unhatched eggs laid by moths from overwintering borers could be found in an hour during April but there was a period in t1ay or early in June when there were very few eggs in the field It had been recommended that parasites should not be released until borer eggs from the second generation began to appear after which there would be a continuous supply of eggs throughout the remainder of the season

It has also been stated that one release at the rate of about 5000 per acre may be sufficient for the season if rightly timed but that colonizations made after August 1 should be at the rate of ~ OOO per acre (7)

In 1933 parasites were released at the rate of approximately 13000 per acre in canr ancI in addition at the rate of 9000 per acre in corn when this was adjacent to the colonized cane plot The first releases were made between June 10 and 17 in all fields except one It had been planned to make 2 additional similar releases 10 days to 2 weeks TfLilr but this was not donI as there was a decided decrease in the number of borer eggs during the last of June and the first of July due no doubt to the occurrence of a long dry spell over most of the cane section Borer eggs began to increase in numbers again late in Julv and in the first part of August and further releases werl made in all fields in August and some were made as late as September but only because parasites were available Approximately 2404000 parasites were released in 173 acres of cane and 722000 in 80 acres of com Two experiments were carried on in rom to observe the increase in percentage of parasitization and possible difference in yield Other cornfields in which parasites were released borderpd some of the colonized plots of cane In table 6 are ShO11 the dates and approxishymate rates of the releases made in 1933

In 1934 the first release of parasites in the Houma area was made on June 14 and the last of the 10 expprimcnts received parasites on June 25 On June 16 a hurricane swept through the Jeanerette region and whipped and tore mOtit of the corn and cane leaves into long thin shreds destroying practically all t1lC borer eggs present fiS only fresh eggs laid after the storm (ould afterward be found Since this reduced the available supply of host eggs parasite releases there were considembly delayed find in only 2 plots were pornsites released in June-these on June 20 and 23 Only the edge of the storm reached Houma and the borer eggs in that locality were not destroyed

14 TEOHltT]OAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 6-Reletue8 of Trichogramma minutum in flUgarotane and corn in Loui8iana 1933

IN SUGAROANe

Parasites releaoed on d[ltes specified Size u~ I---r------------------I Tlltal ReleasedPlot No per serlgtplot JU~ltl July 4-8 Aug Aug Aug Sept4-4l released

10-17 5-10 14-19 24-29

Acre Number Number NuPIoo Number Numb Numb Number Number ~___________ IV 78 SO200 _______ __ 71000 __________ 65000 100000 376200 19019 19___________ 864 14400 __________ 25000 37000 53000 40000 169400 19836

~OO 127__________

1~~ ---74~500- ___ ~~~_ ---95000shy1100 39500 40000 __________

~~ 30000

40000 Jt~ 1091100

~~ 99M

ML 106__________

~~l8 1900

n~ _____________ ~~~_ --iiiOooo75000 _________ bull __________ 50000

~~ 52000

~~~ 177000

19f3J 9316

118________ 7_00 36500 30375 37000 __ _____ 25000 128875 1811

~g~ 1~rl 1t~ --------- ---28~000- 53000 ~g~ ---75000shy m~ M~ 12___________1__________ 789

273 1990012000

260009000

3800014000

4600017000

26000 IM900 52000

1953319MB

L _____ ___ 8____ _______

7_49 824

30000 30000

16000 26000

23000 37000

3000II 30000

00000 123000

13218 14927

Total l7346 58i9OO ~1354000 447000 651OOO 34OOOO 2404275l38OO r

IN OORN

123____ _____ 220 30000 130625 bull__________ bull__ bull ____ _________ 150626 7301 129-130_____ 100 27000 73000 _____________________________ _________ 100000 10000 H2__________ 150 30000 67000 _________bullbull__________________ bull _________ 97000 6467 117________ 180 40000 126500 bull__________ bull___________ bull_______ bull______ _ 165500 9 1M 102_________ 80 39000 92000 _____________________ bull___bull_______ ______ 131000 16375

~~B~re_ U ~~ ~~ 1amp~ Total 8oOlMOOO5r6l25== ======722i25---gm

During July and August additional parasites were released in the 10 plots near Houma More parasites were released in the middle and last part of July in the 2 plots at Jeanerette that received parasites in June and parasites were released the rast of July and the first of August in the remaining 8 plots Approximately 15500 Trichoshygramma were released per acre in the Jeanerett~ area and 18500 per acre in the Houma area It may be noted that the numbers of parasites released were considerably larger than the 5000 per acre in June or 10000 per acre if the release is delayed until later usually recommended by commercial and State agencies Approximately 1390000 parasites were released in 82 acres of cane and a few addishytional thousand in corn adjoining some of the cane plots In table 7 are given the approximate numbers of Trichogramma released per acre in 1934

In some of the tables and in many places in the text the letters P B and C have been used to designate respectively with the experishyment numbers the colonized (parasitized) buffer alld check plots As previously stated a prefixed letter c denotes a cooperative exshyperiment

EXPERUIENTS FOR CONTROL OF SUGARCANE BORER 15

TABLE 7-Releases oj Trichogramma minutum in sugarcane in Loui8iana

JEANERETTE RELESES 1934

Parasites released on dates specified

Size of Total ReleasedPlot No plot relelSlld per acreJune July Aug 2middot6 Aug 6-96-gt3 13-31

----------------------------------- shyAltTt Numbtr Numbltt Number Numhtr Numbtr Numbtr1-P_ _____________ __________ _

784 _______ 105000 105000 13 393 2-P ________ bullbullbullbullbull_bull_bullbullbull 415 50000 12 0411 l-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull_ 382 io~ooo isooo ~~ ~~~~~~~~~- 45000 117804-Pbull_bull ___ bullbullbullbullbullbullbull_bullbull __ 364 69000 18 9565-P bullbullbull __________bullbullbullbullbullbullbullbull__bull 1S5 --10000 i~ ~~~~~ 48000 25 l44 6-P__ bullbullbullbull_bull--__ _ 33S _ __ ___ 49000 __ 49000 146277-Pbullbull _bullbull_bullbull ____ bull __ bullbull___ 614 __ _ 73000 18000 91000 11821S-Pbullbull_bullbull_bullbull_ ___ bull__ bullbull _ __ 690 33000 37000 34000 104 000 150729-P__ bull__ bullbull ____bull __ ______ bull 48000 _____297 48000 161~110-Pbull_bullbull___ bull ____ _bullbull _________ 253 58000 _____ sectIlooo 22925

Total __bullbullbull __ bullbullbull__ _bullbull 4319 20000 210 000 259000 178000 667000 15 laquo3

HOUMA REIEASES 1934

Parasites released on dates specified I Plot No Rize of I Total Released

plot June I July bull AUl released per acreI 14-26 23-31 AuS 1 16-fB

------I~ Numbtr INumbtr ~mber ---Vumbtr Numbtr - cl-Pbullbullbullbullbullbull ______ bull __ ____ 535 64000 [ bullbull__ bullbull _ 32000 bullbull _bullbull _ 96000 17~ c2-Pbullbullbull__ bull____ bullbullbullbullbull_ ___ bullbull __ bullbull 319 29500 30200 ___ _ iI97oo 18 bull iS 3-P_ bull _ ____ ____ __bull _ __ bull 31xl 53000 3I7oo 91700 257M 4-Pbull ___bullbullbullbullbullbull_bullbullbullbull 496 4~7oo __ _ bullbullbullbullbull ___ bullbull _ 31500 SI2oo 16371 S-P_ __ __ _ ____ bullbull ___ _ 315 5200 0000 1O~00 70000 22222 6-P_ bull ------------- 1 458 70200 9 coo __ _ IG25O 962IiO 21013 7-P_____ bull ___ _bullbull__ 335 19000 24150 _ 11600 54750 16bull 343 S-P ______bull __ _ _______ ____ 324 24100 5700 17760 5121i 52rs5 16261 g-p__ ____bull __ bull__bull ____ _ 337 i 213OO 5900 133~2 10250 5072 15069 1() P ___ bullbull _____bull ____ bull__ bullbull I 4 2~ I 34500middot 24150 00- ll7oo 70350 165-14

1------- -------------------TotaL __ ________bull __ ____ 1 39 III ~1S5001 75700 93292 135925 723417 IS Mil

JRANERETTE RELEASES 1935

II Parasites released Ol dates specified Size of Total ReleRSedPlot No released per arre

16-lil 2amp-30 Aug 7 Au~ 13plot June Jllly

------------middoti----------~----Imiddot-------------~----Arrlt INumbtr Numb NILmbu Numbtr J ]Iumbu Numbtr

3-P_ _________ bull __ _________ 438 _ laquo325 11250 I M575 12688 4-Pbull __________ ___ bull__bullbull___ 399 I 12600 40725 ______ _ ll25O 64515 16184 7-P__ ___ 296 bullbull 00 36450 1--- - 3n450 I 12314S-P______ __ 465 46t)~7 1~875 601121 136119 IO-P __ ___ 286 00 29025 29025 I 10149 cl3-P 2H 16000 292IiO __ 45250 16515 14-P__ __ 299 bull_____ 36900 36900 123Ujc19-P ____ 2 i3 17000 27337 44337 16421 c20-P _________ 2 M 16000 29025 45025 15315

1 TotaL __ _ -24 r 6Uo -zq712 ~~3937i 1 420600fl39ll

16 TECHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 7-Releasea of Trichogramma minutum in augarcane in Louiaiana-Con

ROUM- RELEASES 1935

Parasites released on dates speltled

Plot No Size of 1-------------shyplot

June 14 July 27 Aug 8 -ug Total

released Released per acre

13-14

---------1------------------------ACIt Number Number Number Number Number Number

21-P 22-P 23middotP 24-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull bullbullbullbullbullbull 25-P 26-Pbullbullbullbullbullbullbullbull 27P c30-P c31-P c32middotP

152 319 290 687 185 328 220 262 361 I ()Q

14250 Zl25O 29500 42500 14700 28125

27250 42000 40 AJO 4P300 ~OOO 37000 SO750

21000 45000 tqOOO 42000 41500 83500

48000 57500 bullbullbullbullbullbullbullbull 77100 47600

62500 lIO25O 107500 130800 74200

14R625 98750 57500 77100 47600

41118 34561 37069 19039 40108 45312 H88fl 21947 21357 43670

c33-P 135 3~ 000 bullbullbullbullbullbullbullbull 34 000 25184

Totel 3048 152325 261300 216200 319000 94B825 31111

In 1935 parasites were released at rates of from 10000 to 45000 per acre In the Jeanerette area an average of approximately 14000 Trichogramma were released per acre but in the Houma area the avershyage number per acre was about 31000 The dates and approximate rates of releases made in 1935 are also shown in table 7

Herbert Spencer of the Division of Fruit Insect Investigations of the Bureau of Entomology and Plant Quarantine kindly supplied from Albany Ga all the Trichogramma used in these experiments excepting those supplied by the Louisiana Agricultural Experiment Station for release in cooperative experiments These parasites were all of the dark Louisiana strain being progeny of adults obtained from eggs of Diatraea saccharalis collected in Louisiana

Parasites were requested as needed and disks of cardboard containshying approximately 50000 Sitotroga eggs that had been exposed to parasites were sent usually just after the eggs had turned black A count was made on each card at 2 or more points to obtain the percentshyage of parasitization The cards were cut in halves quarters or thirds as desired and were placed in petri dishes for emergence The day after the parasites began to emerge a sufficiently large number usually had emerged and mated to justify their release The dishes of parasites were protected from the sun and heat while being transported to fields for release It was sometimes necessary to use ice in keeping them cool In the latter case the Trichogramma adults became active a few minutes after the container was placed in the open air

Care was taken to get as even a distribution of the parasites in the field as possible The method used was to open a dish slightly and allow the parasites to escape while the operator was walkin between rows of cane From one to three complete rounds were made in each colonized plot in releasing the parasites The cards containing the parasitized eggs were often retained for another day or two in the dishes after the initial release to allow any parasites that had not emerged to emerge and matr before bein released If however pracshytically all the parasites had emerged the cards were torn into small pieces and placed on various cftne stalks

EXPERUIENTS FOR CONmOL OF SUGAROANE BORER 17

RATE OF PARASITIZATION

Examinations for borer egg clusters were begun in April each year Additional examinations wera made at intervals of 2 or 3 weeks thereshyafter until the middle or end of September A record was kept of all egg clusters collected In 1933 the percentage of parasitization was based only on eggs from which neither borers had hatched nor parashysites had emerged In 1934 and 1935 the percentage of parasitization was obtained on eggs from which borers had hatched or parasites had emer~ed as well as on eggs from which neither borers had hatched nor parasites had emerged The parasitization was usually higher in the unhatched clusters However the rate of parasitization between colonized buffer and check plots ran in approlmately the same proportion for both groups This can be seen in tables 9 and 10

TABLE 8-Data on the parasitization of eggs of the sugarcane borer by Trichogramma minutum Louisiana 1988

EXPERIMENTS IN SUGARCANE

I Colonized areas Buffer areas 1 Check areas

Date examined Total I~B~Sit

II

Total ~a~it1 Total 1 ~a~itmiddot I eggs IzatlOn I eggs Izatlon eggs IZ8t10n

-Ap-r-----24--bull-bullbull---bullbull-bullbull-bull--bullbull-bull-bullbull----bullbull-bullbull--bullrN-um-2-b~-~ t Perc~~~ ~ Numb3~ Perc~~~ INumf~ IPtTCt~~ 0

May 1-15bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __ 0 I -0 Imiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot bullbull- bullbull 57 0 May 19-Jlwe L bullbullbullbullbullbullbull_ 51 0 _bullbull 1 44 0 June 5-16bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 1 1038 33 U5 0 66 0 June 26-1uly 5 428 14 __ _ bullbull __ 202 31 July 10-13 bullbull 138 l 0 164 134 lui) 18-29bull _bullbull _bullbullbullbullbullbullbullbullbull _ 766 t 18 - bullbullbullbullbull _ 541 52 July 31-Aug 17bullbullbull __ bull_bullbullbullbullbullbull_bullbullbullbull _ 17s- 171 189 101 1727 219 Aug I8-Sept 8bullbullbullbullbullbull -bullbullbullbullbullbull _1 112741 695 699 961 7032 677 ScPt12-25bullbullbullbullbull _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull j 19149 864 2355 923 13598 876 Sept 26-28bullbullbullbull _bullbullbull _ 6211 903 1545 925 5037 867

EXPERIMENTS IN CORN

56 71 o 0

483 178 2i3 1000

1 Not all oC the buffer arrAS were examined when colonized and check Breas were examinerl

Usually 1 man-hour of search was made for borer egg clusters in each of the colonized buffer and check plots with the exception that early in the season when eggs were scarce and while a large number of plots were under comiideration sometimes only 30 minutes was spent in each plot At the time of collection the egg clusters were divided into four groups as follows (1) Parasitized clusters from whch no insects had emerged (2) parasitized clusters from which emergence had begun (3) unparasitized clusters in which no eggs had hatched and (4) unparasitized clusters in which some or all of the eggs had hatched The eggshells of the completely hatched or emerged clusters vmiddotere counted at the time of collection or later The parashysitized eggs of the unemerged clusters were counted immediately or placed in an ice box until counted The unhatched and apparently nonparasitized eggs were held for at least 4 days then examined or

+45990-41--3

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

13 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

the colonized plot or the check plot cOJisisted of only one cut instead of two The buffer ranged from two to five cuts depending on the size of the field available

RELEASE OF PARASITES

A close check was kept on the egg deposition in cane and in the earliest corn to ascertain when parasites should be released When dead hearts of cane and stalks of corn were split especially those that were stunted pupal skins found gave an indication of the number of moth that had emerged and were dppositing eggs for the second generation The parasites were released when three or more clusters of unhatched second-generation eggs could be found in an hours search

In some fields three or more batches of unhatched eggs laid by moths from overwintering borers could be found in an hour during April but there was a period in t1ay or early in June when there were very few eggs in the field It had been recommended that parasites should not be released until borer eggs from the second generation began to appear after which there would be a continuous supply of eggs throughout the remainder of the season

It has also been stated that one release at the rate of about 5000 per acre may be sufficient for the season if rightly timed but that colonizations made after August 1 should be at the rate of ~ OOO per acre (7)

In 1933 parasites were released at the rate of approximately 13000 per acre in canr ancI in addition at the rate of 9000 per acre in corn when this was adjacent to the colonized cane plot The first releases were made between June 10 and 17 in all fields except one It had been planned to make 2 additional similar releases 10 days to 2 weeks TfLilr but this was not donI as there was a decided decrease in the number of borer eggs during the last of June and the first of July due no doubt to the occurrence of a long dry spell over most of the cane section Borer eggs began to increase in numbers again late in Julv and in the first part of August and further releases werl made in all fields in August and some were made as late as September but only because parasites were available Approximately 2404000 parasites were released in 173 acres of cane and 722000 in 80 acres of com Two experiments were carried on in rom to observe the increase in percentage of parasitization and possible difference in yield Other cornfields in which parasites were released borderpd some of the colonized plots of cane In table 6 are ShO11 the dates and approxishymate rates of the releases made in 1933

In 1934 the first release of parasites in the Houma area was made on June 14 and the last of the 10 expprimcnts received parasites on June 25 On June 16 a hurricane swept through the Jeanerette region and whipped and tore mOtit of the corn and cane leaves into long thin shreds destroying practically all t1lC borer eggs present fiS only fresh eggs laid after the storm (ould afterward be found Since this reduced the available supply of host eggs parasite releases there were considembly delayed find in only 2 plots were pornsites released in June-these on June 20 and 23 Only the edge of the storm reached Houma and the borer eggs in that locality were not destroyed

14 TEOHltT]OAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 6-Reletue8 of Trichogramma minutum in flUgarotane and corn in Loui8iana 1933

IN SUGAROANe

Parasites releaoed on d[ltes specified Size u~ I---r------------------I Tlltal ReleasedPlot No per serlgtplot JU~ltl July 4-8 Aug Aug Aug Sept4-4l released

10-17 5-10 14-19 24-29

Acre Number Number NuPIoo Number Numb Numb Number Number ~___________ IV 78 SO200 _______ __ 71000 __________ 65000 100000 376200 19019 19___________ 864 14400 __________ 25000 37000 53000 40000 169400 19836

~OO 127__________

1~~ ---74~500- ___ ~~~_ ---95000shy1100 39500 40000 __________

~~ 30000

40000 Jt~ 1091100

~~ 99M

ML 106__________

~~l8 1900

n~ _____________ ~~~_ --iiiOooo75000 _________ bull __________ 50000

~~ 52000

~~~ 177000

19f3J 9316

118________ 7_00 36500 30375 37000 __ _____ 25000 128875 1811

~g~ 1~rl 1t~ --------- ---28~000- 53000 ~g~ ---75000shy m~ M~ 12___________1__________ 789

273 1990012000

260009000

3800014000

4600017000

26000 IM900 52000

1953319MB

L _____ ___ 8____ _______

7_49 824

30000 30000

16000 26000

23000 37000

3000II 30000

00000 123000

13218 14927

Total l7346 58i9OO ~1354000 447000 651OOO 34OOOO 2404275l38OO r

IN OORN

123____ _____ 220 30000 130625 bull__________ bull__ bull ____ _________ 150626 7301 129-130_____ 100 27000 73000 _____________________________ _________ 100000 10000 H2__________ 150 30000 67000 _________bullbull__________________ bull _________ 97000 6467 117________ 180 40000 126500 bull__________ bull___________ bull_______ bull______ _ 165500 9 1M 102_________ 80 39000 92000 _____________________ bull___bull_______ ______ 131000 16375

~~B~re_ U ~~ ~~ 1amp~ Total 8oOlMOOO5r6l25== ======722i25---gm

During July and August additional parasites were released in the 10 plots near Houma More parasites were released in the middle and last part of July in the 2 plots at Jeanerette that received parasites in June and parasites were released the rast of July and the first of August in the remaining 8 plots Approximately 15500 Trichoshygramma were released per acre in the Jeanerett~ area and 18500 per acre in the Houma area It may be noted that the numbers of parasites released were considerably larger than the 5000 per acre in June or 10000 per acre if the release is delayed until later usually recommended by commercial and State agencies Approximately 1390000 parasites were released in 82 acres of cane and a few addishytional thousand in corn adjoining some of the cane plots In table 7 are given the approximate numbers of Trichogramma released per acre in 1934

In some of the tables and in many places in the text the letters P B and C have been used to designate respectively with the experishyment numbers the colonized (parasitized) buffer alld check plots As previously stated a prefixed letter c denotes a cooperative exshyperiment

EXPERUIENTS FOR CONTROL OF SUGARCANE BORER 15

TABLE 7-Releases oj Trichogramma minutum in sugarcane in Loui8iana

JEANERETTE RELESES 1934

Parasites released on dates specified

Size of Total ReleasedPlot No plot relelSlld per acreJune July Aug 2middot6 Aug 6-96-gt3 13-31

----------------------------------- shyAltTt Numbtr Numbltt Number Numhtr Numbtr Numbtr1-P_ _____________ __________ _

784 _______ 105000 105000 13 393 2-P ________ bullbullbullbullbull_bull_bullbullbull 415 50000 12 0411 l-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull_ 382 io~ooo isooo ~~ ~~~~~~~~~- 45000 117804-Pbull_bull ___ bullbullbullbullbullbullbull_bullbull __ 364 69000 18 9565-P bullbullbull __________bullbullbullbullbullbullbullbull__bull 1S5 --10000 i~ ~~~~~ 48000 25 l44 6-P__ bullbullbullbull_bull--__ _ 33S _ __ ___ 49000 __ 49000 146277-Pbullbull _bullbull_bullbull ____ bull __ bullbull___ 614 __ _ 73000 18000 91000 11821S-Pbullbull_bullbull_bullbull_ ___ bull__ bullbull _ __ 690 33000 37000 34000 104 000 150729-P__ bull__ bullbull ____bull __ ______ bull 48000 _____297 48000 161~110-Pbull_bullbull___ bull ____ _bullbull _________ 253 58000 _____ sectIlooo 22925

Total __bullbullbull __ bullbullbull__ _bullbull 4319 20000 210 000 259000 178000 667000 15 laquo3

HOUMA REIEASES 1934

Parasites released on dates specified I Plot No Rize of I Total Released

plot June I July bull AUl released per acreI 14-26 23-31 AuS 1 16-fB

------I~ Numbtr INumbtr ~mber ---Vumbtr Numbtr - cl-Pbullbullbullbullbullbull ______ bull __ ____ 535 64000 [ bullbull__ bullbull _ 32000 bullbull _bullbull _ 96000 17~ c2-Pbullbullbull__ bull____ bullbullbullbullbull_ ___ bullbull __ bullbull 319 29500 30200 ___ _ iI97oo 18 bull iS 3-P_ bull _ ____ ____ __bull _ __ bull 31xl 53000 3I7oo 91700 257M 4-Pbull ___bullbullbullbullbullbull_bullbullbullbull 496 4~7oo __ _ bullbullbullbullbull ___ bullbull _ 31500 SI2oo 16371 S-P_ __ __ _ ____ bullbull ___ _ 315 5200 0000 1O~00 70000 22222 6-P_ bull ------------- 1 458 70200 9 coo __ _ IG25O 962IiO 21013 7-P_____ bull ___ _bullbull__ 335 19000 24150 _ 11600 54750 16bull 343 S-P ______bull __ _ _______ ____ 324 24100 5700 17760 5121i 52rs5 16261 g-p__ ____bull __ bull__bull ____ _ 337 i 213OO 5900 133~2 10250 5072 15069 1() P ___ bullbull _____bull ____ bull__ bullbull I 4 2~ I 34500middot 24150 00- ll7oo 70350 165-14

1------- -------------------TotaL __ ________bull __ ____ 1 39 III ~1S5001 75700 93292 135925 723417 IS Mil

JRANERETTE RELEASES 1935

II Parasites released Ol dates specified Size of Total ReleRSedPlot No released per arre

16-lil 2amp-30 Aug 7 Au~ 13plot June Jllly

------------middoti----------~----Imiddot-------------~----Arrlt INumbtr Numb NILmbu Numbtr J ]Iumbu Numbtr

3-P_ _________ bull __ _________ 438 _ laquo325 11250 I M575 12688 4-Pbull __________ ___ bull__bullbull___ 399 I 12600 40725 ______ _ ll25O 64515 16184 7-P__ ___ 296 bullbull 00 36450 1--- - 3n450 I 12314S-P______ __ 465 46t)~7 1~875 601121 136119 IO-P __ ___ 286 00 29025 29025 I 10149 cl3-P 2H 16000 292IiO __ 45250 16515 14-P__ __ 299 bull_____ 36900 36900 123Ujc19-P ____ 2 i3 17000 27337 44337 16421 c20-P _________ 2 M 16000 29025 45025 15315

1 TotaL __ _ -24 r 6Uo -zq712 ~~3937i 1 420600fl39ll

16 TECHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 7-Releasea of Trichogramma minutum in augarcane in Louiaiana-Con

ROUM- RELEASES 1935

Parasites released on dates speltled

Plot No Size of 1-------------shyplot

June 14 July 27 Aug 8 -ug Total

released Released per acre

13-14

---------1------------------------ACIt Number Number Number Number Number Number

21-P 22-P 23middotP 24-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull bullbullbullbullbullbull 25-P 26-Pbullbullbullbullbullbullbullbull 27P c30-P c31-P c32middotP

152 319 290 687 185 328 220 262 361 I ()Q

14250 Zl25O 29500 42500 14700 28125

27250 42000 40 AJO 4P300 ~OOO 37000 SO750

21000 45000 tqOOO 42000 41500 83500

48000 57500 bullbullbullbullbullbullbullbull 77100 47600

62500 lIO25O 107500 130800 74200

14R625 98750 57500 77100 47600

41118 34561 37069 19039 40108 45312 H88fl 21947 21357 43670

c33-P 135 3~ 000 bullbullbullbullbullbullbullbull 34 000 25184

Totel 3048 152325 261300 216200 319000 94B825 31111

In 1935 parasites were released at rates of from 10000 to 45000 per acre In the Jeanerette area an average of approximately 14000 Trichogramma were released per acre but in the Houma area the avershyage number per acre was about 31000 The dates and approximate rates of releases made in 1935 are also shown in table 7

Herbert Spencer of the Division of Fruit Insect Investigations of the Bureau of Entomology and Plant Quarantine kindly supplied from Albany Ga all the Trichogramma used in these experiments excepting those supplied by the Louisiana Agricultural Experiment Station for release in cooperative experiments These parasites were all of the dark Louisiana strain being progeny of adults obtained from eggs of Diatraea saccharalis collected in Louisiana

Parasites were requested as needed and disks of cardboard containshying approximately 50000 Sitotroga eggs that had been exposed to parasites were sent usually just after the eggs had turned black A count was made on each card at 2 or more points to obtain the percentshyage of parasitization The cards were cut in halves quarters or thirds as desired and were placed in petri dishes for emergence The day after the parasites began to emerge a sufficiently large number usually had emerged and mated to justify their release The dishes of parasites were protected from the sun and heat while being transported to fields for release It was sometimes necessary to use ice in keeping them cool In the latter case the Trichogramma adults became active a few minutes after the container was placed in the open air

Care was taken to get as even a distribution of the parasites in the field as possible The method used was to open a dish slightly and allow the parasites to escape while the operator was walkin between rows of cane From one to three complete rounds were made in each colonized plot in releasing the parasites The cards containing the parasitized eggs were often retained for another day or two in the dishes after the initial release to allow any parasites that had not emerged to emerge and matr before bein released If however pracshytically all the parasites had emerged the cards were torn into small pieces and placed on various cftne stalks

EXPERUIENTS FOR CONmOL OF SUGAROANE BORER 17

RATE OF PARASITIZATION

Examinations for borer egg clusters were begun in April each year Additional examinations wera made at intervals of 2 or 3 weeks thereshyafter until the middle or end of September A record was kept of all egg clusters collected In 1933 the percentage of parasitization was based only on eggs from which neither borers had hatched nor parashysites had emerged In 1934 and 1935 the percentage of parasitization was obtained on eggs from which borers had hatched or parasites had emer~ed as well as on eggs from which neither borers had hatched nor parasites had emerged The parasitization was usually higher in the unhatched clusters However the rate of parasitization between colonized buffer and check plots ran in approlmately the same proportion for both groups This can be seen in tables 9 and 10

TABLE 8-Data on the parasitization of eggs of the sugarcane borer by Trichogramma minutum Louisiana 1988

EXPERIMENTS IN SUGARCANE

I Colonized areas Buffer areas 1 Check areas

Date examined Total I~B~Sit

II

Total ~a~it1 Total 1 ~a~itmiddot I eggs IzatlOn I eggs Izatlon eggs IZ8t10n

-Ap-r-----24--bull-bullbull---bullbull-bullbull-bull--bullbull-bull-bullbull----bullbull-bullbull--bullrN-um-2-b~-~ t Perc~~~ ~ Numb3~ Perc~~~ INumf~ IPtTCt~~ 0

May 1-15bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __ 0 I -0 Imiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot bullbull- bullbull 57 0 May 19-Jlwe L bullbullbullbullbullbullbull_ 51 0 _bullbull 1 44 0 June 5-16bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 1 1038 33 U5 0 66 0 June 26-1uly 5 428 14 __ _ bullbull __ 202 31 July 10-13 bullbull 138 l 0 164 134 lui) 18-29bull _bullbull _bullbullbullbullbullbullbullbullbull _ 766 t 18 - bullbullbullbullbull _ 541 52 July 31-Aug 17bullbullbull __ bull_bullbullbullbullbullbull_bullbullbullbull _ 17s- 171 189 101 1727 219 Aug I8-Sept 8bullbullbullbullbullbull -bullbullbullbullbullbull _1 112741 695 699 961 7032 677 ScPt12-25bullbullbullbullbull _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull j 19149 864 2355 923 13598 876 Sept 26-28bullbullbullbull _bullbullbull _ 6211 903 1545 925 5037 867

EXPERIMENTS IN CORN

56 71 o 0

483 178 2i3 1000

1 Not all oC the buffer arrAS were examined when colonized and check Breas were examinerl

Usually 1 man-hour of search was made for borer egg clusters in each of the colonized buffer and check plots with the exception that early in the season when eggs were scarce and while a large number of plots were under comiideration sometimes only 30 minutes was spent in each plot At the time of collection the egg clusters were divided into four groups as follows (1) Parasitized clusters from whch no insects had emerged (2) parasitized clusters from which emergence had begun (3) unparasitized clusters in which no eggs had hatched and (4) unparasitized clusters in which some or all of the eggs had hatched The eggshells of the completely hatched or emerged clusters vmiddotere counted at the time of collection or later The parashysitized eggs of the unemerged clusters were counted immediately or placed in an ice box until counted The unhatched and apparently nonparasitized eggs were held for at least 4 days then examined or

+45990-41--3

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

14 TEOHltT]OAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 6-Reletue8 of Trichogramma minutum in flUgarotane and corn in Loui8iana 1933

IN SUGAROANe

Parasites releaoed on d[ltes specified Size u~ I---r------------------I Tlltal ReleasedPlot No per serlgtplot JU~ltl July 4-8 Aug Aug Aug Sept4-4l released

10-17 5-10 14-19 24-29

Acre Number Number NuPIoo Number Numb Numb Number Number ~___________ IV 78 SO200 _______ __ 71000 __________ 65000 100000 376200 19019 19___________ 864 14400 __________ 25000 37000 53000 40000 169400 19836

~OO 127__________

1~~ ---74~500- ___ ~~~_ ---95000shy1100 39500 40000 __________

~~ 30000

40000 Jt~ 1091100

~~ 99M

ML 106__________

~~l8 1900

n~ _____________ ~~~_ --iiiOooo75000 _________ bull __________ 50000

~~ 52000

~~~ 177000

19f3J 9316

118________ 7_00 36500 30375 37000 __ _____ 25000 128875 1811

~g~ 1~rl 1t~ --------- ---28~000- 53000 ~g~ ---75000shy m~ M~ 12___________1__________ 789

273 1990012000

260009000

3800014000

4600017000

26000 IM900 52000

1953319MB

L _____ ___ 8____ _______

7_49 824

30000 30000

16000 26000

23000 37000

3000II 30000

00000 123000

13218 14927

Total l7346 58i9OO ~1354000 447000 651OOO 34OOOO 2404275l38OO r

IN OORN

123____ _____ 220 30000 130625 bull__________ bull__ bull ____ _________ 150626 7301 129-130_____ 100 27000 73000 _____________________________ _________ 100000 10000 H2__________ 150 30000 67000 _________bullbull__________________ bull _________ 97000 6467 117________ 180 40000 126500 bull__________ bull___________ bull_______ bull______ _ 165500 9 1M 102_________ 80 39000 92000 _____________________ bull___bull_______ ______ 131000 16375

~~B~re_ U ~~ ~~ 1amp~ Total 8oOlMOOO5r6l25== ======722i25---gm

During July and August additional parasites were released in the 10 plots near Houma More parasites were released in the middle and last part of July in the 2 plots at Jeanerette that received parasites in June and parasites were released the rast of July and the first of August in the remaining 8 plots Approximately 15500 Trichoshygramma were released per acre in the Jeanerett~ area and 18500 per acre in the Houma area It may be noted that the numbers of parasites released were considerably larger than the 5000 per acre in June or 10000 per acre if the release is delayed until later usually recommended by commercial and State agencies Approximately 1390000 parasites were released in 82 acres of cane and a few addishytional thousand in corn adjoining some of the cane plots In table 7 are given the approximate numbers of Trichogramma released per acre in 1934

In some of the tables and in many places in the text the letters P B and C have been used to designate respectively with the experishyment numbers the colonized (parasitized) buffer alld check plots As previously stated a prefixed letter c denotes a cooperative exshyperiment

EXPERUIENTS FOR CONTROL OF SUGARCANE BORER 15

TABLE 7-Releases oj Trichogramma minutum in sugarcane in Loui8iana

JEANERETTE RELESES 1934

Parasites released on dates specified

Size of Total ReleasedPlot No plot relelSlld per acreJune July Aug 2middot6 Aug 6-96-gt3 13-31

----------------------------------- shyAltTt Numbtr Numbltt Number Numhtr Numbtr Numbtr1-P_ _____________ __________ _

784 _______ 105000 105000 13 393 2-P ________ bullbullbullbullbull_bull_bullbullbull 415 50000 12 0411 l-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull_ 382 io~ooo isooo ~~ ~~~~~~~~~- 45000 117804-Pbull_bull ___ bullbullbullbullbullbullbull_bullbull __ 364 69000 18 9565-P bullbullbull __________bullbullbullbullbullbullbullbull__bull 1S5 --10000 i~ ~~~~~ 48000 25 l44 6-P__ bullbullbullbull_bull--__ _ 33S _ __ ___ 49000 __ 49000 146277-Pbullbull _bullbull_bullbull ____ bull __ bullbull___ 614 __ _ 73000 18000 91000 11821S-Pbullbull_bullbull_bullbull_ ___ bull__ bullbull _ __ 690 33000 37000 34000 104 000 150729-P__ bull__ bullbull ____bull __ ______ bull 48000 _____297 48000 161~110-Pbull_bullbull___ bull ____ _bullbull _________ 253 58000 _____ sectIlooo 22925

Total __bullbullbull __ bullbullbull__ _bullbull 4319 20000 210 000 259000 178000 667000 15 laquo3

HOUMA REIEASES 1934

Parasites released on dates specified I Plot No Rize of I Total Released

plot June I July bull AUl released per acreI 14-26 23-31 AuS 1 16-fB

------I~ Numbtr INumbtr ~mber ---Vumbtr Numbtr - cl-Pbullbullbullbullbullbull ______ bull __ ____ 535 64000 [ bullbull__ bullbull _ 32000 bullbull _bullbull _ 96000 17~ c2-Pbullbullbull__ bull____ bullbullbullbullbull_ ___ bullbull __ bullbull 319 29500 30200 ___ _ iI97oo 18 bull iS 3-P_ bull _ ____ ____ __bull _ __ bull 31xl 53000 3I7oo 91700 257M 4-Pbull ___bullbullbullbullbullbull_bullbullbullbull 496 4~7oo __ _ bullbullbullbullbull ___ bullbull _ 31500 SI2oo 16371 S-P_ __ __ _ ____ bullbull ___ _ 315 5200 0000 1O~00 70000 22222 6-P_ bull ------------- 1 458 70200 9 coo __ _ IG25O 962IiO 21013 7-P_____ bull ___ _bullbull__ 335 19000 24150 _ 11600 54750 16bull 343 S-P ______bull __ _ _______ ____ 324 24100 5700 17760 5121i 52rs5 16261 g-p__ ____bull __ bull__bull ____ _ 337 i 213OO 5900 133~2 10250 5072 15069 1() P ___ bullbull _____bull ____ bull__ bullbull I 4 2~ I 34500middot 24150 00- ll7oo 70350 165-14

1------- -------------------TotaL __ ________bull __ ____ 1 39 III ~1S5001 75700 93292 135925 723417 IS Mil

JRANERETTE RELEASES 1935

II Parasites released Ol dates specified Size of Total ReleRSedPlot No released per arre

16-lil 2amp-30 Aug 7 Au~ 13plot June Jllly

------------middoti----------~----Imiddot-------------~----Arrlt INumbtr Numb NILmbu Numbtr J ]Iumbu Numbtr

3-P_ _________ bull __ _________ 438 _ laquo325 11250 I M575 12688 4-Pbull __________ ___ bull__bullbull___ 399 I 12600 40725 ______ _ ll25O 64515 16184 7-P__ ___ 296 bullbull 00 36450 1--- - 3n450 I 12314S-P______ __ 465 46t)~7 1~875 601121 136119 IO-P __ ___ 286 00 29025 29025 I 10149 cl3-P 2H 16000 292IiO __ 45250 16515 14-P__ __ 299 bull_____ 36900 36900 123Ujc19-P ____ 2 i3 17000 27337 44337 16421 c20-P _________ 2 M 16000 29025 45025 15315

1 TotaL __ _ -24 r 6Uo -zq712 ~~3937i 1 420600fl39ll

16 TECHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 7-Releasea of Trichogramma minutum in augarcane in Louiaiana-Con

ROUM- RELEASES 1935

Parasites released on dates speltled

Plot No Size of 1-------------shyplot

June 14 July 27 Aug 8 -ug Total

released Released per acre

13-14

---------1------------------------ACIt Number Number Number Number Number Number

21-P 22-P 23middotP 24-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull bullbullbullbullbullbull 25-P 26-Pbullbullbullbullbullbullbullbull 27P c30-P c31-P c32middotP

152 319 290 687 185 328 220 262 361 I ()Q

14250 Zl25O 29500 42500 14700 28125

27250 42000 40 AJO 4P300 ~OOO 37000 SO750

21000 45000 tqOOO 42000 41500 83500

48000 57500 bullbullbullbullbullbullbullbull 77100 47600

62500 lIO25O 107500 130800 74200

14R625 98750 57500 77100 47600

41118 34561 37069 19039 40108 45312 H88fl 21947 21357 43670

c33-P 135 3~ 000 bullbullbullbullbullbullbullbull 34 000 25184

Totel 3048 152325 261300 216200 319000 94B825 31111

In 1935 parasites were released at rates of from 10000 to 45000 per acre In the Jeanerette area an average of approximately 14000 Trichogramma were released per acre but in the Houma area the avershyage number per acre was about 31000 The dates and approximate rates of releases made in 1935 are also shown in table 7

Herbert Spencer of the Division of Fruit Insect Investigations of the Bureau of Entomology and Plant Quarantine kindly supplied from Albany Ga all the Trichogramma used in these experiments excepting those supplied by the Louisiana Agricultural Experiment Station for release in cooperative experiments These parasites were all of the dark Louisiana strain being progeny of adults obtained from eggs of Diatraea saccharalis collected in Louisiana

Parasites were requested as needed and disks of cardboard containshying approximately 50000 Sitotroga eggs that had been exposed to parasites were sent usually just after the eggs had turned black A count was made on each card at 2 or more points to obtain the percentshyage of parasitization The cards were cut in halves quarters or thirds as desired and were placed in petri dishes for emergence The day after the parasites began to emerge a sufficiently large number usually had emerged and mated to justify their release The dishes of parasites were protected from the sun and heat while being transported to fields for release It was sometimes necessary to use ice in keeping them cool In the latter case the Trichogramma adults became active a few minutes after the container was placed in the open air

Care was taken to get as even a distribution of the parasites in the field as possible The method used was to open a dish slightly and allow the parasites to escape while the operator was walkin between rows of cane From one to three complete rounds were made in each colonized plot in releasing the parasites The cards containing the parasitized eggs were often retained for another day or two in the dishes after the initial release to allow any parasites that had not emerged to emerge and matr before bein released If however pracshytically all the parasites had emerged the cards were torn into small pieces and placed on various cftne stalks

EXPERUIENTS FOR CONmOL OF SUGAROANE BORER 17

RATE OF PARASITIZATION

Examinations for borer egg clusters were begun in April each year Additional examinations wera made at intervals of 2 or 3 weeks thereshyafter until the middle or end of September A record was kept of all egg clusters collected In 1933 the percentage of parasitization was based only on eggs from which neither borers had hatched nor parashysites had emerged In 1934 and 1935 the percentage of parasitization was obtained on eggs from which borers had hatched or parasites had emer~ed as well as on eggs from which neither borers had hatched nor parasites had emerged The parasitization was usually higher in the unhatched clusters However the rate of parasitization between colonized buffer and check plots ran in approlmately the same proportion for both groups This can be seen in tables 9 and 10

TABLE 8-Data on the parasitization of eggs of the sugarcane borer by Trichogramma minutum Louisiana 1988

EXPERIMENTS IN SUGARCANE

I Colonized areas Buffer areas 1 Check areas

Date examined Total I~B~Sit

II

Total ~a~it1 Total 1 ~a~itmiddot I eggs IzatlOn I eggs Izatlon eggs IZ8t10n

-Ap-r-----24--bull-bullbull---bullbull-bullbull-bull--bullbull-bull-bullbull----bullbull-bullbull--bullrN-um-2-b~-~ t Perc~~~ ~ Numb3~ Perc~~~ INumf~ IPtTCt~~ 0

May 1-15bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __ 0 I -0 Imiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot bullbull- bullbull 57 0 May 19-Jlwe L bullbullbullbullbullbullbull_ 51 0 _bullbull 1 44 0 June 5-16bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 1 1038 33 U5 0 66 0 June 26-1uly 5 428 14 __ _ bullbull __ 202 31 July 10-13 bullbull 138 l 0 164 134 lui) 18-29bull _bullbull _bullbullbullbullbullbullbullbullbull _ 766 t 18 - bullbullbullbullbull _ 541 52 July 31-Aug 17bullbullbull __ bull_bullbullbullbullbullbull_bullbullbullbull _ 17s- 171 189 101 1727 219 Aug I8-Sept 8bullbullbullbullbullbull -bullbullbullbullbullbull _1 112741 695 699 961 7032 677 ScPt12-25bullbullbullbullbull _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull j 19149 864 2355 923 13598 876 Sept 26-28bullbullbullbull _bullbullbull _ 6211 903 1545 925 5037 867

EXPERIMENTS IN CORN

56 71 o 0

483 178 2i3 1000

1 Not all oC the buffer arrAS were examined when colonized and check Breas were examinerl

Usually 1 man-hour of search was made for borer egg clusters in each of the colonized buffer and check plots with the exception that early in the season when eggs were scarce and while a large number of plots were under comiideration sometimes only 30 minutes was spent in each plot At the time of collection the egg clusters were divided into four groups as follows (1) Parasitized clusters from whch no insects had emerged (2) parasitized clusters from which emergence had begun (3) unparasitized clusters in which no eggs had hatched and (4) unparasitized clusters in which some or all of the eggs had hatched The eggshells of the completely hatched or emerged clusters vmiddotere counted at the time of collection or later The parashysitized eggs of the unemerged clusters were counted immediately or placed in an ice box until counted The unhatched and apparently nonparasitized eggs were held for at least 4 days then examined or

+45990-41--3

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

EXPERUIENTS FOR CONTROL OF SUGARCANE BORER 15

TABLE 7-Releases oj Trichogramma minutum in sugarcane in Loui8iana

JEANERETTE RELESES 1934

Parasites released on dates specified

Size of Total ReleasedPlot No plot relelSlld per acreJune July Aug 2middot6 Aug 6-96-gt3 13-31

----------------------------------- shyAltTt Numbtr Numbltt Number Numhtr Numbtr Numbtr1-P_ _____________ __________ _

784 _______ 105000 105000 13 393 2-P ________ bullbullbullbullbull_bull_bullbullbull 415 50000 12 0411 l-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull_ 382 io~ooo isooo ~~ ~~~~~~~~~- 45000 117804-Pbull_bull ___ bullbullbullbullbullbullbull_bullbull __ 364 69000 18 9565-P bullbullbull __________bullbullbullbullbullbullbullbull__bull 1S5 --10000 i~ ~~~~~ 48000 25 l44 6-P__ bullbullbullbull_bull--__ _ 33S _ __ ___ 49000 __ 49000 146277-Pbullbull _bullbull_bullbull ____ bull __ bullbull___ 614 __ _ 73000 18000 91000 11821S-Pbullbull_bullbull_bullbull_ ___ bull__ bullbull _ __ 690 33000 37000 34000 104 000 150729-P__ bull__ bullbull ____bull __ ______ bull 48000 _____297 48000 161~110-Pbull_bullbull___ bull ____ _bullbull _________ 253 58000 _____ sectIlooo 22925

Total __bullbullbull __ bullbullbull__ _bullbull 4319 20000 210 000 259000 178000 667000 15 laquo3

HOUMA REIEASES 1934

Parasites released on dates specified I Plot No Rize of I Total Released

plot June I July bull AUl released per acreI 14-26 23-31 AuS 1 16-fB

------I~ Numbtr INumbtr ~mber ---Vumbtr Numbtr - cl-Pbullbullbullbullbullbull ______ bull __ ____ 535 64000 [ bullbull__ bullbull _ 32000 bullbull _bullbull _ 96000 17~ c2-Pbullbullbull__ bull____ bullbullbullbullbull_ ___ bullbull __ bullbull 319 29500 30200 ___ _ iI97oo 18 bull iS 3-P_ bull _ ____ ____ __bull _ __ bull 31xl 53000 3I7oo 91700 257M 4-Pbull ___bullbullbullbullbullbull_bullbullbullbull 496 4~7oo __ _ bullbullbullbullbull ___ bullbull _ 31500 SI2oo 16371 S-P_ __ __ _ ____ bullbull ___ _ 315 5200 0000 1O~00 70000 22222 6-P_ bull ------------- 1 458 70200 9 coo __ _ IG25O 962IiO 21013 7-P_____ bull ___ _bullbull__ 335 19000 24150 _ 11600 54750 16bull 343 S-P ______bull __ _ _______ ____ 324 24100 5700 17760 5121i 52rs5 16261 g-p__ ____bull __ bull__bull ____ _ 337 i 213OO 5900 133~2 10250 5072 15069 1() P ___ bullbull _____bull ____ bull__ bullbull I 4 2~ I 34500middot 24150 00- ll7oo 70350 165-14

1------- -------------------TotaL __ ________bull __ ____ 1 39 III ~1S5001 75700 93292 135925 723417 IS Mil

JRANERETTE RELEASES 1935

II Parasites released Ol dates specified Size of Total ReleRSedPlot No released per arre

16-lil 2amp-30 Aug 7 Au~ 13plot June Jllly

------------middoti----------~----Imiddot-------------~----Arrlt INumbtr Numb NILmbu Numbtr J ]Iumbu Numbtr

3-P_ _________ bull __ _________ 438 _ laquo325 11250 I M575 12688 4-Pbull __________ ___ bull__bullbull___ 399 I 12600 40725 ______ _ ll25O 64515 16184 7-P__ ___ 296 bullbull 00 36450 1--- - 3n450 I 12314S-P______ __ 465 46t)~7 1~875 601121 136119 IO-P __ ___ 286 00 29025 29025 I 10149 cl3-P 2H 16000 292IiO __ 45250 16515 14-P__ __ 299 bull_____ 36900 36900 123Ujc19-P ____ 2 i3 17000 27337 44337 16421 c20-P _________ 2 M 16000 29025 45025 15315

1 TotaL __ _ -24 r 6Uo -zq712 ~~3937i 1 420600fl39ll

16 TECHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 7-Releasea of Trichogramma minutum in augarcane in Louiaiana-Con

ROUM- RELEASES 1935

Parasites released on dates speltled

Plot No Size of 1-------------shyplot

June 14 July 27 Aug 8 -ug Total

released Released per acre

13-14

---------1------------------------ACIt Number Number Number Number Number Number

21-P 22-P 23middotP 24-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull bullbullbullbullbullbull 25-P 26-Pbullbullbullbullbullbullbullbull 27P c30-P c31-P c32middotP

152 319 290 687 185 328 220 262 361 I ()Q

14250 Zl25O 29500 42500 14700 28125

27250 42000 40 AJO 4P300 ~OOO 37000 SO750

21000 45000 tqOOO 42000 41500 83500

48000 57500 bullbullbullbullbullbullbullbull 77100 47600

62500 lIO25O 107500 130800 74200

14R625 98750 57500 77100 47600

41118 34561 37069 19039 40108 45312 H88fl 21947 21357 43670

c33-P 135 3~ 000 bullbullbullbullbullbullbullbull 34 000 25184

Totel 3048 152325 261300 216200 319000 94B825 31111

In 1935 parasites were released at rates of from 10000 to 45000 per acre In the Jeanerette area an average of approximately 14000 Trichogramma were released per acre but in the Houma area the avershyage number per acre was about 31000 The dates and approximate rates of releases made in 1935 are also shown in table 7

Herbert Spencer of the Division of Fruit Insect Investigations of the Bureau of Entomology and Plant Quarantine kindly supplied from Albany Ga all the Trichogramma used in these experiments excepting those supplied by the Louisiana Agricultural Experiment Station for release in cooperative experiments These parasites were all of the dark Louisiana strain being progeny of adults obtained from eggs of Diatraea saccharalis collected in Louisiana

Parasites were requested as needed and disks of cardboard containshying approximately 50000 Sitotroga eggs that had been exposed to parasites were sent usually just after the eggs had turned black A count was made on each card at 2 or more points to obtain the percentshyage of parasitization The cards were cut in halves quarters or thirds as desired and were placed in petri dishes for emergence The day after the parasites began to emerge a sufficiently large number usually had emerged and mated to justify their release The dishes of parasites were protected from the sun and heat while being transported to fields for release It was sometimes necessary to use ice in keeping them cool In the latter case the Trichogramma adults became active a few minutes after the container was placed in the open air

Care was taken to get as even a distribution of the parasites in the field as possible The method used was to open a dish slightly and allow the parasites to escape while the operator was walkin between rows of cane From one to three complete rounds were made in each colonized plot in releasing the parasites The cards containing the parasitized eggs were often retained for another day or two in the dishes after the initial release to allow any parasites that had not emerged to emerge and matr before bein released If however pracshytically all the parasites had emerged the cards were torn into small pieces and placed on various cftne stalks

EXPERUIENTS FOR CONmOL OF SUGAROANE BORER 17

RATE OF PARASITIZATION

Examinations for borer egg clusters were begun in April each year Additional examinations wera made at intervals of 2 or 3 weeks thereshyafter until the middle or end of September A record was kept of all egg clusters collected In 1933 the percentage of parasitization was based only on eggs from which neither borers had hatched nor parashysites had emerged In 1934 and 1935 the percentage of parasitization was obtained on eggs from which borers had hatched or parasites had emer~ed as well as on eggs from which neither borers had hatched nor parasites had emerged The parasitization was usually higher in the unhatched clusters However the rate of parasitization between colonized buffer and check plots ran in approlmately the same proportion for both groups This can be seen in tables 9 and 10

TABLE 8-Data on the parasitization of eggs of the sugarcane borer by Trichogramma minutum Louisiana 1988

EXPERIMENTS IN SUGARCANE

I Colonized areas Buffer areas 1 Check areas

Date examined Total I~B~Sit

II

Total ~a~it1 Total 1 ~a~itmiddot I eggs IzatlOn I eggs Izatlon eggs IZ8t10n

-Ap-r-----24--bull-bullbull---bullbull-bullbull-bull--bullbull-bull-bullbull----bullbull-bullbull--bullrN-um-2-b~-~ t Perc~~~ ~ Numb3~ Perc~~~ INumf~ IPtTCt~~ 0

May 1-15bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __ 0 I -0 Imiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot bullbull- bullbull 57 0 May 19-Jlwe L bullbullbullbullbullbullbull_ 51 0 _bullbull 1 44 0 June 5-16bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 1 1038 33 U5 0 66 0 June 26-1uly 5 428 14 __ _ bullbull __ 202 31 July 10-13 bullbull 138 l 0 164 134 lui) 18-29bull _bullbull _bullbullbullbullbullbullbullbullbull _ 766 t 18 - bullbullbullbullbull _ 541 52 July 31-Aug 17bullbullbull __ bull_bullbullbullbullbullbull_bullbullbullbull _ 17s- 171 189 101 1727 219 Aug I8-Sept 8bullbullbullbullbullbull -bullbullbullbullbullbull _1 112741 695 699 961 7032 677 ScPt12-25bullbullbullbullbull _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull j 19149 864 2355 923 13598 876 Sept 26-28bullbullbullbull _bullbullbull _ 6211 903 1545 925 5037 867

EXPERIMENTS IN CORN

56 71 o 0

483 178 2i3 1000

1 Not all oC the buffer arrAS were examined when colonized and check Breas were examinerl

Usually 1 man-hour of search was made for borer egg clusters in each of the colonized buffer and check plots with the exception that early in the season when eggs were scarce and while a large number of plots were under comiideration sometimes only 30 minutes was spent in each plot At the time of collection the egg clusters were divided into four groups as follows (1) Parasitized clusters from whch no insects had emerged (2) parasitized clusters from which emergence had begun (3) unparasitized clusters in which no eggs had hatched and (4) unparasitized clusters in which some or all of the eggs had hatched The eggshells of the completely hatched or emerged clusters vmiddotere counted at the time of collection or later The parashysitized eggs of the unemerged clusters were counted immediately or placed in an ice box until counted The unhatched and apparently nonparasitized eggs were held for at least 4 days then examined or

+45990-41--3

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

16 TECHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 7-Releasea of Trichogramma minutum in augarcane in Louiaiana-Con

ROUM- RELEASES 1935

Parasites released on dates speltled

Plot No Size of 1-------------shyplot

June 14 July 27 Aug 8 -ug Total

released Released per acre

13-14

---------1------------------------ACIt Number Number Number Number Number Number

21-P 22-P 23middotP 24-Pbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull bullbullbullbullbullbull 25-P 26-Pbullbullbullbullbullbullbullbull 27P c30-P c31-P c32middotP

152 319 290 687 185 328 220 262 361 I ()Q

14250 Zl25O 29500 42500 14700 28125

27250 42000 40 AJO 4P300 ~OOO 37000 SO750

21000 45000 tqOOO 42000 41500 83500

48000 57500 bullbullbullbullbullbullbullbull 77100 47600

62500 lIO25O 107500 130800 74200

14R625 98750 57500 77100 47600

41118 34561 37069 19039 40108 45312 H88fl 21947 21357 43670

c33-P 135 3~ 000 bullbullbullbullbullbullbullbull 34 000 25184

Totel 3048 152325 261300 216200 319000 94B825 31111

In 1935 parasites were released at rates of from 10000 to 45000 per acre In the Jeanerette area an average of approximately 14000 Trichogramma were released per acre but in the Houma area the avershyage number per acre was about 31000 The dates and approximate rates of releases made in 1935 are also shown in table 7

Herbert Spencer of the Division of Fruit Insect Investigations of the Bureau of Entomology and Plant Quarantine kindly supplied from Albany Ga all the Trichogramma used in these experiments excepting those supplied by the Louisiana Agricultural Experiment Station for release in cooperative experiments These parasites were all of the dark Louisiana strain being progeny of adults obtained from eggs of Diatraea saccharalis collected in Louisiana

Parasites were requested as needed and disks of cardboard containshying approximately 50000 Sitotroga eggs that had been exposed to parasites were sent usually just after the eggs had turned black A count was made on each card at 2 or more points to obtain the percentshyage of parasitization The cards were cut in halves quarters or thirds as desired and were placed in petri dishes for emergence The day after the parasites began to emerge a sufficiently large number usually had emerged and mated to justify their release The dishes of parasites were protected from the sun and heat while being transported to fields for release It was sometimes necessary to use ice in keeping them cool In the latter case the Trichogramma adults became active a few minutes after the container was placed in the open air

Care was taken to get as even a distribution of the parasites in the field as possible The method used was to open a dish slightly and allow the parasites to escape while the operator was walkin between rows of cane From one to three complete rounds were made in each colonized plot in releasing the parasites The cards containing the parasitized eggs were often retained for another day or two in the dishes after the initial release to allow any parasites that had not emerged to emerge and matr before bein released If however pracshytically all the parasites had emerged the cards were torn into small pieces and placed on various cftne stalks

EXPERUIENTS FOR CONmOL OF SUGAROANE BORER 17

RATE OF PARASITIZATION

Examinations for borer egg clusters were begun in April each year Additional examinations wera made at intervals of 2 or 3 weeks thereshyafter until the middle or end of September A record was kept of all egg clusters collected In 1933 the percentage of parasitization was based only on eggs from which neither borers had hatched nor parashysites had emerged In 1934 and 1935 the percentage of parasitization was obtained on eggs from which borers had hatched or parasites had emer~ed as well as on eggs from which neither borers had hatched nor parasites had emerged The parasitization was usually higher in the unhatched clusters However the rate of parasitization between colonized buffer and check plots ran in approlmately the same proportion for both groups This can be seen in tables 9 and 10

TABLE 8-Data on the parasitization of eggs of the sugarcane borer by Trichogramma minutum Louisiana 1988

EXPERIMENTS IN SUGARCANE

I Colonized areas Buffer areas 1 Check areas

Date examined Total I~B~Sit

II

Total ~a~it1 Total 1 ~a~itmiddot I eggs IzatlOn I eggs Izatlon eggs IZ8t10n

-Ap-r-----24--bull-bullbull---bullbull-bullbull-bull--bullbull-bull-bullbull----bullbull-bullbull--bullrN-um-2-b~-~ t Perc~~~ ~ Numb3~ Perc~~~ INumf~ IPtTCt~~ 0

May 1-15bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __ 0 I -0 Imiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot bullbull- bullbull 57 0 May 19-Jlwe L bullbullbullbullbullbullbull_ 51 0 _bullbull 1 44 0 June 5-16bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 1 1038 33 U5 0 66 0 June 26-1uly 5 428 14 __ _ bullbull __ 202 31 July 10-13 bullbull 138 l 0 164 134 lui) 18-29bull _bullbull _bullbullbullbullbullbullbullbullbull _ 766 t 18 - bullbullbullbullbull _ 541 52 July 31-Aug 17bullbullbull __ bull_bullbullbullbullbullbull_bullbullbullbull _ 17s- 171 189 101 1727 219 Aug I8-Sept 8bullbullbullbullbullbull -bullbullbullbullbullbull _1 112741 695 699 961 7032 677 ScPt12-25bullbullbullbullbull _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull j 19149 864 2355 923 13598 876 Sept 26-28bullbullbullbull _bullbullbull _ 6211 903 1545 925 5037 867

EXPERIMENTS IN CORN

56 71 o 0

483 178 2i3 1000

1 Not all oC the buffer arrAS were examined when colonized and check Breas were examinerl

Usually 1 man-hour of search was made for borer egg clusters in each of the colonized buffer and check plots with the exception that early in the season when eggs were scarce and while a large number of plots were under comiideration sometimes only 30 minutes was spent in each plot At the time of collection the egg clusters were divided into four groups as follows (1) Parasitized clusters from whch no insects had emerged (2) parasitized clusters from which emergence had begun (3) unparasitized clusters in which no eggs had hatched and (4) unparasitized clusters in which some or all of the eggs had hatched The eggshells of the completely hatched or emerged clusters vmiddotere counted at the time of collection or later The parashysitized eggs of the unemerged clusters were counted immediately or placed in an ice box until counted The unhatched and apparently nonparasitized eggs were held for at least 4 days then examined or

+45990-41--3

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

EXPERUIENTS FOR CONmOL OF SUGAROANE BORER 17

RATE OF PARASITIZATION

Examinations for borer egg clusters were begun in April each year Additional examinations wera made at intervals of 2 or 3 weeks thereshyafter until the middle or end of September A record was kept of all egg clusters collected In 1933 the percentage of parasitization was based only on eggs from which neither borers had hatched nor parashysites had emerged In 1934 and 1935 the percentage of parasitization was obtained on eggs from which borers had hatched or parasites had emer~ed as well as on eggs from which neither borers had hatched nor parasites had emerged The parasitization was usually higher in the unhatched clusters However the rate of parasitization between colonized buffer and check plots ran in approlmately the same proportion for both groups This can be seen in tables 9 and 10

TABLE 8-Data on the parasitization of eggs of the sugarcane borer by Trichogramma minutum Louisiana 1988

EXPERIMENTS IN SUGARCANE

I Colonized areas Buffer areas 1 Check areas

Date examined Total I~B~Sit

II

Total ~a~it1 Total 1 ~a~itmiddot I eggs IzatlOn I eggs Izatlon eggs IZ8t10n

-Ap-r-----24--bull-bullbull---bullbull-bullbull-bull--bullbull-bull-bullbull----bullbull-bullbull--bullrN-um-2-b~-~ t Perc~~~ ~ Numb3~ Perc~~~ INumf~ IPtTCt~~ 0

May 1-15bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull __ 0 I -0 Imiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddotmiddot bullbull- bullbull 57 0 May 19-Jlwe L bullbullbullbullbullbullbull_ 51 0 _bullbull 1 44 0 June 5-16bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull 1 1038 33 U5 0 66 0 June 26-1uly 5 428 14 __ _ bullbull __ 202 31 July 10-13 bullbull 138 l 0 164 134 lui) 18-29bull _bullbull _bullbullbullbullbullbullbullbullbull _ 766 t 18 - bullbullbullbullbull _ 541 52 July 31-Aug 17bullbullbull __ bull_bullbullbullbullbullbull_bullbullbullbull _ 17s- 171 189 101 1727 219 Aug I8-Sept 8bullbullbullbullbullbull -bullbullbullbullbullbull _1 112741 695 699 961 7032 677 ScPt12-25bullbullbullbullbull _bullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbullbull j 19149 864 2355 923 13598 876 Sept 26-28bullbullbullbull _bullbullbull _ 6211 903 1545 925 5037 867

EXPERIMENTS IN CORN

56 71 o 0

483 178 2i3 1000

1 Not all oC the buffer arrAS were examined when colonized and check Breas were examinerl

Usually 1 man-hour of search was made for borer egg clusters in each of the colonized buffer and check plots with the exception that early in the season when eggs were scarce and while a large number of plots were under comiideration sometimes only 30 minutes was spent in each plot At the time of collection the egg clusters were divided into four groups as follows (1) Parasitized clusters from whch no insects had emerged (2) parasitized clusters from which emergence had begun (3) unparasitized clusters in which no eggs had hatched and (4) unparasitized clusters in which some or all of the eggs had hatched The eggshells of the completely hatched or emerged clusters vmiddotere counted at the time of collection or later The parashysitized eggs of the unemerged clusters were counted immediately or placed in an ice box until counted The unhatched and apparently nonparasitized eggs were held for at least 4 days then examined or

+45990-41--3

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

---------------

18 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

placed in the ice box to be counted later This allowed any eggs that might be parasitized to turn black and thus become evident before counting Separating the clusters from which no emergence of either parasite or borer larva had taken place at the time of collection preshyvented classifying them wrongly later as a number of these clusters would begin to produce parasites or borers before the final count could be made and the empty shells might be misclassified TABLE 9-Data on 10 ecperiments in releases of Trichogramma minutum against

the eggs of the sugarcane borer at Jeanerette and 10 at Houma La 1934

AT JEANERETTE LA

Unhatched artd unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates or examinations Ilnd piot treatments Para- Unpara- Para- Unpara-Para- Parashysitized sitized sitized sitizedsitization sitizationeggs eggs eggs eggs

June 18-28 Number Number PtTCtllt Ntlmber NutMu PercentColonized _________________ ___________ 0 474 00 0 738 00Buffer_____ bull__________ bull_______________ 0 310 0 0 4H 0Check _________ bull________ _ _________ 0 502 0 0 748 0 JulyColonized21-Aul 6 ____ bull__________ bull____ bull________ 398 1001 169 450 4497 91Builer________ bull___ bull _________ __ _ ___ 310 1442 177 418 3588 104Check ________________ bull__ bull_bullbull ________ 626 1122 358 798 3178 201 AultI5-17

Colonized_____ ___ ___ bull___ bull_______ 7073 1253 MO fi74O 4250 696BulIer____ ______________ bull __________ 7089 1136 862 10353 4130 715Check _________ bull_________________ bull___ 7292 1094 870 10103 4350 700 Sept 12-14Colonized_______________ bullbull ________ _ 7560 1289 854 16268 2987 845Buffer ________________________ 7003 1334 840 15 159 2807 844

Clieek ______ __________ 6873 I ~09 830 15810 2556 861

AT HOUMA LA

t

IJune 18-25COlonized _________ bullbullbull ____ __ I 6 450 13 I I 6 1128 OSButTerbullbull _________ _ ____ __ 0 15 0 0 426 0 Check __ _ __ _ ___ _ __ =- 18 41lO 38 18 718 24

July 20-26Colonized_______________ _ _ 195 399 32S 287 2 149 118 ButTer __ ___ _____ ____ _= == S1 275 228 96 Isns 40Check __ __________ ____ 1I9 326 267 150 2187 6A

AUI 10-16shy-Coloni~ed____________________ 2689 741 i84 3996 2934 577 ButTer _______________ 3215 8fli 788 4326 3381 561Check ____________________ 1763 691 718 3157 2729 536

Sept U-JiColonized_________ bull _ _ __ _____ 7442 387 951 16675 ~271 880 ButT~r _ ___________________ 8523 185 979 16906 1999 894 Ch~ek_ bullbull __________________________ 8691 179 980 18178 2203 892

The progress of parasitization in the borer egg clusters found throughout the three seasons is shown in table S for 1933 in table 9 for 1934 and in table 10 for 1935 It may be seen that in 1933 the rates of parasitization in the colonized and check plots of sugarcane were closely similar from the middle of July until the end of Sepshytember In 1934 at Jeanerette during the last of Tuly the parasitishyzntion in the checks averaged 201 percent while that in the plots to be used or which had already been used for colonization averaged 91 percent At Houma the colonized plots showed US percent parasitization to the 64 percent in the checks for collections made from Julv 20 to 26 In the September counts there was less than a 2-percent difference between the colonized buffer and check plots at both Jeanerette and Houma At this time little difference in the percentage of parasitization was expccted as the uncolonized plots

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

19 EXPERIMENTS FOR CONTROL OF SUGAlWANE BORER

had had a chance to catch up with the colonized plots In the collecshytions made during the middle of August however a much higher percentage of parasitization should have been evident in the colonized plots than in the check plots if nny benefit were derived from the releases In the Houma c--periments the colonized plots av(rage 577 percent parasitization compared with 536 pcrcent in the chccks or only 4 percent more and they already had a lead of 5 perccnt over the checks in July In the Jeanerette experiments in August the check the colonized and the buffer plots had practically the same percentage of parasitization Although they were even in August the colonized plots had actually gained more in parasitization since the end of July as the checks at that time had exceeded the colonized plots in the rate of parasitization by 11 percent

TABLE 1O-Dala 01 9 experiments -in releases of TrichograTmna 111pound111111111 against the eggs of the sugarcamiddottIe borer at Jeanerette La awlll at Howlla La 1985

AT JEANERETTF LA

Unhatched and unemerged Hatched unhatched emerged eggs and unemerged eggs

Dates of examinations and plot treatments I I ~Ira i Upara Para ~ara Uparamiddot Para sltlzed I sltl1ed 1 sitization SltiZed slUzed sitlzation

eggs I eggs I eggs eggs-----__-----_-------------------June 5-11 NLllwer f Number Percrnt Numf)er Number Perctn

Colonized ~ 0 137 00 0 161 00 Buffer ~~ 12 150 74 12 245 7 Check 0 96 0 0 172 0

June 15-27 Colonized ~ 66 5U 112 69 1238 53 Buffer middot1 103 1 266 279 118 616 101

JUly~~~~ 59 398 129 59 678 80

COlonized 96 224 300 193 i t223 136 Buffer bull 65 21 73 II 156 563 217 Check 54 73 425 153 634 194

July 2amp-Aug 12 Colonized 346 66- 342 3991 1454 21~ Buffer ~ ~ 30 66- 31 4 428 1382 236 Check ~ 287 3591 444 368 i 887 293

Aug 2(28 I

Colonized I 714 ~0349 943 3004 1459 712 Buffer ~~I 1235 832 3259middot 1433 695 Check 1612 238 i $7 1 3581 1653 684

Sept 17-23 I I Colonized 2346 806 I 744 5273 I 1366 794

789~~~~=middotl ~~ 1 ~~ I ~g ~~ i tlli 802

AT HOU~IA LA

June 4-14 Colonized Duffer

487 81

t2 229

)3d 1144

lUi 01

157 Check 251 70 19 369 4-11

June 17-21 f Colonited

~g~~ 1 July 15-31 I

COlonized ~

~~~tmiddotmiddot1 Aug 1f 23 i

~~8~~~ 1 Check ~

Septbullbull~2 Colonized Buffer Check

3ii 2G1J 266

209 226 2lmiddot1

88 0

deg1 53 [ 94 I

122

53ij 572 764

9349171923

Ii 0 1 0

I 40

~ I 711 1 651

1 114 1 6212 57H 1 56il6

I

6J6 74

1i8

659 622 71)5

177t 1630 2294

2 311 221lS 1910

25 0 0

57 Ii 5 1gt4

287 285 32 7

727 716 749

20 TECHNICL BULLE-T1N 743 U S DEPr OFAGlUCULTURE

In comparing the parasitization in borer egg clusters collected during 1935 in both the Jeanerette and Houma areas it may be seen that the rates of parasitization between the colonized buffer and check plots were closely similar throughout the season especially after the first of July Similarly in comparing the progress of parashysitization of the borer egg clusters found throughout the three seasons very little difference was noticed between the colonized buffer and check plots (figs 2 and 3)

00 -shy95

90 I --shy85 I 80

I ~ 75

~ 10 I

N

j 65

~ 60 a ~ 55

SO

I I I I

0 45 I ~ 40 ~ Z 35 --COLONIZED ~ IIJ

~ 30 --8UfFER -----CHECK

~ 25

20

15

10

5 ---------shy) ---JUNE JUNE 2ampshy JUIY JUIV 31- AUG 18- SEPT SEPT 5-16 JULY 5 18-29 AUG 17 SEPT 8 12-25 26-28

1933

FIGURE 2-Average percentages of parasitization in the colouized buffer and check plots in sugarcane in experiments on the control of the sugarcane borer by TrichoflTamma minlltum Louisiana 1933

During 1933 77972 eggs wen~ examined to obtain the percentage of parasitization These did not include the parasitized eggs from which the parusites had emerged or the hatched nonparasitized eggs In 1934 221119 eggs were examined including both emerged and unemerged parasitized eggs and the hatched and unhatched nonshyparasitized eggs In 1935 94766 eggs were examined for parasitism including emerged and unemerged borer eggs Fewer eggs were examined in 1935 than in 1934 more because examinations were made at greater intervals than because of any reduction in the borer infestashytion Data on the collection find examination of borer eggs are given in detail in table 11 for experiments cZ in 1934 and c20 in 1935 This table shows the progress of parasitization in representative plotWthe cooperative experiments

21 EXPERIlIENTS FOR CONTROL OF SUGARCANE BOUER

80 80

f 85 ~15 15

10 shy10

65 65 r

~~ 60

50

45

~ ~F -- COl-OHIZtO

--COLONIZED --BUFFER --BUFFER _- - CHECK bull bull CHECIlt

~ ~f15r lOr sr A

JULY JULY 21- AUG SEPT AUG 10-20 AUG 6 S-17 12-14 26-29

--COLONIZED --SUFFER -- middot--CHECIlt

FIGURE 3-middotAverage percentage of parasitization in the colonized buffer and check plots in sugarcane in experiments on the control of the sugtrcane borer by lhchogramma mi111ltum in experiments at A Jeanerette La in 193413 Houma La in 1934 C Jeanerette in 1935 D Houma in 1935

22 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE n-Progress of parasitization i1l representatille plots oj the cooperative experiments i1l mass releases of Trichogramma millutum for the control of the sugarcale borer in Louisiana 1934 and 1935

rrOUMA EXPERIMENT c2 1931

I Condition of eggs in-

Time -----C-o-JO-n-iz-e-d-p-Io-t---~----B-u-ffe-r-p-~-t----~------C-h-~-k-P-JO-t----shyspentDateof in --------------middot1--------------1---------------shy

exnmtna~

tion exammiddot Hatched Hntched I Hatched

~i~~ Un~~dhed i u~~~~~~d un~~tted u~~~~~~I Un~ted IU~~~~d unemerged I and unemerged and unemerged and

unemerged IJnemerged unemerged -------i----middot--~~-I----~---middotI---~---I---~middot--I---~---l---~--shy

_fin-I Nllmj Per- INumI Permiddot Nummiddot1 Permiddot Num- plt[ Nmnmiddot1 Per- Nummiddot Permiddot ul btr cont I btT cent btT ctnt ber cwt btT 1 ctonto berO CtOl1tO

Apr 17 30 27 00 I 27 00 0 00 0 00 o l[ay 17 30 0 0 0 10 0 0 0 n 0 0 0 0June 4 30 20 0 I 20 0 31 0 3~ 0 69 0 fq 0 June 12 30

1 0 1 29 0 10 0 31 0 0 32 029 32

June IlL JuJr 9 ~g 1~ 100g I I~ Sg 5g g 2~ g li~ g iri~ 8 July 20 10 19 1000 I 193 98 0 0 0 0 0 0 0 0 July 26 30 I US 60 I 397 23 19 0 I 141 0 39 0 230 0 Aug14 bull 60 Hi~ 853 1 1000 769 ~71 67S 891 454 303 676 i58 558 Sept 12 60 1101 95911976 921 996 1000 2331 8i ~ 803 96 I 1672 SO I o~t 5 20 l 359 912 I liS7 898 211 SO3 I 602 860 141 823 4Q8 91 4

~-~-~-~-~---

JEANERETTE EXPERIgtlENI c~O 1935

June liyenoJ 129 202 I 211 113 I 1~91 29l I 251 I 271 I 132 26j r---IJuly 6 bull 2S 1000 12fi 312 I v) I (gt821 223 320 I 14middot 1000 I 180 394 July Z7~~~r 66 91 I 2~4 23 176 112 II 301 lG 32 28I 140 293 AUI2S_ I 420

j

962 81 74 1 1 21H I 759 997 i 69 I 3G4 I 1000 1017 6K R Sepl 18 235 91 9 I

j

646 923 1 149 I 92 fl seo Si 1~53 I 111 0 L~ 907 j

BORER-INFESTATION COUNTS

In the fall of ench yelH borer-inf(station counts wen madc and the percentage of joints borN was cncI1111t(d An average of 150 stnlks were examined from eneh of tll( 3 plots in 1933 but in 1934 and 1935 200 stalks were examined from euch of the 3 plots The total number of joints and till joints bored externally were recorded for each stnlk Holes made by t1l( borer larvae for the exit of the moth were recorded in 1934 and 1935 but the data on exit holes wer( considenmiddotd qu(stionabl( as it was not always possible to distinguish between exit holes and other holes made by larg( larvae

The data from thes( experiments are giv(n in detail in table 12 with ench set of experiments summarized Itt th( end of each section of the table

-------------

-------- --

----------

(

(

EXPERlMENTS FOR CONTROL OF SUGARCANE 130RER 23 TAllLE 12-Experiments in the mass liberation of Trichogramma minutum 1nshy

jestatioY by the sugarcane borer in colonized buffer and check plot8 of 8ugarcane as judged b the number of 8talk8 and joint8 bored

HOUMA AND ~EANERETTE LA 1933

Stalks Joints Plot ExitVariety nnd (70P TrfatrnentNo holesTot~lexmiddot1 101111 etmiddotDored Doredumined smined

gtlumber Percent Numb Perrent Number 1 Colonited bullbull 105 91 4 1565 334 - --~-- 2 ButTerbullbullbullbullbullbullbull 101 923 1465 277 --- --- 3 Cbeckbullbullbullbullbullbullbull 105 933 1461 280 ~----- -shy4 COlonizedbullbull 150 860 2047 209 ------ shy5 DuUerbullbullbullbullbullbullbull 75 693 915 179 -- _-shy6 Cbeckbullbullbullbullbullbull 150 81 a 2209 186 ---_ _-shy7 BuUer bullbull i5 9S7 100 308

P O 1 234 first stubblebullbullbullbull S COlonizedbullbullbull 150 980 2185 32 0 ---- ---shy20 Colonized bullbullbull 150 793 2211 157 __---shy21 RuUerbullbullbullbullbullbull 45 62 2 681 73 --- -----shy22 Checkbullbullbullbullbullbull 150 733 2 113 137

113 Colonizedbullbullbull 150 993 2121 3~8 - - shy114 DuUerbullbullbullbullbullbull 150 94 0 2057 311

~-

-_ _-- shy115 Checkbullbullbullbullbullbullbull 150 9~0 2023 290

~- ---- shy100 Colonizedbullbullbull 150 1000 2 166 497P O J 234 plantbullbullbullbullbullbullbullbullbullbull ----- - -III Cheek bullbullbull 150 993 2112 4e2 --- -- -

9 Coloniled bull 150 1000 2020 442 --W ButTerbullbullbull 150 993 2054 387

~-- 11 Check 150 1000 2llO7 403

~

~P o bull -1 12 Coloniledbullbull 300 883 3932 291 -~ - ~-- 16 Checkbullbullbullbullbullbullbull 300 777 3741 182 --shy~

19 Colonizedbullbullbull 2fJIl 905 2 335 410 _- H Bufferbullbullbullbullbullbull 17 1000 1S~7 399 -_ -_ _-shy17 Check bullbullbullbull 200 990 2419 396 -- -_

106 Colonized 150P O J 213 first stubblebullbullbullbullbull 1000 IM4 M5 shy107 Check 150 973 1487 479 ~ -shylOS Colonileltl~ 110 993 1589 516 - _--shy127 Colonized 110 900 1611 333 IU Check 150 993 1892 ~S31=

P 01213 second stubblebullbull 124 Colonized bull ro 1000 552 580 bullbullbullbullbullbullbullbullbullbull 125 Cheek 50 98 n 5~ 4361 13 COlonized bullbull 3m 99 7 406i 45 R bullbullbullbullbullbullbullbullbullbull

PO J 213 second stubblebullbull H DutTerbullbullbullbull 25 1000 273 396 Ibullbullbullbullbullbullbullbullbullbull 15 Checkbullbullbullbullbullbull 350 946 4099 315 i bullbullbull H IColonizedbullbullbull 2355 954 29945 1 373 I

Total and averagebullbullbullbullbull 8 DulTerbullbullbullbullbullbull ampXl 926 10420 bull 312 12 Check 2 051 914 26150 I 311 bullbullbullbullbullbullbullbullbullbull

JEANERETTE LA 1934

P O J 213 first stubblebullbullbullbullbull

P O J 213 second stubblebullbull

1 O J 234 plnnL

I I Colonized bullbullbull I ButTerbullbullbullbullbull I iCheckbullbullbullbullbullbullbull

2 Cnlonizedbullbullbull 2 PutTer bullbullbull _ bullbull 2 i Check

3 1Colonizedbullbull 3 ButTerbullbullbullbullbullbullbull

2001 210 bull

~I 200 200 200

895 971 970

93S 871 720

870 925

I

2

132

12234 2 141

2 362 2 2tll I 2oltri

300-5 3121

26 OS 3223 3162

28M 2716

11529

2126 t 2088

28 39 31

31 27 10

49 51

3 Checkbullbullbullbullbullbullbull 200 955 3013 2150 laquo

Co 281 tlrstslllbble bullbullbullbullbullbullbull 4 4 4

Colonizedbullbullbull DutTerbullbullbullbullbullbullbull Check

200 200 200 1

915 895 790

2244 2006 2 117

2638 2490 18 J4

29 27 19

P O J 234 Plnntbullbullbullbullbullbullbullbullbullbull I

5 Colonizedbullbullbull 5 ButTerbullbullbullbullbullbull 5 1 Checkbullbullbullbullbullbullbull

1m 110 150

793 907 000

2049 2 IS8 2249

1800 I

~Ui 31 74 76

f

1

l

21 EXPERIlIENTS FOR CONTROL OF SUGARCANE BOUER

80 80

f 85 ~15 15

10 shy10

65 65 r

~~ 60

50

45

~ ~F -- COl-OHIZtO

--COLONIZED --BUFFER --BUFFER _- - CHECK bull bull CHECIlt

~ ~f15r lOr sr A

JULY JULY 21- AUG SEPT AUG 10-20 AUG 6 S-17 12-14 26-29

--COLONIZED --SUFFER -- middot--CHECIlt

FIGURE 3-middotAverage percentage of parasitization in the colonized buffer and check plots in sugarcane in experiments on the control of the sugtrcane borer by lhchogramma mi111ltum in experiments at A Jeanerette La in 193413 Houma La in 1934 C Jeanerette in 1935 D Houma in 1935

22 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE n-Progress of parasitization i1l representatille plots oj the cooperative experiments i1l mass releases of Trichogramma millutum for the control of the sugarcale borer in Louisiana 1934 and 1935

rrOUMA EXPERIMENT c2 1931

I Condition of eggs in-

Time -----C-o-JO-n-iz-e-d-p-Io-t---~----B-u-ffe-r-p-~-t----~------C-h-~-k-P-JO-t----shyspentDateof in --------------middot1--------------1---------------shy

exnmtna~

tion exammiddot Hatched Hntched I Hatched

~i~~ Un~~dhed i u~~~~~~d un~~tted u~~~~~~I Un~ted IU~~~~d unemerged I and unemerged and unemerged and

unemerged IJnemerged unemerged -------i----middot--~~-I----~---middotI---~---I---~middot--I---~---l---~--shy

_fin-I Nllmj Per- INumI Permiddot Nummiddot1 Permiddot Num- plt[ Nmnmiddot1 Per- Nummiddot Permiddot ul btr cont I btT cent btT ctnt ber cwt btT 1 ctonto berO CtOl1tO

Apr 17 30 27 00 I 27 00 0 00 0 00 o l[ay 17 30 0 0 0 10 0 0 0 n 0 0 0 0June 4 30 20 0 I 20 0 31 0 3~ 0 69 0 fq 0 June 12 30

1 0 1 29 0 10 0 31 0 0 32 029 32

June IlL JuJr 9 ~g 1~ 100g I I~ Sg 5g g 2~ g li~ g iri~ 8 July 20 10 19 1000 I 193 98 0 0 0 0 0 0 0 0 July 26 30 I US 60 I 397 23 19 0 I 141 0 39 0 230 0 Aug14 bull 60 Hi~ 853 1 1000 769 ~71 67S 891 454 303 676 i58 558 Sept 12 60 1101 95911976 921 996 1000 2331 8i ~ 803 96 I 1672 SO I o~t 5 20 l 359 912 I liS7 898 211 SO3 I 602 860 141 823 4Q8 91 4

~-~-~-~-~---

JEANERETTE EXPERIgtlENI c~O 1935

June liyenoJ 129 202 I 211 113 I 1~91 29l I 251 I 271 I 132 26j r---IJuly 6 bull 2S 1000 12fi 312 I v) I (gt821 223 320 I 14middot 1000 I 180 394 July Z7~~~r 66 91 I 2~4 23 176 112 II 301 lG 32 28I 140 293 AUI2S_ I 420

j

962 81 74 1 1 21H I 759 997 i 69 I 3G4 I 1000 1017 6K R Sepl 18 235 91 9 I

j

646 923 1 149 I 92 fl seo Si 1~53 I 111 0 L~ 907 j

BORER-INFESTATION COUNTS

In the fall of ench yelH borer-inf(station counts wen madc and the percentage of joints borN was cncI1111t(d An average of 150 stnlks were examined from eneh of tll( 3 plots in 1933 but in 1934 and 1935 200 stalks were examined from euch of the 3 plots The total number of joints and till joints bored externally were recorded for each stnlk Holes made by t1l( borer larvae for the exit of the moth were recorded in 1934 and 1935 but the data on exit holes wer( considenmiddotd qu(stionabl( as it was not always possible to distinguish between exit holes and other holes made by larg( larvae

The data from thes( experiments are giv(n in detail in table 12 with ench set of experiments summarized Itt th( end of each section of the table

-------------

-------- --

----------

(

(

EXPERlMENTS FOR CONTROL OF SUGARCANE 130RER 23 TAllLE 12-Experiments in the mass liberation of Trichogramma minutum 1nshy

jestatioY by the sugarcane borer in colonized buffer and check plot8 of 8ugarcane as judged b the number of 8talk8 and joint8 bored

HOUMA AND ~EANERETTE LA 1933

Stalks Joints Plot ExitVariety nnd (70P TrfatrnentNo holesTot~lexmiddot1 101111 etmiddotDored Doredumined smined

gtlumber Percent Numb Perrent Number 1 Colonited bullbull 105 91 4 1565 334 - --~-- 2 ButTerbullbullbullbullbullbullbull 101 923 1465 277 --- --- 3 Cbeckbullbullbullbullbullbullbull 105 933 1461 280 ~----- -shy4 COlonizedbullbull 150 860 2047 209 ------ shy5 DuUerbullbullbullbullbullbullbull 75 693 915 179 -- _-shy6 Cbeckbullbullbullbullbullbull 150 81 a 2209 186 ---_ _-shy7 BuUer bullbull i5 9S7 100 308

P O 1 234 first stubblebullbullbullbull S COlonizedbullbullbull 150 980 2185 32 0 ---- ---shy20 Colonized bullbullbull 150 793 2211 157 __---shy21 RuUerbullbullbullbullbullbull 45 62 2 681 73 --- -----shy22 Checkbullbullbullbullbullbull 150 733 2 113 137

113 Colonizedbullbullbull 150 993 2121 3~8 - - shy114 DuUerbullbullbullbullbullbull 150 94 0 2057 311

~-

-_ _-- shy115 Checkbullbullbullbullbullbullbull 150 9~0 2023 290

~- ---- shy100 Colonizedbullbullbull 150 1000 2 166 497P O J 234 plantbullbullbullbullbullbullbullbullbullbull ----- - -III Cheek bullbullbull 150 993 2112 4e2 --- -- -

9 Coloniled bull 150 1000 2020 442 --W ButTerbullbullbull 150 993 2054 387

~-- 11 Check 150 1000 2llO7 403

~

~P o bull -1 12 Coloniledbullbull 300 883 3932 291 -~ - ~-- 16 Checkbullbullbullbullbullbullbull 300 777 3741 182 --shy~

19 Colonizedbullbullbull 2fJIl 905 2 335 410 _- H Bufferbullbullbullbullbullbull 17 1000 1S~7 399 -_ -_ _-shy17 Check bullbullbullbull 200 990 2419 396 -- -_

106 Colonized 150P O J 213 first stubblebullbullbullbullbull 1000 IM4 M5 shy107 Check 150 973 1487 479 ~ -shylOS Colonileltl~ 110 993 1589 516 - _--shy127 Colonized 110 900 1611 333 IU Check 150 993 1892 ~S31=

P 01213 second stubblebullbull 124 Colonized bull ro 1000 552 580 bullbullbullbullbullbullbullbullbullbull 125 Cheek 50 98 n 5~ 4361 13 COlonized bullbull 3m 99 7 406i 45 R bullbullbullbullbullbullbullbullbullbull

PO J 213 second stubblebullbull H DutTerbullbullbullbull 25 1000 273 396 Ibullbullbullbullbullbullbullbullbullbull 15 Checkbullbullbullbullbullbull 350 946 4099 315 i bullbullbull H IColonizedbullbullbull 2355 954 29945 1 373 I

Total and averagebullbullbullbullbull 8 DulTerbullbullbullbullbullbull ampXl 926 10420 bull 312 12 Check 2 051 914 26150 I 311 bullbullbullbullbullbullbullbullbullbull

JEANERETTE LA 1934

P O J 213 first stubblebullbullbullbullbull

P O J 213 second stubblebullbull

1 O J 234 plnnL

I I Colonized bullbullbull I ButTerbullbullbullbullbull I iCheckbullbullbullbullbullbullbull

2 Cnlonizedbullbullbull 2 PutTer bullbullbull _ bullbull 2 i Check

3 1Colonizedbullbull 3 ButTerbullbullbullbullbullbullbull

2001 210 bull

~I 200 200 200

895 971 970

93S 871 720

870 925

I

2

132

12234 2 141

2 362 2 2tll I 2oltri

300-5 3121

26 OS 3223 3162

28M 2716

11529

2126 t 2088

28 39 31

31 27 10

49 51

3 Checkbullbullbullbullbullbullbull 200 955 3013 2150 laquo

Co 281 tlrstslllbble bullbullbullbullbullbullbull 4 4 4

Colonizedbullbullbull DutTerbullbullbullbullbullbullbull Check

200 200 200 1

915 895 790

2244 2006 2 117

2638 2490 18 J4

29 27 19

P O J 234 Plnntbullbullbullbullbullbullbullbullbullbull I

5 Colonizedbullbullbull 5 ButTerbullbullbullbullbullbull 5 1 Checkbullbullbullbullbullbullbull

1m 110 150

793 907 000

2049 2 IS8 2249

1800 I

~Ui 31 74 76

f

1

l

22 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE n-Progress of parasitization i1l representatille plots oj the cooperative experiments i1l mass releases of Trichogramma millutum for the control of the sugarcale borer in Louisiana 1934 and 1935

rrOUMA EXPERIMENT c2 1931

I Condition of eggs in-

Time -----C-o-JO-n-iz-e-d-p-Io-t---~----B-u-ffe-r-p-~-t----~------C-h-~-k-P-JO-t----shyspentDateof in --------------middot1--------------1---------------shy

exnmtna~

tion exammiddot Hatched Hntched I Hatched

~i~~ Un~~dhed i u~~~~~~d un~~tted u~~~~~~I Un~ted IU~~~~d unemerged I and unemerged and unemerged and

unemerged IJnemerged unemerged -------i----middot--~~-I----~---middotI---~---I---~middot--I---~---l---~--shy

_fin-I Nllmj Per- INumI Permiddot Nummiddot1 Permiddot Num- plt[ Nmnmiddot1 Per- Nummiddot Permiddot ul btr cont I btT cent btT ctnt ber cwt btT 1 ctonto berO CtOl1tO

Apr 17 30 27 00 I 27 00 0 00 0 00 o l[ay 17 30 0 0 0 10 0 0 0 n 0 0 0 0June 4 30 20 0 I 20 0 31 0 3~ 0 69 0 fq 0 June 12 30

1 0 1 29 0 10 0 31 0 0 32 029 32

June IlL JuJr 9 ~g 1~ 100g I I~ Sg 5g g 2~ g li~ g iri~ 8 July 20 10 19 1000 I 193 98 0 0 0 0 0 0 0 0 July 26 30 I US 60 I 397 23 19 0 I 141 0 39 0 230 0 Aug14 bull 60 Hi~ 853 1 1000 769 ~71 67S 891 454 303 676 i58 558 Sept 12 60 1101 95911976 921 996 1000 2331 8i ~ 803 96 I 1672 SO I o~t 5 20 l 359 912 I liS7 898 211 SO3 I 602 860 141 823 4Q8 91 4

~-~-~-~-~---

JEANERETTE EXPERIgtlENI c~O 1935

June liyenoJ 129 202 I 211 113 I 1~91 29l I 251 I 271 I 132 26j r---IJuly 6 bull 2S 1000 12fi 312 I v) I (gt821 223 320 I 14middot 1000 I 180 394 July Z7~~~r 66 91 I 2~4 23 176 112 II 301 lG 32 28I 140 293 AUI2S_ I 420

j

962 81 74 1 1 21H I 759 997 i 69 I 3G4 I 1000 1017 6K R Sepl 18 235 91 9 I

j

646 923 1 149 I 92 fl seo Si 1~53 I 111 0 L~ 907 j

BORER-INFESTATION COUNTS

In the fall of ench yelH borer-inf(station counts wen madc and the percentage of joints borN was cncI1111t(d An average of 150 stnlks were examined from eneh of tll( 3 plots in 1933 but in 1934 and 1935 200 stalks were examined from euch of the 3 plots The total number of joints and till joints bored externally were recorded for each stnlk Holes made by t1l( borer larvae for the exit of the moth were recorded in 1934 and 1935 but the data on exit holes wer( considenmiddotd qu(stionabl( as it was not always possible to distinguish between exit holes and other holes made by larg( larvae

The data from thes( experiments are giv(n in detail in table 12 with ench set of experiments summarized Itt th( end of each section of the table

-------------

-------- --

----------

(

(

EXPERlMENTS FOR CONTROL OF SUGARCANE 130RER 23 TAllLE 12-Experiments in the mass liberation of Trichogramma minutum 1nshy

jestatioY by the sugarcane borer in colonized buffer and check plot8 of 8ugarcane as judged b the number of 8talk8 and joint8 bored

HOUMA AND ~EANERETTE LA 1933

Stalks Joints Plot ExitVariety nnd (70P TrfatrnentNo holesTot~lexmiddot1 101111 etmiddotDored Doredumined smined

gtlumber Percent Numb Perrent Number 1 Colonited bullbull 105 91 4 1565 334 - --~-- 2 ButTerbullbullbullbullbullbullbull 101 923 1465 277 --- --- 3 Cbeckbullbullbullbullbullbullbull 105 933 1461 280 ~----- -shy4 COlonizedbullbull 150 860 2047 209 ------ shy5 DuUerbullbullbullbullbullbullbull 75 693 915 179 -- _-shy6 Cbeckbullbullbullbullbullbull 150 81 a 2209 186 ---_ _-shy7 BuUer bullbull i5 9S7 100 308

P O 1 234 first stubblebullbullbullbull S COlonizedbullbullbull 150 980 2185 32 0 ---- ---shy20 Colonized bullbullbull 150 793 2211 157 __---shy21 RuUerbullbullbullbullbullbull 45 62 2 681 73 --- -----shy22 Checkbullbullbullbullbullbull 150 733 2 113 137

113 Colonizedbullbullbull 150 993 2121 3~8 - - shy114 DuUerbullbullbullbullbullbull 150 94 0 2057 311

~-

-_ _-- shy115 Checkbullbullbullbullbullbullbull 150 9~0 2023 290

~- ---- shy100 Colonizedbullbullbull 150 1000 2 166 497P O J 234 plantbullbullbullbullbullbullbullbullbullbull ----- - -III Cheek bullbullbull 150 993 2112 4e2 --- -- -

9 Coloniled bull 150 1000 2020 442 --W ButTerbullbullbull 150 993 2054 387

~-- 11 Check 150 1000 2llO7 403

~

~P o bull -1 12 Coloniledbullbull 300 883 3932 291 -~ - ~-- 16 Checkbullbullbullbullbullbullbull 300 777 3741 182 --shy~

19 Colonizedbullbullbull 2fJIl 905 2 335 410 _- H Bufferbullbullbullbullbullbull 17 1000 1S~7 399 -_ -_ _-shy17 Check bullbullbullbull 200 990 2419 396 -- -_

106 Colonized 150P O J 213 first stubblebullbullbullbullbull 1000 IM4 M5 shy107 Check 150 973 1487 479 ~ -shylOS Colonileltl~ 110 993 1589 516 - _--shy127 Colonized 110 900 1611 333 IU Check 150 993 1892 ~S31=

P 01213 second stubblebullbull 124 Colonized bull ro 1000 552 580 bullbullbullbullbullbullbullbullbullbull 125 Cheek 50 98 n 5~ 4361 13 COlonized bullbull 3m 99 7 406i 45 R bullbullbullbullbullbullbullbullbullbull

PO J 213 second stubblebullbull H DutTerbullbullbullbull 25 1000 273 396 Ibullbullbullbullbullbullbullbullbullbull 15 Checkbullbullbullbullbullbull 350 946 4099 315 i bullbullbull H IColonizedbullbullbull 2355 954 29945 1 373 I

Total and averagebullbullbullbullbull 8 DulTerbullbullbullbullbullbull ampXl 926 10420 bull 312 12 Check 2 051 914 26150 I 311 bullbullbullbullbullbullbullbullbullbull

JEANERETTE LA 1934

P O J 213 first stubblebullbullbullbullbull

P O J 213 second stubblebullbull

1 O J 234 plnnL

I I Colonized bullbullbull I ButTerbullbullbullbullbull I iCheckbullbullbullbullbullbullbull

2 Cnlonizedbullbullbull 2 PutTer bullbullbull _ bullbull 2 i Check

3 1Colonizedbullbull 3 ButTerbullbullbullbullbullbullbull

2001 210 bull

~I 200 200 200

895 971 970

93S 871 720

870 925

I

2

132

12234 2 141

2 362 2 2tll I 2oltri

300-5 3121

26 OS 3223 3162

28M 2716

11529

2126 t 2088

28 39 31

31 27 10

49 51

3 Checkbullbullbullbullbullbullbull 200 955 3013 2150 laquo

Co 281 tlrstslllbble bullbullbullbullbullbullbull 4 4 4

Colonizedbullbullbull DutTerbullbullbullbullbullbullbull Check

200 200 200 1

915 895 790

2244 2006 2 117

2638 2490 18 J4

29 27 19

P O J 234 Plnntbullbullbullbullbullbullbullbullbullbull I

5 Colonizedbullbullbull 5 ButTerbullbullbullbullbullbull 5 1 Checkbullbullbullbullbullbullbull

1m 110 150

793 907 000

2049 2 IS8 2249

1800 I

~Ui 31 74 76

f

1

l

-------------

-------- --

----------

(

(

EXPERlMENTS FOR CONTROL OF SUGARCANE 130RER 23 TAllLE 12-Experiments in the mass liberation of Trichogramma minutum 1nshy

jestatioY by the sugarcane borer in colonized buffer and check plot8 of 8ugarcane as judged b the number of 8talk8 and joint8 bored

HOUMA AND ~EANERETTE LA 1933

Stalks Joints Plot ExitVariety nnd (70P TrfatrnentNo holesTot~lexmiddot1 101111 etmiddotDored Doredumined smined

gtlumber Percent Numb Perrent Number 1 Colonited bullbull 105 91 4 1565 334 - --~-- 2 ButTerbullbullbullbullbullbullbull 101 923 1465 277 --- --- 3 Cbeckbullbullbullbullbullbullbull 105 933 1461 280 ~----- -shy4 COlonizedbullbull 150 860 2047 209 ------ shy5 DuUerbullbullbullbullbullbullbull 75 693 915 179 -- _-shy6 Cbeckbullbullbullbullbullbull 150 81 a 2209 186 ---_ _-shy7 BuUer bullbull i5 9S7 100 308

P O 1 234 first stubblebullbullbullbull S COlonizedbullbullbull 150 980 2185 32 0 ---- ---shy20 Colonized bullbullbull 150 793 2211 157 __---shy21 RuUerbullbullbullbullbullbull 45 62 2 681 73 --- -----shy22 Checkbullbullbullbullbullbull 150 733 2 113 137

113 Colonizedbullbullbull 150 993 2121 3~8 - - shy114 DuUerbullbullbullbullbullbull 150 94 0 2057 311

~-

-_ _-- shy115 Checkbullbullbullbullbullbullbull 150 9~0 2023 290

~- ---- shy100 Colonizedbullbullbull 150 1000 2 166 497P O J 234 plantbullbullbullbullbullbullbullbullbullbull ----- - -III Cheek bullbullbull 150 993 2112 4e2 --- -- -

9 Coloniled bull 150 1000 2020 442 --W ButTerbullbullbull 150 993 2054 387

~-- 11 Check 150 1000 2llO7 403

~

~P o bull -1 12 Coloniledbullbull 300 883 3932 291 -~ - ~-- 16 Checkbullbullbullbullbullbullbull 300 777 3741 182 --shy~

19 Colonizedbullbullbull 2fJIl 905 2 335 410 _- H Bufferbullbullbullbullbullbull 17 1000 1S~7 399 -_ -_ _-shy17 Check bullbullbullbull 200 990 2419 396 -- -_

106 Colonized 150P O J 213 first stubblebullbullbullbullbull 1000 IM4 M5 shy107 Check 150 973 1487 479 ~ -shylOS Colonileltl~ 110 993 1589 516 - _--shy127 Colonized 110 900 1611 333 IU Check 150 993 1892 ~S31=

P 01213 second stubblebullbull 124 Colonized bull ro 1000 552 580 bullbullbullbullbullbullbullbullbullbull 125 Cheek 50 98 n 5~ 4361 13 COlonized bullbull 3m 99 7 406i 45 R bullbullbullbullbullbullbullbullbullbull

PO J 213 second stubblebullbull H DutTerbullbullbullbull 25 1000 273 396 Ibullbullbullbullbullbullbullbullbullbull 15 Checkbullbullbullbullbullbull 350 946 4099 315 i bullbullbull H IColonizedbullbullbull 2355 954 29945 1 373 I

Total and averagebullbullbullbullbull 8 DulTerbullbullbullbullbullbull ampXl 926 10420 bull 312 12 Check 2 051 914 26150 I 311 bullbullbullbullbullbullbullbullbullbull

JEANERETTE LA 1934

P O J 213 first stubblebullbullbullbullbull

P O J 213 second stubblebullbull

1 O J 234 plnnL

I I Colonized bullbullbull I ButTerbullbullbullbullbull I iCheckbullbullbullbullbullbullbull

2 Cnlonizedbullbullbull 2 PutTer bullbullbull _ bullbull 2 i Check

3 1Colonizedbullbull 3 ButTerbullbullbullbullbullbullbull

2001 210 bull

~I 200 200 200

895 971 970

93S 871 720

870 925

I

2

132

12234 2 141

2 362 2 2tll I 2oltri

300-5 3121

26 OS 3223 3162

28M 2716

11529

2126 t 2088

28 39 31

31 27 10

49 51

3 Checkbullbullbullbullbullbullbull 200 955 3013 2150 laquo

Co 281 tlrstslllbble bullbullbullbullbullbullbull 4 4 4

Colonizedbullbullbull DutTerbullbullbullbullbullbullbull Check

200 200 200 1

915 895 790

2244 2006 2 117

2638 2490 18 J4

29 27 19

P O J 234 Plnntbullbullbullbullbullbullbullbullbullbull I

5 Colonizedbullbullbull 5 ButTerbullbullbullbullbullbull 5 1 Checkbullbullbullbullbullbullbull

1m 110 150

793 907 000

2049 2 IS8 2249

1800 I

~Ui 31 74 76

f

1

l

24 TEOHNIOAL BULLETIN 743 U S DEPT OF AOlUOULTUlUoJ

TABliE 12-Experiments in the mass liberation of Trichogmmma minutum Inshyfestation by the sugarcane borer in colonized buffer and check plots of sugarcane as Judged by the number of stalks and j(ints bored-Continued

JEANERETIE LA lU33-Contlnucd

Stdks Joints

Vurlety and crop ~g~ lrenllllcnt -1-------- ~-middot-llo-re~l- ~oi~I __________I____I_____I_I1_II1_I_n6__1 i llore~ ~1~IIUC~ ______

Namalmiddot P-rcwt Number Ptrcent Numbtr o Colonized ou 00 0 5(~1 2922 IS

Co 290 plnnt 6 Dntrer 50 72 () 477 1614 I 6 Check 20050 lOS 0 464 2888 12

7 Colonized 900 2342 3497 till 7 DUller 200 970 2398 3766 91

Co ~ bullbull 7 Check 200 I 090 2415 4054 80

711 Colonized 51laquo)) ~Omiddot 00 4504~_ I 43 674 II~ 7n~ Bntrer bull 38 8 v

U1 ~I~~~~~ ~ ~ 1 O J 21 flrststubblo 8 BuIJeL 21M) 930 26l5 2831 88

8 Check 200 I 876 27OS 2000 76

J 9 Colonized 21M) 855 29middot15 1732 25 P G J 21-1 plllnt __ l U lInlIer 200 830 2058 16 00 ~O

9 Check_bullbullbullbullbull 21M) I 8305 2983 I 1600 29

JO I Colonized ~OO 1000 I 2707 M85 219 1 O J 234 plllnt 10 BntTer 200 000 2818 4030 201 10 I Chemiddotk 2110 I 000 27middot11 middot1732 1 198

COIOni1Cd bullbullbull -Isro ----oo43imiddot~---sw---7iimiddotolnLnmllwerage 1 BlllIer__ 1870 I 9170 I 23740 2791 I 06-

Checkbullbullbullbullbull __ J850 i 00 11 ~ 23406 I 2733 595

--------------------------HOUMA IA 103-

-------------~---~--~----~--~---3021 j

(0281 PI8Dt i cl Colonized cl I Buller cl Check

210 i 210 1 21O

895 87 (I sa 8

272middot 2 t8i 2816

27 00 I

2041 I

1 37 25

P O J 234 nrststubblC c2 c2 c2

Colonized Burrer Check1

~()(l 210 2001

1000 IOI)Q 005

2800 a175 3167

3916 13 1) I3o47l

70 52 32

P O J 213 nrslstubble 3 3 3

Colonized _ I Buller Check

200 I 210 200

000 000 005

2 428 27-17 2610

3682 29 ZI I 2751

57 31 36

P O J 2i~ seL-ondstubblcbullbull 4 4 4

Colonized Burrer Check

200 210 200

005 981 985

2llS1 2152 2114

4386 301)6 31SOt

78 45 30

5 Colonized 2IMl 785 26711 18 75 t 38 1 OJ 234 nrSLSIUbbIC 5 _ Burrer bullbullbull bull

5 Check 210 2IJO

8middot18 715

2 752 2573

(900 t 136-1

2~ 15

I I

P O J 213 first stubblebullbull__ I 1

6 6 I

7 7 7

8 8 8

9 I 9

ColoDized Jlurrer Check

Colonized I Bu11er C1llckoo bull

ColonIzed lluJer Checkbullbullbullbullbullbullbull i Colonizedbull Bu11er l Check

t~)21W) 21M)

200 200 200

~l ~ 2110

2IM1 200 ()(

010 970 745

980 980 tHO

980 000 975

000 955 070

2414 2629 2600

2368 2367 2300

205462481 2 5J9

2480 2439 2~

2576 1 27( I

14241

3131 I 30 0 2900 j

i

ro~2 2569

3222 2714 ~80 i

054 71 Z

48 7 39

of-I 38 18

20 34 )-

EXPERIMENTS lWR CONTROL OF SUGARCANE BOHI-lt 25

TABLE 12-Experime11Is in the mass liberatio of Trichogramma minutum Inmiddot fesation by Ihe sugarcane borer in colonized blljJer and check plols of sugarcae as judged b the number of stalks and joilts bored-Continued

HOUMA LA 1934-Continued

S tnlks J oiuLsI PlotVariety nnd crop rrentment I I I f xitNo

lotl exmiddot I Bored Ii To~1 exmiddot Dared i boles

-----~l-__I nmmed I___i____ I I Kumler I Fucwt IVumber IPercent Numbr

10 COlonizedbull 200 940 2 584 24 03 II 33

P O J 234 first stubble 10 Dutler_ 200 970 2740 2211 33 10 Cbeck_____ 200 920 2832 2048 t 39

I lcolonized1--OW --01821 25 197 1-aI071----roI Total and average --f Butler_____ 1 2050 95551 26169 I 274S 405

Check__ __ 2010 I 9104 26106 2376 286

JEANERETTE LA 1935

I 3 Colonizedbullbullbull 200 SO 50 2833 1465 52 3 Butler 200 5100 2845 714 lQ 3 Checkbullbull__ bull __ 200 3550 2807 424 If

1 CO 200 plant

-I Colonized 200 4200 2829 495 14 DlltIer 200 4150 2746 55-1 144 Cbeck 200 5500 27-15 747 20

7 Colonlzed_ 200 9400 2341 2542 35Co 281 tlrst stubble J 7 Butler__ 200 8600 2272 254S a9

Check I 7 __ ~OO 7550 2240 1741 24

S Colonized 200 6000 2001 884 11 li llulTcr 200 6050 2642 927 14 Ii Check 200 7600 2464 1494 30

P O J 213 planL f

1 10 Colonizell 200 8550 2 7Z~ 1774 4 10 Dutler 200 8750 2688 1827 3~ 10 Cbeck bullbull ~OO 8700 2 i3i 1980 45

c13 Colonized 200 7600 2585 1613 511 Co 200 frrs~ stubble c13 BuITer 200 8750 2454 2205 99

c13 Check 200 7400 24iS 1542 72

14 Colonized 200 7000 2 [89 1590 2-5ICo 281 first stubble 11 BulIer 200 a950 21054 1602 l31 14 Check 200 7900 2122 1706 21

cl9 Colonized 200 so 00 2104 2091 34Co 281 SetOnd stubble_ f c19 BuITer 200 8250 2203 2065 52

1 c19 Cbeck 200 S500 ~ lSi 2457 58

c20 Colonized 200 8750 2208 2310 48 Co 281 tlrs~ stubble J c20 Dutr~l 200 8700 2319 2678 62

c20 Check bullbullbullbull 200 9150 2350 2651 58It -----------shy

rOIOnIZed - 1800 7500 22473 1598 32 Total and average BuITer __ 1800 7256 22 323 1627 347

Check 1800 7350 22100 1593 3toI

IIOUfA LA 1935

I 21 IColonized 200 955 2674 2273 16 21 Dutrer 200 890 2756 1923 14 21 Check 200 715 2809j 1399 13P 01234 first stubble__bullbull 22 i Colonized 855 2 726 I 1988 15 22 I DutIer 855 2 773 r 1550 411 ~I22j Cbeck 200 875 2822 i 1743 81

23 Colonized 700 2853 999 5

c P S07 first stubble 23 Butrer 010 2830 7511 6 23 Cbeck 515 2974 55S 6

26 TECHl1CAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 12-Ezperilllents in the mass liberation of Trichogralllma minutulII Inshyfestation by the sugarcane borer in colonized buffer and check plots of sugarcane as judged by Ihe 1Iumber of stalks and joints bored-Continued

1I0UMA LA 1935-Continncd

Stalks Joints Plot ExitVureity and crop TreatmentNo holesTotal exmiddot lolIlexmiddotBored Boredumincd nmined

------------Numter Percent Number Percent Number

24 COlonizedl 200 35 2554 1237 8 24 BulIerbullbullbullbullbull 200 810 257i 1428 11 24 Checkbullbullbullbullbull 200 885 2649 1902 11

25 Colonizedbullbull 200 870 2118 2304 16 00 28Ifirst stubblebullbullbullbullbull 21 Bufferbull 200 845 2 J06 1904

25 Checkbullbullbull_bullbull 200 SO 0 2150 1576 13

26 Colonizedbullbull 200 885 2049 2464 20 26 Buffer 200 SO 0 2178 1969 16 26 Check 200 855 2200 2068 15

27 Colonized bull 200 820 2751 1828 19C~ 281 plant 27 Buffer 200 SO 0 2667 1646 14 27 Check 200 890 2704 2192 26

c30 Colonized 200 63bull 5 2784 916 9 C P S07 first stubble c30 BulIer 200 720 2824 1168 12

c30 Check____ bull 200 600 2740 S 36 10

031 Colonized __ 200 025 2332 2706 9 011 Buffer __ 200 935 2428 2900 13 031 Cheek__ 200 920 2487 2786 I

e32 Colonized 200 915 2316 2772 6 Co 281 first stubble ____ 032 Buffer __ bull 200 820 2319 2OS7 13

032 Check 200 840 2269 2168 23

18 ~331 BuffeL 200 680 2474 1370 12

I c33 Colonized__ 200 760 2240 1870

e33 Cheek__ __ 200 680 2412 1335 17

IrolonizCd 1 2200 8232 27397 lP03 HI Total and average __ Duffer__ 2200 964 27932 1676 137 ICheck __bull __ 2200 I 7850 28276 1659 a9

Itmay be noted that in most of the experiments the borer infestation was high thus allowing an opportunity for a wider difference in infesshytation between colonized plots and check plots The results of these experiments show that the borer infestation in the colonized plots increased to as great an extent as in the check plots notwithstanding the large number of Trichogramma released

The number of joints and stalks for examination was not selected because it was thought the bost unit for a sample as the reliability of sampling data increases with the size of the sample but because it was as large a sample as could be obtained per plot at that time of year with the help available

An individual record was kept of each stalk examined To secure the standard deviation in the percentage of infestation and the coeffishycient of variation the stalks examined in the Jeanerette area in 1934 were grouped in sets of 10 each The variants in percentage of infestashytion were grouped in classes ranging in percentage of joint infestation from 1 to 5 6 to 10 etc and calculations werc based on the ccnters of the class intervals The results of these calculations are given in table 13

It will be noted that the coefficient of variation is rather high It is not so great however but that the mean percentage of infestation of a sample of 200 stalks can be used to give a fairly representative picture

---------------

EXPERIlgtIENTS FOR CONTROL OF SUGARCANE BORER 27

of borer injury in a given plot This is especially true where there is a difference in the mean of 5 percent or more between 2 plots of the same experiment TABLE l3-Percentage of joint infestation of 20 bundles of 10 stalks each of sugarCGtle

in experiments on the maS8 liberations of Trichogramma minlltum to control Ihe sugarcane borer Jeanerette La 1934

Plot Standard CoefficientVariety and crop Treatment MeanNo doviation of variation

Percent Prrcf1t Percf1t 1 Colonlzedbull__ 2575 74958 2911

P o 1 213 first stubble bullbull _bull____bullbull_bull_bullbull 1 Buller__ _bull_ 3181 109005 342i 1 Check bull __bullbull 3150 95000 3016

Colonized2 ____ 2875 84075 2924Buller________ P O J 213 second stubble bullbullbullbullbull _____________ 2 2i28 90043 3631Check________2 1500 76485 5000

Colonized _____3 2150 124500 5795P O J 234 pianL __________________________ Buller_________3 2125 84075 3956Check_________3 2200 68100 3000

4 Colonized _____ 2600 85732 32 97 Buller_________ Check_________ Co 281 first stubble ______ bull____ bull____________ 4 252i 55845 2212

4 1750 61032 3488

Colonized_____7 3550 118848 3348Co 281 plan __________________ bull__________ bull Buller_________7 3825 1112[4 2908Check_________7 4225 131600 3115

8 Colonized_ 2375 lOliS1 4277 P O J 234 first stubble ____bullbullbullbullbullbull_bullbullbull 8 Buller___ 2875 85i49 2916

8 Check 2650 116297 4389

Colonized ]800 68920 3829 9 Buller__bull___ 1625 55396 34099

9 Check__ 1575 8 bull iS41 MlO P O gtML

10 Colonized 5750 90691 1577 lO Buller___ 4875 12 7744 2620 10 Check_____ 4725 lO4013 2201

In addition to the external count of the bored joints a number of stalks vere split each year and an internal examination and count was made of the actual number of joints bored and borer larvae pupae and pupal skins found A summary of the data obtained through splitting the canes in the various experiments in the years 1933 1934 and 1935 are shown in table 14

TABLE 14-Summary of infestation by the sugarcane borer in the canes 3plit in the Trichogrammo plots Louisiana 1933-35

Joints Joints Stalks Total bored bored Pupal Exit

Year and loeality Plot treatment split joints edermiddot Internmiddot Larvae Pupae skins holes Dally ally

Number Number Number Number NumberNumberlNumber Numb 1933 JelDPrette

and Houma cornmiddot bined

COlOnized ButTerCheck ___ bull__ bull

700 285 600

8 fi38 368-1 i688

3140 1028 2398

3359 1130 2556

289 86

181

10 6 2

167 37

109

225 2 3

4 13

COlOnized 1934 Jeanerette RuITer_ ____

Check_______

500 500 500

fi82S 5778 5685

1 i73 1789 152

1844 18middot18 1677

43 41 4-1

7 1 1

101 125 131

HI 1 68 161

IrOIODIZCd --1914 lIouma __ ____ Buller _

Check

500 500 gt00

61411 11540 6411

1817 1541 1492

205i 1692 1630

is 67 53

3 7 4

99 7 is

1 05 68 59

COIOnizcd____ 1935 Houma_____ RutTer

Oheck __

550 5501 550

7140 I 141-11200 I 7152 1223 1170 72 I 1187 1336

76 r flS r M

f

1 2 2

31 39 40

1 3 4

36 9 5

28 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

EFFECT OF COLONIZATIONS ON PERCENTAGE OF MUJLABLE CANE

It is a well-known fact that a large percentage of the cane plants produced each season never reach millable size There are probably several factors involved in the loss of such a Jarge nUlXlber of plants Many of them die or become stunted through lack of light and possibly plant food

Hinds Osterberger and Dugas (7) investigated the effect of the borer in causing unmillable cane and reported that

The effect of Trichogramma colonization upon the proportion of original stalks developing to millable size and condition appears to be significant and yields some very interesting comparisons which indicate the value of early season colonization

A further study was made by the writers of the value of Trichoshygramma colonizations in increasing the percentage of millable cane in the colonized buffer and check plots in two experiments carried on cooperatively with the Louisiana Agricultural Experiment Station in 1934 and in four cooperative experiments in 1935 Plants clas8ed as unmillable included all that were dead or so small that they would have been left in the field with the trash nt harvest time These unmillable plants were split to determine the percentage injured by the borer Examinations of like character were made in both year in cane growing near Rosewood and Bunkie La where borer injmy is the lightest ill the sugar district as it is interesting to compare findings there with those from the coopell1tin experiments in which borer injury was much above the average for the sugar district Data covering these examinations an given in tahle 15

TBLE I5-Effects of Trichogramma colonization and sugarcane borer injury on the percentage of millable sugarcane plants Louisiana 1934-35

Snm t I Plants not Trichooramma experiment No Dato Ill bull mlllable

variety and crop Plot treatment ewmmiddot exnlll MlIIable plants _____

ined _________________I____ Ined I II_Total IBored

1934 Numlm Number PercentNumber Percent Colonizedbullbullbull Dec 10 6 312 -n7 341 141

cl Co 281 plant Cmebullbullbull ___ __ Butr~rbullbullbullbullbull do __ bullbull 6 301 87 321 168Check_____bull__ do_ ___ 6 317 522 290 148

COlOnized ___ No 20 l 244 537 210 228e2 P O J 234 plan cane_ ____ Buffer_ ___ bull bull__ do___ bull 6 283 551 ZlO 117

_bull do __bull 246 171(RosewoodmiddotBunkie area) ICheek____ bullbull__ 6 589 152 2 33 1308 590 907b~028r~4_~~~ Oct

do _

2 I 103middot1 566 791 8 5

1915 COlOnized ____ Oct 17 665 159 25

e30 C P B07 stubble cane___ bull___ DuifeL _do ___ Ii I 3l51 602 153 48JQO Check_ 321 f 63~ 157 102bullbull bullbullbulldo____

1 COlOnized __ Nov 20 ~ I 2lfi I li39 25- 107

031 Co 281 stuhble eane_____ BufTer______ do __ bull Ii 270 I 498 272 HO

jI ChCCkmiddotmiddotmiddot ___middotImiddotdO - bull

~ I 271 54B 2J5 147 (COlOnized do ___ 485 300 133

281 aL) 21)5 VI~ Co_ bb =-i Cncek_ _____1do__ g I 51 7 266285 9B I COlOnized __ dobull __ r 25j 522 ZH 137

013 Co 281 stUbble t3ne_ ___bull ____ 1 Butfer_ bullbullbull do ____ 6 2m 470 21H 112 (RosewoodmiddotBunkle area) ICheekmiddot-- middotT__ do ___bull 6 253 1 517 236 8

Co 281 plant __bull______ - -_l Oct 10 20 IoJll 534 11Co 281 stubble___ bullmiddot ____ ___ 1 Oct 9 30 1457 1 ~r 2ll0921Co 200 plnet_______ bullbull_____ Oct 10 25 1220 564 9-13 I 00Co 290 stubble___________ _____ ____ 1 Oct 11j

25 1207 I 577 t 882 I 00 I I r

Bnch sample consisted of 10 feet of row

---------------

EXPERIlgtIENTS FOR CONTROL OF SUGARCANE BORER 27

of borer injury in a given plot This is especially true where there is a difference in the mean of 5 percent or more between 2 plots of the same experiment TABLE l3-Percentage of joint infestation of 20 bundles of 10 stalks each of sugarCGtle

in experiments on the maS8 liberations of Trichogramma minlltum to control Ihe sugarcane borer Jeanerette La 1934

Plot Standard CoefficientVariety and crop Treatment MeanNo doviation of variation

Percent Prrcf1t Percf1t 1 Colonlzedbull__ 2575 74958 2911

P o 1 213 first stubble bullbull _bull____bullbull_bull_bullbull 1 Buller__ _bull_ 3181 109005 342i 1 Check bull __bullbull 3150 95000 3016

Colonized2 ____ 2875 84075 2924Buller________ P O J 213 second stubble bullbullbullbullbull _____________ 2 2i28 90043 3631Check________2 1500 76485 5000

Colonized _____3 2150 124500 5795P O J 234 pianL __________________________ Buller_________3 2125 84075 3956Check_________3 2200 68100 3000

4 Colonized _____ 2600 85732 32 97 Buller_________ Check_________ Co 281 first stubble ______ bull____ bull____________ 4 252i 55845 2212

4 1750 61032 3488

Colonized_____7 3550 118848 3348Co 281 plan __________________ bull__________ bull Buller_________7 3825 1112[4 2908Check_________7 4225 131600 3115

8 Colonized_ 2375 lOliS1 4277 P O J 234 first stubble ____bullbullbullbullbullbull_bullbullbull 8 Buller___ 2875 85i49 2916

8 Check 2650 116297 4389

Colonized ]800 68920 3829 9 Buller__bull___ 1625 55396 34099

9 Check__ 1575 8 bull iS41 MlO P O gtML

10 Colonized 5750 90691 1577 lO Buller___ 4875 12 7744 2620 10 Check_____ 4725 lO4013 2201

In addition to the external count of the bored joints a number of stalks vere split each year and an internal examination and count was made of the actual number of joints bored and borer larvae pupae and pupal skins found A summary of the data obtained through splitting the canes in the various experiments in the years 1933 1934 and 1935 are shown in table 14

TABLE 14-Summary of infestation by the sugarcane borer in the canes 3plit in the Trichogrammo plots Louisiana 1933-35

Joints Joints Stalks Total bored bored Pupal Exit

Year and loeality Plot treatment split joints edermiddot Internmiddot Larvae Pupae skins holes Dally ally

Number Number Number Number NumberNumberlNumber Numb 1933 JelDPrette

and Houma cornmiddot bined

COlOnized ButTerCheck ___ bull__ bull

700 285 600

8 fi38 368-1 i688

3140 1028 2398

3359 1130 2556

289 86

181

10 6 2

167 37

109

225 2 3

4 13

COlOnized 1934 Jeanerette RuITer_ ____

Check_______

500 500 500

fi82S 5778 5685

1 i73 1789 152

1844 18middot18 1677

43 41 4-1

7 1 1

101 125 131

HI 1 68 161

IrOIODIZCd --1914 lIouma __ ____ Buller _

Check

500 500 gt00

61411 11540 6411

1817 1541 1492

205i 1692 1630

is 67 53

3 7 4

99 7 is

1 05 68 59

COIOnizcd____ 1935 Houma_____ RutTer

Oheck __

550 5501 550

7140 I 141-11200 I 7152 1223 1170 72 I 1187 1336

76 r flS r M

f

1 2 2

31 39 40

1 3 4

36 9 5

28 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

EFFECT OF COLONIZATIONS ON PERCENTAGE OF MUJLABLE CANE

It is a well-known fact that a large percentage of the cane plants produced each season never reach millable size There are probably several factors involved in the loss of such a Jarge nUlXlber of plants Many of them die or become stunted through lack of light and possibly plant food

Hinds Osterberger and Dugas (7) investigated the effect of the borer in causing unmillable cane and reported that

The effect of Trichogramma colonization upon the proportion of original stalks developing to millable size and condition appears to be significant and yields some very interesting comparisons which indicate the value of early season colonization

A further study was made by the writers of the value of Trichoshygramma colonizations in increasing the percentage of millable cane in the colonized buffer and check plots in two experiments carried on cooperatively with the Louisiana Agricultural Experiment Station in 1934 and in four cooperative experiments in 1935 Plants clas8ed as unmillable included all that were dead or so small that they would have been left in the field with the trash nt harvest time These unmillable plants were split to determine the percentage injured by the borer Examinations of like character were made in both year in cane growing near Rosewood and Bunkie La where borer injmy is the lightest ill the sugar district as it is interesting to compare findings there with those from the coopell1tin experiments in which borer injury was much above the average for the sugar district Data covering these examinations an given in tahle 15

TBLE I5-Effects of Trichogramma colonization and sugarcane borer injury on the percentage of millable sugarcane plants Louisiana 1934-35

Snm t I Plants not Trichooramma experiment No Dato Ill bull mlllable

variety and crop Plot treatment ewmmiddot exnlll MlIIable plants _____

ined _________________I____ Ined I II_Total IBored

1934 Numlm Number PercentNumber Percent Colonizedbullbullbull Dec 10 6 312 -n7 341 141

cl Co 281 plant Cmebullbullbull ___ __ Butr~rbullbullbullbullbull do __ bullbull 6 301 87 321 168Check_____bull__ do_ ___ 6 317 522 290 148

COlOnized ___ No 20 l 244 537 210 228e2 P O J 234 plan cane_ ____ Buffer_ ___ bull bull__ do___ bull 6 283 551 ZlO 117

_bull do __bull 246 171(RosewoodmiddotBunkie area) ICheek____ bullbull__ 6 589 152 2 33 1308 590 907b~028r~4_~~~ Oct

do _

2 I 103middot1 566 791 8 5

1915 COlOnized ____ Oct 17 665 159 25

e30 C P B07 stubble cane___ bull___ DuifeL _do ___ Ii I 3l51 602 153 48JQO Check_ 321 f 63~ 157 102bullbull bullbullbulldo____

1 COlOnized __ Nov 20 ~ I 2lfi I li39 25- 107

031 Co 281 stuhble eane_____ BufTer______ do __ bull Ii 270 I 498 272 HO

jI ChCCkmiddotmiddotmiddot ___middotImiddotdO - bull

~ I 271 54B 2J5 147 (COlOnized do ___ 485 300 133

281 aL) 21)5 VI~ Co_ bb =-i Cncek_ _____1do__ g I 51 7 266285 9B I COlOnized __ dobull __ r 25j 522 ZH 137

013 Co 281 stUbble t3ne_ ___bull ____ 1 Butfer_ bullbullbull do ____ 6 2m 470 21H 112 (RosewoodmiddotBunkle area) ICheekmiddot-- middotT__ do ___bull 6 253 1 517 236 8

Co 281 plant __bull______ - -_l Oct 10 20 IoJll 534 11Co 281 stubble___ bullmiddot ____ ___ 1 Oct 9 30 1457 1 ~r 2ll0921Co 200 plnet_______ bullbull_____ Oct 10 25 1220 564 9-13 I 00Co 290 stubble___________ _____ ____ 1 Oct 11j

25 1207 I 577 t 882 I 00 I I r

Bnch sample consisted of 10 feet of row

28 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

EFFECT OF COLONIZATIONS ON PERCENTAGE OF MUJLABLE CANE

It is a well-known fact that a large percentage of the cane plants produced each season never reach millable size There are probably several factors involved in the loss of such a Jarge nUlXlber of plants Many of them die or become stunted through lack of light and possibly plant food

Hinds Osterberger and Dugas (7) investigated the effect of the borer in causing unmillable cane and reported that

The effect of Trichogramma colonization upon the proportion of original stalks developing to millable size and condition appears to be significant and yields some very interesting comparisons which indicate the value of early season colonization

A further study was made by the writers of the value of Trichoshygramma colonizations in increasing the percentage of millable cane in the colonized buffer and check plots in two experiments carried on cooperatively with the Louisiana Agricultural Experiment Station in 1934 and in four cooperative experiments in 1935 Plants clas8ed as unmillable included all that were dead or so small that they would have been left in the field with the trash nt harvest time These unmillable plants were split to determine the percentage injured by the borer Examinations of like character were made in both year in cane growing near Rosewood and Bunkie La where borer injmy is the lightest ill the sugar district as it is interesting to compare findings there with those from the coopell1tin experiments in which borer injury was much above the average for the sugar district Data covering these examinations an given in tahle 15

TBLE I5-Effects of Trichogramma colonization and sugarcane borer injury on the percentage of millable sugarcane plants Louisiana 1934-35

Snm t I Plants not Trichooramma experiment No Dato Ill bull mlllable

variety and crop Plot treatment ewmmiddot exnlll MlIIable plants _____

ined _________________I____ Ined I II_Total IBored

1934 Numlm Number PercentNumber Percent Colonizedbullbullbull Dec 10 6 312 -n7 341 141

cl Co 281 plant Cmebullbullbull ___ __ Butr~rbullbullbullbullbull do __ bullbull 6 301 87 321 168Check_____bull__ do_ ___ 6 317 522 290 148

COlOnized ___ No 20 l 244 537 210 228e2 P O J 234 plan cane_ ____ Buffer_ ___ bull bull__ do___ bull 6 283 551 ZlO 117

_bull do __bull 246 171(RosewoodmiddotBunkie area) ICheek____ bullbull__ 6 589 152 2 33 1308 590 907b~028r~4_~~~ Oct

do _

2 I 103middot1 566 791 8 5

1915 COlOnized ____ Oct 17 665 159 25

e30 C P B07 stubble cane___ bull___ DuifeL _do ___ Ii I 3l51 602 153 48JQO Check_ 321 f 63~ 157 102bullbull bullbullbulldo____

1 COlOnized __ Nov 20 ~ I 2lfi I li39 25- 107

031 Co 281 stuhble eane_____ BufTer______ do __ bull Ii 270 I 498 272 HO

jI ChCCkmiddotmiddotmiddot ___middotImiddotdO - bull

~ I 271 54B 2J5 147 (COlOnized do ___ 485 300 133

281 aL) 21)5 VI~ Co_ bb =-i Cncek_ _____1do__ g I 51 7 266285 9B I COlOnized __ dobull __ r 25j 522 ZH 137

013 Co 281 stUbble t3ne_ ___bull ____ 1 Butfer_ bullbullbull do ____ 6 2m 470 21H 112 (RosewoodmiddotBunkle area) ICheekmiddot-- middotT__ do ___bull 6 253 1 517 236 8

Co 281 plant __bull______ - -_l Oct 10 20 IoJll 534 11Co 281 stubble___ bullmiddot ____ ___ 1 Oct 9 30 1457 1 ~r 2ll0921Co 200 plnet_______ bullbull_____ Oct 10 25 1220 564 9-13 I 00Co 290 stubble___________ _____ ____ 1 Oct 11j

25 1207 I 577 t 882 I 00 I I r

Bnch sample consisted of 10 feet of row

29 EXPERIlIENTS FOR CONTROL OF SUGAROANE BORER

It may be noted that the percentage of mill able plants was as great in the uncolonized as in the colonized plots Borer injury to unmillshyable cane was also practically the same in colonized and check plots

Comparing the percentage of millable plants in the heavily bored plots of the Trichogramma experiments with the percentage in the Rosewood-Bunkie area little correlation is apparent between borer injury and the percentage of millable plants

The results of examinations made at Rosewood during the harvest season of 1934 are of special interest since a total of 850 millable stalks were examined without finding any indication of borer injury In spite of the absence of borers the percentage of plants too small to be millable was almost as high as in the Houma area

YIELD IN SUGAR AND CANE PER ACRE

The final conclusion on whether the release of Trichogramma minushytum is of value in the control of the sugarcane borer must be based on the quantity of sugar produced per acre of cane in the colonized areas in excess of that produced in the areas where no parasites were reshyleased This increase -if sugar might result from greater tonnage of sugarcane or from more sugar per ton of cane due to less borer injury or from both

In 1933 an observer checked all the cars loaded from experimental plots to obtain the correct net weight of cane from each plot Five or six plantation carloads from each plot were tagged with a special card indicating that they were to be milled together and a composite sample taken by the factory chemist

In 1934 and 1935 the same method of obtaining the net weight of cane and the factory mill sample was used as in 1933 except that the weight and also a factory juice sample of each cut in each plot were obtained Where possible four or more plantation carloads were tagged from each cut for a composite juice sample and in the Houma experiments one or more composite samples were taken from all the cane in each cut In some experiments the cane was hauled to the mill by motortruck or wagon and in such cases two wagonloads per cut were used for a sample In selecting wagonloads and cllrloads for sucrose analyses where the entire cut was not used for a sample care was taken during all three seasons to get cane from the middle of the cuts and not from the heap rows along the drain ditches

As a precaution against failure to get analyses of factory juire analyses were also made by use of a small milL In 1933 150 stalks were cut from each plot 15 stalks from 10 representative points that is 4 points near each end and 2 in the middle In 1934 and 1935 10 stalks were taken at 5 representative points in each plot or at 6 points in 1934 when there were 3 cuts of cane in the plot These samples were ground in the experimental mill of the Division of Soil Fertility of the Bureau of Plant Industry at Houma In 1933 and 1934 juice analyses were made tmder the supervision of N MeKaig Jr and in 1935 the analyses were made under the supervision of A )f ONeal or G ArcenemL~ The comparative analyses between the 3 plots of an experimeni when obtained by small-mill samples agreed very closrly with the factory-juice analyses from the same 3 plots The figures for the small-mill anillyses were often lower than those of the factory analyses for the same experiment as the small samples were taken

30 TEOHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

sometimes several days before the cane of the experiment was harshyvested It was apparant that factory analyses of wagonload and carload lots were more accurate than small-mill samples from a small number of stalks for detennining the sugar produced per acre

Table 16 gives the data from the various experiments showing the nUmber of acres per plot pounds of 96deg sugar per ton of cane calculated from both the small-mill analyses and the factory analyses tons of cane harvested per acre and the pounds of 96deg sugar per acre based on the factory analyses It may be noted that in 1933 only one colonized plot 20-P surpassed its check in both pounds of sugar per ton of cane (factory analysis) and pounds of sugar per acre There was one colonized plot 9-P which surpassed its check in pounds of sugar per ton of cane but it was below its check in pounds of sugar per acre and 113-P and 124-P surpassed their checks in pounds of sugar per acre but were below the checks in pounds of sugar per ton of cane on the basis of factory analysis In comparing the averages of the colonized buffer and check plots it may be noted that the yield of the check plots surpassed that of the colonized plots by 103 pounds of sugar per ton of cane and by 220 pounds of sugar per acre The buffer plots gave le~s sugar per ton of cane but more sugar per acre than either colonized or check plots

TABLE l6-Yield of sugar and related dala on the collmized buffer and check plot in the experiments 1m the maS8 liberations of Trichogromma minutum in Louisiana 1933-35

COMBINED D-T- FROM HOU~L- AND JEANERETTE EXPERD1ENTS 1933

I ru_~~~_

j Sugar ~--- ~~~

IPlot SIze of Smallmiddotmlll FactQr analysis i Cane ld

Variety and crop No Treatment i plot I analysis ~~ on fac I tory

1Q Quanmiddot 1 analymiddotII I 1Date cut th Date cut tity 1 r sis l f I 1 t t

------1------ ---j--I---I----)--I IAcrt I Pound Pornd Tom PoundI [ I ColonIzed 2 i3 I Oct 12 I 1185 t Oct 21 I 1221 I 1584 1934

ButTer 288 -dO j1424 tmiddotmiddotmiddot dO bullbullbull ISS1 1 15M j 2460I 3 2

Check____ i 299 i _do _ 1140 do _ i 1450 i 1745 2530

4 Colonized _J 749 I Oct 13 I 1372 Oct 19 16O9 1542 2481 5 ButT~r bullbull _ 390 do l 1457 do ~ 1590 I 150lt I 2393 6 Ch~ck 712 do 11510 bulldo bullbull 1646 1571 I 25M

P O J 234 first 7 ButTer 2 91 1middotmiddotmiddotdo -- 1310 do i 1432 IiOI 243fl stubble 81 Colonlzed _ 824 1middotmiddot-do 1263 do 1347 i 1568 2112

20 Colonized bullbull _bull 19 is Oct 10 I 12112 Oct 26 i 1385 Ii 71 2451 I ~ I ButTe~ __ ~24 i lt10 _ 12117 do ~i 1770 23S

t ii 1~Z~(-l ~ ~~9 ~i i ~~~~l14i21 i~ i ~~ 11I5 Check i 1500 bulldo WO4 i do _ 1664 1127 1875 I i

P 0 J 234 plant 109 CQlonized 1828 Xov 161 1811 Dec 6 1~26 711 1408 --llll Check_ 2628 do 1 1673 dO 1005 iiIImiddot lfiB

I I fj9 i Colonzed bull _ 350 Nov 27 I 1826 Dec 2 1581 1911 3021110 ButTer _ 3amp1 bullbull do 1837ilo_ 147R 22S7 33-O

P O J213Plant 11 Checkbull_ 392 do i 1613 do 1419 2226 3159 1 1 12 Colonized _ 789 I do middot_1 1661 Dec 7 1331 1658 2217 16 Check _ 1299 do 1S57middot Dec 6 ISS 4 1723 2618

-------------------

---------

31 EXPERIlIENTS FOR CONTROL OF SUGARCANE BORER

TABLE 16-Yield of Bugar and related data on the colonized buffer and check plot in the ezperiments on the maBB liberations of Trichogramma minutum in Louisiana 1988-85-Continued COMBINED D~TA FROM BOUM- AND JENERETTE EXPERIMENTS 1933-Con

96deg sugar per ton of cane Sugar per

SmallmiddotroUl Cane acre Plot SIIeof Factory analysis basedVariety and crop Treatment IUlBlysis perNo plot

acre on facmiddot tory

analymiddotQuanmiddot D QuanmiddotD ate cut tlty ate cut tlty sis

ACTt Poundl Poundl Tom Pound19 Colonizedbullbullbullbullbull 854 Oct 20 1312 Oct 29 1060 2352 249318 Butler bullbullbullbullbullbull 601 do bullbull 1316 do bullbullbullbullbull 1254 1860 2332 1 Checkbullbullbullbullbullbullbullbullbull 876 bullbullbulldo bullbull 1379 No 4 1256 1990 2500

P O 1 213 f1tst 106 Colonizedbullbullbullbullbull 1329 Nov 6 1488 Nov 13 1313 960 1260stubble lOi Check 2350 bullbulldobullbullbull 1690 No 15 liii 991 1761

lOS Colonizedbullbullbullbullbull 2610 bull dobullbull 1645 Nov 13 1663 956 1590

12i Colonizedbullbull 449 ~ov 9 1616 Nov 10 1767 1440 2544 126 Check 1279 bulldo 1590 do bullbull 1848 1717 3173

1900 bullbulldobullbullbull 1315 Nov 9 1351 445 601 125 Checkbullbullbullbullbullbull 1965 bullbulldobullbullbullbull 1404 Nov a 1379 408 563

P 01 213 second r CoLshystubble 113 CoIQnized 801 Oct 20 1005 Oct 28 101 5 1646 1671

14 bull ButIer 320 Ido bullbullbullbull 919 bullbullbulldo bullbullbullbullbull 1117 18amp4 2 lOt 15 Checkbullbullbullbullbullbull ~rdObullbullbullbullbull 1121 bullbulldo 1153 1695 1954

1463 1425 1421 2025f4 Colonized bull 1159 r a _______ ~verages bullbullbullbullbullbullbullbull+ 8 Butlerbullbullbullbullbull_ 524 bullbullbullbullbullbullbullbullbull 1405 1393 1i41 2425 12 Check_ 1250 I 1507 -------- - 1528 14611 2 245

BOUMA EXPERIMENTS 1934

c1 IColonized 5361 Nov 6 1608 Dec 29 1382 2583 3570 Co 281 planL e1 Butler 551 Ido 1710 bulldo 1446 2600 3760 c1 ICheck 510 do 1880 Dec 28 1455 2416 Q515

c2 Colonized 319 do 1746 Dec 19 1496 1670 2 ~98 P 01 234 plant c2 Butler 456ldO ISO 8 Dec 18 1389 1881 2613

c2 Check 2 98 do 172 2 Dec 16 1487 1809 2 690

3 Co1unized 356 Oct 12 1589 Nov 15 1869 1683 3 146 P O 1 213 first 3 ButI~r 6SSIbullbullbulldo 1624 bullbullbulldobull 1002 1723 3277stUbble 3 Check 452 bullbullbulldobullbullbull 1637 do 1923 1822 3504

4 Colonized 496 do 11327~middot271 00eCtt 2726 1618 1291 2OSlP O 1213 second 4 I Butler 708 J bullbullbull do 1669 1231 2054

stubble I 4 i Check i 305 Imiddotdo 1470 lmiddotdo 1633 12 29 i 2 007

15 Colonized 315 do 152 5 Oct 20 IiI 2 13161 2 253 5 RutIer 510 bullbullbulldo 1475 Oct 21 1669 1322 2 206

1 5 Check 349 do 15i8 bullbullbulldo 1816 12 22 2 211

Pmiddotst~bJ~ 234 first I 6 Colonized 4fJl do 1 lMO Ort 22 I 1671 1288 21~2 6 ButIer i18 do 1M0 dObullbullbullbullbull 1679 131131 2322 6 iCheck bullbullbullbullbullbull 476 bullbullbulldo 1551 bullbullbulldo 1671 1240 2 072

7 Colonized 335 bullbullbulldo 1464 Oct 181 1533 I 1409 I 2 160 7 ButTer 377 1 do HI3 j Oct 17

Ij 1466 HS2 2 173

7 Check 405 j do 138 bullbulldo1 1422 13OS 1860

8IColonlzed 325jbullbullbulldo bullbullbullbull 1474 oet241172ojI611 2771 P 01 213 first 8 ButTer 4751 bullbullbull dO ISQ2 do bullbullbull 1714middot 1766 3027

stubble 8 Check 322 bull do 1486 bull dobullbull 1741 1585 2 759

(Ill ColonltcltL 337 bullbulldo1 1576 Oct 2G 1780 13 H 2339 9 BulItmiddotr 484 bullbullbulldo 11134 Oct 2511697 1535 2605 91 Check 30Ij dO 1460 do 1677 1640 2750

10 Colonlzed j 426 bullbulldo 1674 Oct 19 1663 1400 2478 P O 1 234 first 10 Butler ~33 do 154 do 1602 H(J 2371

stubble IO Checkmiddotmiddotmiddotmiddot middotl 322 1 dOmiddot ~11 Oct 20 1 1589 I 1370 I 2177j

Colonized 300 1 1M7 1644 1566 2575 Averages1DutI(r 1566 1M Ii 1623 1640 2002

Check 374 ( 1572 1 1641 1564 2567j 1 1

30 TEOHNIOAL BULLETIN 743 U S DEPT OF AGRICULTURE

sometimes several days before the cane of the experiment was harshyvested It was apparant that factory analyses of wagonload and carload lots were more accurate than small-mill samples from a small number of stalks for detennining the sugar produced per acre

Table 16 gives the data from the various experiments showing the nUmber of acres per plot pounds of 96deg sugar per ton of cane calculated from both the small-mill analyses and the factory analyses tons of cane harvested per acre and the pounds of 96deg sugar per acre based on the factory analyses It may be noted that in 1933 only one colonized plot 20-P surpassed its check in both pounds of sugar per ton of cane (factory analysis) and pounds of sugar per acre There was one colonized plot 9-P which surpassed its check in pounds of sugar per ton of cane but it was below its check in pounds of sugar per acre and 113-P and 124-P surpassed their checks in pounds of sugar per acre but were below the checks in pounds of sugar per ton of cane on the basis of factory analysis In comparing the averages of the colonized buffer and check plots it may be noted that the yield of the check plots surpassed that of the colonized plots by 103 pounds of sugar per ton of cane and by 220 pounds of sugar per acre The buffer plots gave le~s sugar per ton of cane but more sugar per acre than either colonized or check plots

TABLE l6-Yield of sugar and related dala on the collmized buffer and check plot in the experiments 1m the maS8 liberations of Trichogromma minutum in Louisiana 1933-35

COMBINED D-T- FROM HOU~L- AND JEANERETTE EXPERD1ENTS 1933

I ru_~~~_

j Sugar ~--- ~~~

IPlot SIze of Smallmiddotmlll FactQr analysis i Cane ld

Variety and crop No Treatment i plot I analysis ~~ on fac I tory

1Q Quanmiddot 1 analymiddotII I 1Date cut th Date cut tity 1 r sis l f I 1 t t

------1------ ---j--I---I----)--I IAcrt I Pound Pornd Tom PoundI [ I ColonIzed 2 i3 I Oct 12 I 1185 t Oct 21 I 1221 I 1584 1934

ButTer 288 -dO j1424 tmiddotmiddotmiddot dO bullbullbull ISS1 1 15M j 2460I 3 2

Check____ i 299 i _do _ 1140 do _ i 1450 i 1745 2530

4 Colonized _J 749 I Oct 13 I 1372 Oct 19 16O9 1542 2481 5 ButT~r bullbull _ 390 do l 1457 do ~ 1590 I 150lt I 2393 6 Ch~ck 712 do 11510 bulldo bullbull 1646 1571 I 25M

P O J 234 first 7 ButTer 2 91 1middotmiddotmiddotdo -- 1310 do i 1432 IiOI 243fl stubble 81 Colonlzed _ 824 1middotmiddot-do 1263 do 1347 i 1568 2112

20 Colonized bullbull _bull 19 is Oct 10 I 12112 Oct 26 i 1385 Ii 71 2451 I ~ I ButTe~ __ ~24 i lt10 _ 12117 do ~i 1770 23S

t ii 1~Z~(-l ~ ~~9 ~i i ~~~~l14i21 i~ i ~~ 11I5 Check i 1500 bulldo WO4 i do _ 1664 1127 1875 I i

P 0 J 234 plant 109 CQlonized 1828 Xov 161 1811 Dec 6 1~26 711 1408 --llll Check_ 2628 do 1 1673 dO 1005 iiIImiddot lfiB

I I fj9 i Colonzed bull _ 350 Nov 27 I 1826 Dec 2 1581 1911 3021110 ButTer _ 3amp1 bullbull do 1837ilo_ 147R 22S7 33-O

P O J213Plant 11 Checkbull_ 392 do i 1613 do 1419 2226 3159 1 1 12 Colonized _ 789 I do middot_1 1661 Dec 7 1331 1658 2217 16 Check _ 1299 do 1S57middot Dec 6 ISS 4 1723 2618

-------------------

---------

31 EXPERIlIENTS FOR CONTROL OF SUGARCANE BORER

TABLE 16-Yield of Bugar and related data on the colonized buffer and check plot in the ezperiments on the maBB liberations of Trichogramma minutum in Louisiana 1988-85-Continued COMBINED D~TA FROM BOUM- AND JENERETTE EXPERIMENTS 1933-Con

96deg sugar per ton of cane Sugar per

SmallmiddotroUl Cane acre Plot SIIeof Factory analysis basedVariety and crop Treatment IUlBlysis perNo plot

acre on facmiddot tory

analymiddotQuanmiddot D QuanmiddotD ate cut tlty ate cut tlty sis

ACTt Poundl Poundl Tom Pound19 Colonizedbullbullbullbullbull 854 Oct 20 1312 Oct 29 1060 2352 249318 Butler bullbullbullbullbullbull 601 do bullbull 1316 do bullbullbullbullbull 1254 1860 2332 1 Checkbullbullbullbullbullbullbullbullbull 876 bullbullbulldo bullbull 1379 No 4 1256 1990 2500

P O 1 213 f1tst 106 Colonizedbullbullbullbullbull 1329 Nov 6 1488 Nov 13 1313 960 1260stubble lOi Check 2350 bullbulldobullbullbull 1690 No 15 liii 991 1761

lOS Colonizedbullbullbullbullbull 2610 bull dobullbull 1645 Nov 13 1663 956 1590

12i Colonizedbullbull 449 ~ov 9 1616 Nov 10 1767 1440 2544 126 Check 1279 bulldo 1590 do bullbull 1848 1717 3173

1900 bullbulldobullbullbull 1315 Nov 9 1351 445 601 125 Checkbullbullbullbullbullbull 1965 bullbulldobullbullbullbull 1404 Nov a 1379 408 563

P 01 213 second r CoLshystubble 113 CoIQnized 801 Oct 20 1005 Oct 28 101 5 1646 1671

14 bull ButIer 320 Ido bullbullbullbull 919 bullbullbulldo bullbullbullbullbull 1117 18amp4 2 lOt 15 Checkbullbullbullbullbullbull ~rdObullbullbullbullbull 1121 bullbulldo 1153 1695 1954

1463 1425 1421 2025f4 Colonized bull 1159 r a _______ ~verages bullbullbullbullbullbullbullbull+ 8 Butlerbullbullbullbullbull_ 524 bullbullbullbullbullbullbullbullbull 1405 1393 1i41 2425 12 Check_ 1250 I 1507 -------- - 1528 14611 2 245

BOUMA EXPERIMENTS 1934

c1 IColonized 5361 Nov 6 1608 Dec 29 1382 2583 3570 Co 281 planL e1 Butler 551 Ido 1710 bulldo 1446 2600 3760 c1 ICheck 510 do 1880 Dec 28 1455 2416 Q515

c2 Colonized 319 do 1746 Dec 19 1496 1670 2 ~98 P 01 234 plant c2 Butler 456ldO ISO 8 Dec 18 1389 1881 2613

c2 Check 2 98 do 172 2 Dec 16 1487 1809 2 690

3 Co1unized 356 Oct 12 1589 Nov 15 1869 1683 3 146 P O 1 213 first 3 ButI~r 6SSIbullbullbulldo 1624 bullbullbulldobull 1002 1723 3277stUbble 3 Check 452 bullbullbulldobullbullbull 1637 do 1923 1822 3504

4 Colonized 496 do 11327~middot271 00eCtt 2726 1618 1291 2OSlP O 1213 second 4 I Butler 708 J bullbullbull do 1669 1231 2054

stubble I 4 i Check i 305 Imiddotdo 1470 lmiddotdo 1633 12 29 i 2 007

15 Colonized 315 do 152 5 Oct 20 IiI 2 13161 2 253 5 RutIer 510 bullbullbulldo 1475 Oct 21 1669 1322 2 206

1 5 Check 349 do 15i8 bullbullbulldo 1816 12 22 2 211

Pmiddotst~bJ~ 234 first I 6 Colonized 4fJl do 1 lMO Ort 22 I 1671 1288 21~2 6 ButIer i18 do 1M0 dObullbullbullbullbull 1679 131131 2322 6 iCheck bullbullbullbullbullbull 476 bullbullbulldo 1551 bullbullbulldo 1671 1240 2 072

7 Colonized 335 bullbullbulldo 1464 Oct 181 1533 I 1409 I 2 160 7 ButTer 377 1 do HI3 j Oct 17

Ij 1466 HS2 2 173

7 Check 405 j do 138 bullbulldo1 1422 13OS 1860

8IColonlzed 325jbullbullbulldo bullbullbullbull 1474 oet241172ojI611 2771 P 01 213 first 8 ButTer 4751 bullbullbull dO ISQ2 do bullbullbull 1714middot 1766 3027

stubble 8 Check 322 bull do 1486 bull dobullbull 1741 1585 2 759

(Ill ColonltcltL 337 bullbulldo1 1576 Oct 2G 1780 13 H 2339 9 BulItmiddotr 484 bullbullbulldo 11134 Oct 2511697 1535 2605 91 Check 30Ij dO 1460 do 1677 1640 2750

10 Colonlzed j 426 bullbulldo 1674 Oct 19 1663 1400 2478 P O 1 234 first 10 Butler ~33 do 154 do 1602 H(J 2371

stubble IO Checkmiddotmiddotmiddotmiddot middotl 322 1 dOmiddot ~11 Oct 20 1 1589 I 1370 I 2177j

Colonized 300 1 1M7 1644 1566 2575 Averages1DutI(r 1566 1M Ii 1623 1640 2002

Check 374 ( 1572 1 1641 1564 2567j 1 1

-------------------

---------

31 EXPERIlIENTS FOR CONTROL OF SUGARCANE BORER

TABLE 16-Yield of Bugar and related data on the colonized buffer and check plot in the ezperiments on the maBB liberations of Trichogramma minutum in Louisiana 1988-85-Continued COMBINED D~TA FROM BOUM- AND JENERETTE EXPERIMENTS 1933-Con

96deg sugar per ton of cane Sugar per

SmallmiddotroUl Cane acre Plot SIIeof Factory analysis basedVariety and crop Treatment IUlBlysis perNo plot

acre on facmiddot tory

analymiddotQuanmiddot D QuanmiddotD ate cut tlty ate cut tlty sis

ACTt Poundl Poundl Tom Pound19 Colonizedbullbullbullbullbull 854 Oct 20 1312 Oct 29 1060 2352 249318 Butler bullbullbullbullbullbull 601 do bullbull 1316 do bullbullbullbullbull 1254 1860 2332 1 Checkbullbullbullbullbullbullbullbullbull 876 bullbullbulldo bullbull 1379 No 4 1256 1990 2500

P O 1 213 f1tst 106 Colonizedbullbullbullbullbull 1329 Nov 6 1488 Nov 13 1313 960 1260stubble lOi Check 2350 bullbulldobullbullbull 1690 No 15 liii 991 1761

lOS Colonizedbullbullbullbullbull 2610 bull dobullbull 1645 Nov 13 1663 956 1590

12i Colonizedbullbull 449 ~ov 9 1616 Nov 10 1767 1440 2544 126 Check 1279 bulldo 1590 do bullbull 1848 1717 3173

1900 bullbulldobullbullbull 1315 Nov 9 1351 445 601 125 Checkbullbullbullbullbullbull 1965 bullbulldobullbullbullbull 1404 Nov a 1379 408 563

P 01 213 second r CoLshystubble 113 CoIQnized 801 Oct 20 1005 Oct 28 101 5 1646 1671

14 bull ButIer 320 Ido bullbullbullbull 919 bullbullbulldo bullbullbullbullbull 1117 18amp4 2 lOt 15 Checkbullbullbullbullbullbull ~rdObullbullbullbullbull 1121 bullbulldo 1153 1695 1954

1463 1425 1421 2025f4 Colonized bull 1159 r a _______ ~verages bullbullbullbullbullbullbullbull+ 8 Butlerbullbullbullbullbull_ 524 bullbullbullbullbullbullbullbullbull 1405 1393 1i41 2425 12 Check_ 1250 I 1507 -------- - 1528 14611 2 245

BOUMA EXPERIMENTS 1934

c1 IColonized 5361 Nov 6 1608 Dec 29 1382 2583 3570 Co 281 planL e1 Butler 551 Ido 1710 bulldo 1446 2600 3760 c1 ICheck 510 do 1880 Dec 28 1455 2416 Q515

c2 Colonized 319 do 1746 Dec 19 1496 1670 2 ~98 P 01 234 plant c2 Butler 456ldO ISO 8 Dec 18 1389 1881 2613

c2 Check 2 98 do 172 2 Dec 16 1487 1809 2 690

3 Co1unized 356 Oct 12 1589 Nov 15 1869 1683 3 146 P O 1 213 first 3 ButI~r 6SSIbullbullbulldo 1624 bullbullbulldobull 1002 1723 3277stUbble 3 Check 452 bullbullbulldobullbullbull 1637 do 1923 1822 3504

4 Colonized 496 do 11327~middot271 00eCtt 2726 1618 1291 2OSlP O 1213 second 4 I Butler 708 J bullbullbull do 1669 1231 2054

stubble I 4 i Check i 305 Imiddotdo 1470 lmiddotdo 1633 12 29 i 2 007

15 Colonized 315 do 152 5 Oct 20 IiI 2 13161 2 253 5 RutIer 510 bullbullbulldo 1475 Oct 21 1669 1322 2 206

1 5 Check 349 do 15i8 bullbullbulldo 1816 12 22 2 211

Pmiddotst~bJ~ 234 first I 6 Colonized 4fJl do 1 lMO Ort 22 I 1671 1288 21~2 6 ButIer i18 do 1M0 dObullbullbullbullbull 1679 131131 2322 6 iCheck bullbullbullbullbullbull 476 bullbullbulldo 1551 bullbullbulldo 1671 1240 2 072

7 Colonized 335 bullbullbulldo 1464 Oct 181 1533 I 1409 I 2 160 7 ButTer 377 1 do HI3 j Oct 17

Ij 1466 HS2 2 173

7 Check 405 j do 138 bullbulldo1 1422 13OS 1860

8IColonlzed 325jbullbullbulldo bullbullbullbull 1474 oet241172ojI611 2771 P 01 213 first 8 ButTer 4751 bullbullbull dO ISQ2 do bullbullbull 1714middot 1766 3027

stubble 8 Check 322 bull do 1486 bull dobullbull 1741 1585 2 759

(Ill ColonltcltL 337 bullbulldo1 1576 Oct 2G 1780 13 H 2339 9 BulItmiddotr 484 bullbullbulldo 11134 Oct 2511697 1535 2605 91 Check 30Ij dO 1460 do 1677 1640 2750

10 Colonlzed j 426 bullbulldo 1674 Oct 19 1663 1400 2478 P O 1 234 first 10 Butler ~33 do 154 do 1602 H(J 2371

stubble IO Checkmiddotmiddotmiddotmiddot middotl 322 1 dOmiddot ~11 Oct 20 1 1589 I 1370 I 2177j

Colonized 300 1 1M7 1644 1566 2575 Averages1DutI(r 1566 1M Ii 1623 1640 2002

Check 374 ( 1572 1 1641 1564 2567j 1 1

32 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

TABLE 16-Yield of sugar and related data on the colonized buffer and check plots in the experiments on the mass liberations of Trichogramma minutum in Louisiana 19S5-S5-Continued

JEANERETTE EXPERIMENTSI9M

96deg sugar per ton of cane Sugar per

Smallmiddotmill Cane acre Plot Size of Factory analysis basedVariety and crop Treatment analysis perNo plot acre on facmiddot

t(lry analymiddotQuanmiddot D QuanmiddotDate cut tity ate cut tity sis

------1middot-1-----1--------------------Acre Poun Pound Tom Poun

Colonizedbullbullbull 784 Oct 18 1830 Oct 30 1925 1223 2354P O J 213 tlrst Buller 9 57 cdo 1753 do 2004 1337 2679stubble Check 523 do 1838 do 1919 1425 2735

2 Colonized 415 do 1791 Nov 2 2025 1035 2096 P O J 213 second 2 Buller 510 do 1826 Nov 1 2040 1051 2152stubble 2 Check 2 14 do 100 1 do 2122 1001 2 124

Colonized 382 Nl 2 1979 Nov 23 1bull 98 3558 P O J 23~ plant Buller__bull 640 do 2023 Nov 22 2184 16 PI 3693

Check 251) do 195 i do 2121 1723 3654

Co 281 tlrst stubble Colonlzed_ 364 Oct 30 2127 Oct 31 1002 1054 2068 Buffer 343 do 2027 do 2085 1016 2 liS Check 331 do 2060 do 2000 1119 2238

7 Colonized 305 Nov 8 1755 Dec 13 2089 2053 4289 Co 281 planL ~ Buller_ 314 do 174 i Dec 19 1985 2104 4176

Check 200 do 1591 do 1831 2196 4027

690 Oct 11 148 4 Oct 23 1624 11 81 1921 middotstubble s 8 Buller__bullbull 690 do 1435 do 1809 1280 2316

8 Check i18 do 139 2 Oct 24 172 5 l1n 2020

P 0 J 234 fir t S Colonized --- shy

9 Colonized _ 297 Nomiddot 5 202 I D(e 4 2342 13Smiddot 4070 if9 Buller_ 6 64 do 1~71 do Z37 li62 3494

9 Cheek__ 448 do 2046 Dec 10 2404 1677 4032

I P O J 234 plant-

10 Colonized 2i1 Nov 2 1541 Nov 13 1593 1559 2483 ( 10 Buller ___bull S02 do l1l24 do 1313 1579 2894

10 Check 234 do 1lO6 do ISO 5 1592 2396

1i37l1[5lColonized 436 __bull __ 1816 2818

Averages Buffer__ bull 577 ____bull IRQ 1 __ 2022 l4oi1 2938 Cheek__ bull 384 ____ bull 1824 __ ~~ 2900

Averace of all experimiddot COlOnized 411 1667 17651517 j 2677 ments Houma and Butfer 566 __ 1670 ____ 1800 1557 I 2R04 Jeanerette in 1934 I Check 379 W84 r-- liSO IS30 223

HOUMA EXPERIMENTS 1935

II( 21 Colonlzed __ 152 r Oct 14 123 01 Oct 24 16-~ 3 15 32 l 2578 21 Bulllr 681 Ido 137 ill do _ 1711 1529 2616shy

21 Check 266 j do __bull 15780 Oct 25 1695 1697 2Si6 P O J 234 first

stubble I 22 Colonized 3191do 140 H LdO 1742 IS 22 3 Ii4 22 ButTer 4 bull 6 I do IlRH bulldo 1710 i 1786 1 3 lOS

1615 i 22 Check 298 bullbullbulldo 12939 f do 1714 2 j68

I 23 COlonized__j 291 I do 19181 Oct 20 I 1434 2213 i 3173 C r 807 tlrststub 23 BlllT(middotr 500 L bull do 1)8513 Oct 20 1458 2385 3477

Lie 23 Cbcek_1 2 6~ l~dO 19181 do 1517 2110 3201

24 1 (olonized R~ Sov 8 22(1Po9 Jao 71 19551 2237 43731

24 ButTer 794 do 299 Jan 8 1843 2351 f 4333 24 Check __ 421 l dO 21566 Jan 9 1734 i 2722 t 4j~

I 21 (olonizl)ltl I R~ Oct 31 11145-1 -ltov Ii 1770 I 1959 3467 Co 281 first stubmiddotmiddot 2 ButTr __ 624 i do 17L 7S lt10 lfoO I 2200 3Si2

233 i __ do I72S9 I do__ 17[6 2102 3867ble 25 Check__ 26 (olonized __ bull __

1 328 do 1738~ I-lto 2 1620 12256 3651

26 Buller 6 13 ~ _do 16217 do bullbullbullbullbull ]~O Z17 3940 26 Check __ bull 476 do 17519 tdo 16671 2128 3547

11936

------------------

---------

----------

33 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

TOBLE 16-Yield of sugar and relate-l data on the colonized buffer and check plots in the experiments on the mass liberations of Trichogramma minutum in Louisiana lBSS-S5-Continued

HOUMA EXPERIMENTS 1935-Continued

00deg sugar per ton of cane Sugar per

Smallmiddotmill Cane acre Plot Size of Factory analysis basedVariety and crop Treatment analysis perNo plot acre on raemiddot

tory analymiddotQuanmiddot QuanmiddotDate cut Date cut sistity tity

ArT Pound Pound8 Ton Poundt Colonizedbullbullbullbull 220 Dec 16 19952 Jan 21 li39 3458 6013

Co 281 plan bullbullbullbullbullbull ~ ButTerbullbullbullbullbullbull 323 bullbulldobullbullbullbullbull 19018 Jan 3 1680 3612 6068 rl Cbeckbullbullbullbullbull 175 bullbulldo bullbull 20779 bullbullbulldobullbullbullbull 1760 3811 6707

r30 Colonizedbullbullbull 262 Oct 17 14621 Oct 30 1587 2580 4094 C P 807 first stubmiddot 030 ButTer _bullbull 506 bullbullbulldo bullbull 15110 Oct 29 1~90 2574 4093

ble e30 Checkbullbullbull_bullbull _ 221 bullbullbulldobullbullbullbullbull 15452 bulldobullbullbullbull 1561 2560 3996

031 Colonizedbullbullbullbull 361 Nov 7 213111 Nov 29 2086 1928 4022 c31 ButTerbullbullbullbull 502 bullbulldo 20322 Nov 30 2002 2023 4010 031 Check____ 481 dobullbull_ 20865 __ do__bull 1825 2239 4086

c32 Colonlzed____bull 109 __ do 21229 Nov 29 2039 182-1 3719 Co 281 first stubmiddot 032 ButTer____ bull 374 __do 21159 Nov 28 2061 1693 3489

Check ________ do__ do __ __ble 032 257 20753 2080 1722 3582

ca1 Colonized____bull 135 __do 21788 Nov rl 2249 1638 3 f84 c33 ButTer __ bull 231 bullbulldo 23538 __do__ 2175 1831 3982

Check _____ 109 __ dobullbullbullbull 23548013 Nov 28 2187 1857 4061

COlonlzed____ bull 277 18395 __ 1809 2132 3857Averages____ bullbull ____ bull _- ButTer___ 518 _----- 1800 2200 3960==========17819Cbeltk________ 291 __ bullbull_ 18697 1763 2251 3969

JEANERETTE EXPERIMENTS 1935

Colonized __ 1706 Dec 2 r 1986 [ 3552 7054 ButTer__ 1735 Dec 4 2009 3663 7359 ~~ I~~t~ ~~j

I

Cbeck__ __ 497 fdo 1753 dobulll 1987 3544 7042 Co 290 Plant__ J i

4 Colonized 399 Nov 1 1910 Dec 7 2223 3212 7 140 __ do ____324 bull__ do 1937 2269 324 4 Cbeck____ bull 263 ___ do 1979 __ do 1978 3173 0 ZiG 41 Buffer 322i

7 IColonizedbullbull 296 Oct IS 1305 Dec 9 2202 rl66 l091 Co 281 tlrst stubble 7 ButTerbullbullbull__ __ 314 do 1394 Dec 7 9 21S7 2362 ~ 166

305 _do bull __ 1421 Dec 7 2219 2342 5197I~I~~~ 465 Oct 25 1788 Nov IS 2063 2234 4609 S Butrer__ __ 864 __ do 1802 do 1985 2143 4254

8middot Cbeck __ 430 bull __ do 1804 Xov19 2078 1784 3 707

P O J 213 plant 10 Colonized 286 0 t 28 183 0 D I 2163 21 75 4 704 10 Butrer __ __ 4 99 _~~ 170 0 _bullbull~lt j 211 0 23 71 5 002

10 Check 296 do bull__bull 1665 do ____ 2245 2478 5563 C13 Colonlzed__ bull 274 Nov 5 1857 Dec 23 2138 3736 7987

Co 290 first stubble__ el3 Buffer __bull 456 do 1804 Dee 21 I 2163 3724 8055cl3 Check _____ 280 do 1767 bullbulldo 2064 4178 8623 14 Colonized 299 Oct 15 1487 Dec 24 1993 2543 5068

Co 281 tlrststubble 14 IBuffer 301 do _ 1508 Dee 23241 2fJbull 2410 4926 14 Check 3091 bull do 1513 Dec231941 22S9 4385 fC19 1 Colonized 273Xov 4 2059 Dec 26 2288 2526 5 7i9

Co 281 second stubble cI9 I ButTer 810 bulldo bullbull 1961 __ do 2213 2L~7 5880 I el9 Cbeek __ 273 j do 1902 bullbulllo __ 1 22f)3 27S9 6312

C2O Colonized 294 Xov 5 1-~3 DecIi 1gt46 2fi 48 4SIl-S Co2SItlrststubble 1 020 BulTer ~7i do 2006ID(o2728 2091 25m i~51c20 Check bull__ ~ do -~ Dec 27 I~I 2648 ~

COIOniZetL 336 __ ______ mi lO 0 2~ 21 i 5921 Average Jeanerettebullbull ___ BummiddotL____ ) 509 __ bullbull 1~61 __ bullbullbull __ 2119 2791 i Ii 914

I i Check __ 1rlI __ 1148 I 2O~3 2799 5810 Acrage Jeanerette I colonizedJ04 bullbullbullbull __ bull__ bull I~O 2~ __ lii4O2442~

and Houma in 1935 __ ButTer __ 514 __bull ____ 172~ __ __ 1946 i 24M 4799 Check __ 307 __ J8149 bullbullbullbullbull ____ bull 1907 I 2498 4 Ill-

34 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

The yield data on the eleriments of 1934 are tabulated in a form similar to those of 1933 except that the data for the Houma and Jeanshyerette areas are given separately although averaged together It is apparent that in terms of sugar per acre the colonized areas led at Jeanerette in experiments 7 and 9 and at Houma in experiments 4 5 and 10 The check areas led in 1 and 4 at Jeanerette and in 2 3 and 9 at Houma The other experiments gave more sugar per acre in the buffer plots There were five experiments in favor of the colonized areas five in favor of the checks and eight in favor of the buffers In comparing the combined averages it is shown that this year the check plots again surpassed the colonized plots leading by 46 pounds of sugar per acre However the buffers again produced more sugar per acre than either the colonized or the check plots

In 1934 during the rush of the late harvest season the plantation managers failed to notify the Bureau representative that they were harvesting experiment 5 at Jeanerette and consequently weights of the cane and sugar on these plots were not obtained The indications were that these might have been in favor of the colonized area Jeanerette experiment 6 was cut for seed cane and weights were not obtained on this area There would likely have been little difference between the check and colonized areas in this experiment In harshyvesting Jeanerette expcriment 7 the colonized area was harvested on December 12 and 13 and hauled on December 13 and 14 whereas the buffer and check plots were not cut until December 17 and 18 and were hauled on December 19 Since there was a killing freeze on December 11 the delay in harvesting no doubt caused a reduction in sugar per ton of cane and possibly in weight from the buffer and check plots since the stalks were cut lower at the tops to avoid harvesting sour cane A comparison of the gain in sugar in the various plots between the time of the small-mill analyses and the factory analyses indicated that thcre was a loss in sucrose on account of the delay

In 1934 Houma experiments 1 and 2 were harvested after the freeze of December 11 and there was no doubt a reduction in sugar per ton as the yield-data table shows that there was less sugar at the time the factory samples were taken than at the time of the smallshymill samples in contrast to practically all the other experiments In experiment 1 all the cane was windrowed prior to the freeze and should have suffered little deterioration Furthermore all this cane was milled within 2 days and should have been comparable In exshyperiment 2 a part of the colonized plot was harvested last which may have been disadvantageous It is thought however that the data from these two e-periments are reliable enough to show that there had been no advantage in releasing the parasites These two experishyments were carried on in cooperation with the Louisiana Agricultural Experiment Station

In 1935 on the bnsis of sugnr prr ncrr the colonized area led in four exppriments the bufier in four experiments and thr check in six experiments In the remaining six experiments the yields of two or more of the areas were practically equal

Four experiments were windrowed in 1935 Experiment 20 was windrowed on November 22 and 24 and harvested on December 27 and 28 Experiments 7 and 14 were windrowed on November 25 and 27 and on December 6 the cane caught on fire All the cane in

35 EXPERnlEXTS lWR CONTROL OX SUGARCAXE BORER

experiment 7 except 7-P cut 1 was burned In experiment 14 only 14-0 cut I and a part of 14-0 cut 2 were burned This burnt cane was topped in the next 2 days and hauled The sucrose test on the cane in 7-P cut 1 could not be used as this cane was harvested 20 days after the burned cane In experiment 14 only the test made on the unburned cane was used Experiment 24 was windrowed on December 5 and harvested on January 8 Except where there was a time difference in harvesting windrowing apparently did not affect the reliability of the experiments

Explanations should be made concerning experiments 7 8 and 14 of 1935 in the Jeanerette area in which the yields of the colonized areas exceeded the checks by 3 to 4X tons of cane per acre Experishyment 14 was included in the burned area In 1934 7-P had been the check plot and that year it produced nearly IX tons of cane per acre more than the colonized plot The various cuts used in experishyment 8 were supposed according to the overseer to have been comshyparable from past yields bllt at the end of the season both the manager and overseer of the plantation remembered that the two cuts used Cor the check always gave a little less tonnage The sugar per ton of cane was higher in the check since the cane was more mature than in the colonized area but not enough more to offset the increase in tonnage of cane produced in the colonized area

In experiment c13 in 00 290 first-year stubble there was unshydoubtedly a soil difference or some other factor not connected with borer damage that caused the yield in the check to be so much higher than that in the buffer or colonized areas

The factory sucrose test on the colonized area of experiment 20 (Jeanerette 1935) appears to be lower than it should have been In this experimen t the loads for the sucrose test from the buffer and check areas were milled during the afternoon and six test loads from the colonized area were set aside to be run through the following mornshying but the truck driver failed to [ret a sucrose test on them Addishytional test loads were taken the next morning but 8S there had been a heavy rain the night before the cane was wet and muddy This condition probably caused a decrease in the sucrose when the juice was analyzed

In the experiments connucted cooperatively with the Louisiana Agricultural Experiment Station in 1935 the pounds of sugar per acre was highest in the colonized area in one experiment in the buffer in one and in the check area in two experiments The remaining three experiments showed two or more of the areas practically even in sugar per acre Five of the seven cooperative experiments had a borer infestation of over 20 percent of the joints bored in one of the plots and another experiment had an infestation of 187 percent in one of the plots The cooperative experiments showed results no more in favor of the colonized areas than did the other experiments conducted during the three seasons

Differences in yields occur normally between the most nearly unishyform areas obtainable and would be expected if no treatment had been gin)fl any of the plots No relationship was evident however beshytween Trichogramma releases and increased vields j yet such a relationshyship certainly should have appeared in the large number of experishyments conducted had this practice resulted in any significant increase in yield

36 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

YIELD AND SUCROSE VARIATION WITHIN CERTAIN FIELDS

In some of the experiments there was a greater difference in yield between the two or three cuts composing the colonized plot than there was between the average of the colonized and the average of the check cuts of the same experiment For instance in 1934 in an e~periment in the Houma area (table 17) there was a difference of 1308 pounds of sugar per acre between the highest and lowest yields of the three cuts composing the colonized plot There was a differshyence of 1166 pounds between the highest and lowest yields of the cuts of the buffer plot and in the check a difference of 77 pounds between the highest and lo-est cuts Yet there was a difference of only 49 pounds between the average yield of the colonized plot and the average yield of the check plot The great increase in yield per acre in both the high-yielding cut in the colonized plot and the high-yielding cut in the buffer over the other cuts in the same plots was due in both instances to a slightly higher yield of cane per acre and a considerably higher sucrose analysis of the cane This shows very clearly the adshyvantage of taking the yield for each cut and also a separate sucrose analysis from each cut and averaging the results from all the cuts in each plot rather than to depend upon one analysis for the entire plot which might consist of two or three cuts As has been stated this method was followed in all the experiments in 1934 and 1935

TABLE 17-Variation in yield by Cllts in a Trichogramma ezperimclIl plot at Houma La 1984

I IYield ~~ sugar

Plot treatment Cut Size of Cane per i__--___ No cut aere

ron of Acrecane ---------------1--------------

ACT Tona Pound Pound

Colonized ~ i~~ ~~ci i~~~ 3~i 3 1660 2625 16646 4370

Ierage ~ll3SI5~

I l513 I Z7~ 61 Ii WI 26 4452 Buffer 2 2 113 I 2580 13921 3592 3 1 882 2460 13357 32S6

Aerage1 2600 I 144 COS 3762

II7521 24731 141561 3508Cbeck 2 L 600 l06 15 00 3482 3 1 727 2~ 70 144 10 3 559

erage I----i-ii16iH565l~

To determine the variation in cunefields that were considered as nearly uniform as could be obtained heap-row records were taken in certain fields in 1934 Yhen the (une was harYested the (ane from three to five adjoining rows was piled together in one continuous heap row A record was kept of the weight of cane in puCh hpap row and a sugar analysis was obtained for euch (ut in four experiments in the Houma area The yuriation in the number of pounds of sugar per acre obtained per heap row for each cut in three of these experiments

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 37

is shown in figure 4 The variation within each cut is due entirely to cane tonnage per acre as only one analysis for sugar was obtained per cut

EXPERIMENT 2 POJ 234 PLANT CANE 3400

3000

2600

2200

1800

1400

1000 COLONIZED PLOT BUFFER CHECK PLOT

CJ) EXPERIMENT 3 P O J 213 FIRST STUBBLE 0 4200 z I 3800 0 0 3400-

w 3000 a () 2600 ltt

2200a 0 w

1800

a 1400 ltt C) 1000I CJ) COLONIZED PLOT BUFFER CHECK PLOT

EXPERIMENT 4 POJ 213 SECOND STUBBLE 3000

2600

2200

1800

I I I II I1400

1000 I II II II I COLONIZED PLOT BUFFER CHECK PLOT

FIGURE 4-Pounds of sugar per acre in the various heap rows for each cut in the colonized (parasite) buffer and check plots in three experiments in 1934 Each vertical bar represents the yield of a heap row

A record of the weight of cane on each heap row in six experiments was obtained in 1935 and from these weights the sugar per beap row was calculated by using the sucrose analyses for the cut in which the heap row occurred These data are given in table 18

38 TEOHNIOAL BULLETIN 743 U ii DEPT OF AGRIOULTURE

TABLE IS-Yield of 8ugar per acre from individual heap rows in six experiment at Houma La 1985

Heap Experiment Experiment Experiment Experiment Experiment Experiment Plot treatment Cut 22 P O J 23 C P c30 C P c31 Co c32 Co c33 CoNo row 234 stubble 807 stubble 807 stubble 281 stubble 281 stubble 281 stubble

Pound Pound Pound8 Pound8 ______ pou3~~8 poupound~o 4461 3934 3793 3Ii08b______ 3430 2821 4842 3544 3364 3261c______ 3M4 2813 3826 4364 3956 3980 1 d______ 3277 2 l63 3715 3749 2991

4111t= ______~~~_ ~~g______ ____________ 3315 _______________________________________________ _ ~ Colonlied_____ 2Ia~_~--_---_---_---_---_-- ------3~2~4r9~- ------~~- ------~~- bull _ ____________ ____________ 4119 _______________________ _

____________ ____________ 3716 _______________________ _ d______ 3011 ____________ ____________ 5075 _______________________ _

e______ 3110 ___________________________________________________________ _

11______ 3354 3470 4815 4533 3261 3708 b______ 3996 3210 4336 4325 3364 4445c______ 3360 3616 3920 4366 4225 3795

3245 4128 48861~ ------~~~- 3407

______ 3110 3928 4193 4619 4180 4407 b______ 3119 S056 4066 4784 2739 3774 c______ 3386 3679 4272 4227 3418 3400Butter________ _ 2 d______ 3048 3253 ____________ ____________ 3624 3970e______ ____________ 3679 _______________________________________________ _~ == ~~ -~~ ~ ~ ~=1

3 b____ 3127 ------______ 3794 2 799 3 586 1___________ _c______ 3113 ____________ 38tO 2538 4022 ___________ _ 1

d______ 3223 ____________ ____________ 3863 3959 __________ __

s ----- 2828 3463 4230 3412 3147 4134b- 3043 3335 3668 4345 2 98-l 4200

1 c 3347 ____________ 4464 3396 3617 3916I~ ~m ______~~~_______ ~~_______ ~~_I 11______ 2545 3 267 ------------ ------------ 3536__________ __b______ 3029 2807 ____________ ____________ 2879 __________ __Ob -------1 2 c______ 2732 3399 ____________ ____________ 5272 ___________ _

1~ ------~- 1~ r

In 1935 a sucrose analysis was made of the cane from each railroad car from three cuts at Reserve Plantation All the cane in each cut received the same treatment in cultivation colonization and harshyvesting All the cane was hauled without delay and sucrose analyses were all made on the same date Table 19 shows a difference of 1895 pounds of sugar per ton of cane between the highest and the lowest test car in experiment c3O-0 cut 1 jof 1527 pounds in c3Q-B cut 1 and of 1568 in c3O-B cut 2 From this it may be seen that there is considerable difference in the yield of sugar per ton of cane from different carloads from the same cut Thus the difference between small samples can be expected to vary as much if not more If 3 or 4 carloads were used for a c8mposite sample for each cut this error or variation in sampling wou1d be reduced

39 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

TABLE 19-Re8uit8 of 8ucr08e analY8es made on individual carloads of C P 807 first stubble cane at Reserve La Oct 29 1935

Car Weigbtof IYield of00Experiment plot No and cut No cane t~~~Je

Pouooa Poundl 114 12200 16887 141 11800 IM72 183 12040 16072 121 11320 1M 52 152 10360 1M 94

c30-C cut L 109 8400 14821 139 13880 16803 105 11920 16845 82 11580 10025 13 7620 15383 81 2180 161IG

erage 15715

10980 162M 13laquo0 1M 09 13120 162011 13120 15215

-B m Lbull ( ~ 11180 14727 13460 IMM 12940 15217 12980 15111 5240 14934

verage 1M 04

2Z1 13 460 1M 22

c30-B cut 2 ~ Itll lijj1

Average ==1-------1---1-68-g-S

SUMMARY OF EXPERH1ENTS CONDUCTED IN COOPERATION WITH THE LOUISiANA AGRICULTURAL EXPERUIENl STATION

During 1934 only two cooperative experiments were carried on with the Louisiana Agricultural Experiment Station but in 1935 the numshyber was increased to seven The fields for all the cooperative experishyments were selected jointly with a representative of the experiment station and with the assistance of A M ONeal associate soil techshynologist of the Bureau of Plant Industry and officials of the sugar companies on whose properties the experiments were conducted These fields were selected with the greatest possible care to get the areas most comparable as to soil type fertility stand size of cane and past treatment The parasites were furnished by both cooperashytors and released at a time agreeable to both The egg examinations and infestation counts were made both jointly and independently by both cooperatGTS A representative of one or both was present at the time the experiments were harvested to obtan yield data

In 1934 parasites were released in the 2 cooperative experiments during June at the rate of 11950 per acre in c1 and 9241 per ccre in c2 During June July and August a total of 17930 parasites were released per acre in c1 and 18700 parasites were released per acre in c2

Collections of borer eggs were made in both cooperative experiments during April June July August and September The first parshyasitized eggs found in the cooperative experiments were collected

40 TEOHNICAL BULLETIN 743 U S DEPT m~ AGRICULTURE

from the check in c1 on June 26 The final percentage of parasitizashytion averaged only slightly higher in the colonized plots than in the checks

Infestation counts were made on at least 200 stalks in each of the colonized buffer and check pl(lts of both experiments The pershycentage of bored joints WfiS somewhat higher in the colonized than in the check plots The infestation counts are given in table 12 As shown in table 15 Trichogramma releases neither increased the pershycentage of milloble stfilks nor decreased the borer infestation in unmilshylable plants in the six cooperative experiments in which these data were obtained

The cane in all three plots of c1 was windrowed and harvested at approximately the sume time In the colonized plot of c1 the yield of sugar per acre WfiS 55 pounds higher than for the check but in the buffer it was more than 100 pounds higher than in the colonized or check plotf In c2 the yield of sugar in the colonized plot wus less thun for the buffer or check plots of the same experiment (table 16)

Parasites were released in 3 of the cooperative experiments during June 1935 at lL rute higher thfin 5000 per acre The number of parasites relefised in all seven during June July and August ayeraged between 15000 und 43000 per acre The information on the pfirasite releases is given in table 7

ThG percentage of parasitizfition in the colonized plots of c13 e19 and c20 did not average so high during July as in the buflers and checks Late in August and during September the parositization in the colonized buffer and check plots was about the same In the four other cooperatiy( experiments parasitized eggs were found during the latter part of July in the plot intended to be used as the check of c30 where the averngc parnsitization WfiS 217 percent nnd in the plot to be colonized find the buffer plot in c31 where it was 261 and 581 percent respectively before any releases were made No parasitization wns found during July in c32 or c33 During the latter part of August find in September the pamsitization in these four experiments averuged about the same

The percentage of bored joints in c13 c19 and c20 where parasites were released in June averaged about the same for the colonized buffer and check plots In the four experiments where the releases were made during August the percentage of bored joints was about the same in two experiments and slightly in favor of the colonized in one experiment and in the check in the other The data on the infestation counts are given in table 12

The yield of sugar per acre in the three experiments where the parashysites were released in June was slightly higher in the checks than in the colonized plots In the four that received the parasites in August the yield of sugar was about the same in two slightly in favor of the colonized in one and considerably in favor of the check plot in the other The yipld data al( given in table 16

The results of the cooperative experiments do not show any conshysistent gain in favor of the colonized plots The percentage of parasitization number of bored joints and yield of sugar per acre averaged about the same for the nine experiments that were conducted during 1934 and 1935

41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

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i

J

l I t

0

t

r r

~

tshy -1 i

11 j

I I

L

35 EXPERnlEXTS lWR CONTROL OX SUGARCAXE BORER

experiment 7 except 7-P cut 1 was burned In experiment 14 only 14-0 cut I and a part of 14-0 cut 2 were burned This burnt cane was topped in the next 2 days and hauled The sucrose test on the cane in 7-P cut 1 could not be used as this cane was harvested 20 days after the burned cane In experiment 14 only the test made on the unburned cane was used Experiment 24 was windrowed on December 5 and harvested on January 8 Except where there was a time difference in harvesting windrowing apparently did not affect the reliability of the experiments

Explanations should be made concerning experiments 7 8 and 14 of 1935 in the Jeanerette area in which the yields of the colonized areas exceeded the checks by 3 to 4X tons of cane per acre Experishyment 14 was included in the burned area In 1934 7-P had been the check plot and that year it produced nearly IX tons of cane per acre more than the colonized plot The various cuts used in experishyment 8 were supposed according to the overseer to have been comshyparable from past yields bllt at the end of the season both the manager and overseer of the plantation remembered that the two cuts used Cor the check always gave a little less tonnage The sugar per ton of cane was higher in the check since the cane was more mature than in the colonized area but not enough more to offset the increase in tonnage of cane produced in the colonized area

In experiment c13 in 00 290 first-year stubble there was unshydoubtedly a soil difference or some other factor not connected with borer damage that caused the yield in the check to be so much higher than that in the buffer or colonized areas

The factory sucrose test on the colonized area of experiment 20 (Jeanerette 1935) appears to be lower than it should have been In this experimen t the loads for the sucrose test from the buffer and check areas were milled during the afternoon and six test loads from the colonized area were set aside to be run through the following mornshying but the truck driver failed to [ret a sucrose test on them Addishytional test loads were taken the next morning but 8S there had been a heavy rain the night before the cane was wet and muddy This condition probably caused a decrease in the sucrose when the juice was analyzed

In the experiments connucted cooperatively with the Louisiana Agricultural Experiment Station in 1935 the pounds of sugar per acre was highest in the colonized area in one experiment in the buffer in one and in the check area in two experiments The remaining three experiments showed two or more of the areas practically even in sugar per acre Five of the seven cooperative experiments had a borer infestation of over 20 percent of the joints bored in one of the plots and another experiment had an infestation of 187 percent in one of the plots The cooperative experiments showed results no more in favor of the colonized areas than did the other experiments conducted during the three seasons

Differences in yields occur normally between the most nearly unishyform areas obtainable and would be expected if no treatment had been gin)fl any of the plots No relationship was evident however beshytween Trichogramma releases and increased vields j yet such a relationshyship certainly should have appeared in the large number of experishyments conducted had this practice resulted in any significant increase in yield

36 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

YIELD AND SUCROSE VARIATION WITHIN CERTAIN FIELDS

In some of the experiments there was a greater difference in yield between the two or three cuts composing the colonized plot than there was between the average of the colonized and the average of the check cuts of the same experiment For instance in 1934 in an e~periment in the Houma area (table 17) there was a difference of 1308 pounds of sugar per acre between the highest and lowest yields of the three cuts composing the colonized plot There was a differshyence of 1166 pounds between the highest and lowest yields of the cuts of the buffer plot and in the check a difference of 77 pounds between the highest and lo-est cuts Yet there was a difference of only 49 pounds between the average yield of the colonized plot and the average yield of the check plot The great increase in yield per acre in both the high-yielding cut in the colonized plot and the high-yielding cut in the buffer over the other cuts in the same plots was due in both instances to a slightly higher yield of cane per acre and a considerably higher sucrose analysis of the cane This shows very clearly the adshyvantage of taking the yield for each cut and also a separate sucrose analysis from each cut and averaging the results from all the cuts in each plot rather than to depend upon one analysis for the entire plot which might consist of two or three cuts As has been stated this method was followed in all the experiments in 1934 and 1935

TABLE 17-Variation in yield by Cllts in a Trichogramma ezperimclIl plot at Houma La 1984

I IYield ~~ sugar

Plot treatment Cut Size of Cane per i__--___ No cut aere

ron of Acrecane ---------------1--------------

ACT Tona Pound Pound

Colonized ~ i~~ ~~ci i~~~ 3~i 3 1660 2625 16646 4370

Ierage ~ll3SI5~

I l513 I Z7~ 61 Ii WI 26 4452 Buffer 2 2 113 I 2580 13921 3592 3 1 882 2460 13357 32S6

Aerage1 2600 I 144 COS 3762

II7521 24731 141561 3508Cbeck 2 L 600 l06 15 00 3482 3 1 727 2~ 70 144 10 3 559

erage I----i-ii16iH565l~

To determine the variation in cunefields that were considered as nearly uniform as could be obtained heap-row records were taken in certain fields in 1934 Yhen the (une was harYested the (ane from three to five adjoining rows was piled together in one continuous heap row A record was kept of the weight of cane in puCh hpap row and a sugar analysis was obtained for euch (ut in four experiments in the Houma area The yuriation in the number of pounds of sugar per acre obtained per heap row for each cut in three of these experiments

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 37

is shown in figure 4 The variation within each cut is due entirely to cane tonnage per acre as only one analysis for sugar was obtained per cut

EXPERIMENT 2 POJ 234 PLANT CANE 3400

3000

2600

2200

1800

1400

1000 COLONIZED PLOT BUFFER CHECK PLOT

CJ) EXPERIMENT 3 P O J 213 FIRST STUBBLE 0 4200 z I 3800 0 0 3400-

w 3000 a () 2600 ltt

2200a 0 w

1800

a 1400 ltt C) 1000I CJ) COLONIZED PLOT BUFFER CHECK PLOT

EXPERIMENT 4 POJ 213 SECOND STUBBLE 3000

2600

2200

1800

I I I II I1400

1000 I II II II I COLONIZED PLOT BUFFER CHECK PLOT

FIGURE 4-Pounds of sugar per acre in the various heap rows for each cut in the colonized (parasite) buffer and check plots in three experiments in 1934 Each vertical bar represents the yield of a heap row

A record of the weight of cane on each heap row in six experiments was obtained in 1935 and from these weights the sugar per beap row was calculated by using the sucrose analyses for the cut in which the heap row occurred These data are given in table 18

38 TEOHNIOAL BULLETIN 743 U ii DEPT OF AGRIOULTURE

TABLE IS-Yield of 8ugar per acre from individual heap rows in six experiment at Houma La 1985

Heap Experiment Experiment Experiment Experiment Experiment Experiment Plot treatment Cut 22 P O J 23 C P c30 C P c31 Co c32 Co c33 CoNo row 234 stubble 807 stubble 807 stubble 281 stubble 281 stubble 281 stubble

Pound Pound Pound8 Pound8 ______ pou3~~8 poupound~o 4461 3934 3793 3Ii08b______ 3430 2821 4842 3544 3364 3261c______ 3M4 2813 3826 4364 3956 3980 1 d______ 3277 2 l63 3715 3749 2991

4111t= ______~~~_ ~~g______ ____________ 3315 _______________________________________________ _ ~ Colonlied_____ 2Ia~_~--_---_---_---_---_-- ------3~2~4r9~- ------~~- ------~~- bull _ ____________ ____________ 4119 _______________________ _

____________ ____________ 3716 _______________________ _ d______ 3011 ____________ ____________ 5075 _______________________ _

e______ 3110 ___________________________________________________________ _

11______ 3354 3470 4815 4533 3261 3708 b______ 3996 3210 4336 4325 3364 4445c______ 3360 3616 3920 4366 4225 3795

3245 4128 48861~ ------~~~- 3407

______ 3110 3928 4193 4619 4180 4407 b______ 3119 S056 4066 4784 2739 3774 c______ 3386 3679 4272 4227 3418 3400Butter________ _ 2 d______ 3048 3253 ____________ ____________ 3624 3970e______ ____________ 3679 _______________________________________________ _~ == ~~ -~~ ~ ~ ~=1

3 b____ 3127 ------______ 3794 2 799 3 586 1___________ _c______ 3113 ____________ 38tO 2538 4022 ___________ _ 1

d______ 3223 ____________ ____________ 3863 3959 __________ __

s ----- 2828 3463 4230 3412 3147 4134b- 3043 3335 3668 4345 2 98-l 4200

1 c 3347 ____________ 4464 3396 3617 3916I~ ~m ______~~~_______ ~~_______ ~~_I 11______ 2545 3 267 ------------ ------------ 3536__________ __b______ 3029 2807 ____________ ____________ 2879 __________ __Ob -------1 2 c______ 2732 3399 ____________ ____________ 5272 ___________ _

1~ ------~- 1~ r

In 1935 a sucrose analysis was made of the cane from each railroad car from three cuts at Reserve Plantation All the cane in each cut received the same treatment in cultivation colonization and harshyvesting All the cane was hauled without delay and sucrose analyses were all made on the same date Table 19 shows a difference of 1895 pounds of sugar per ton of cane between the highest and the lowest test car in experiment c3O-0 cut 1 jof 1527 pounds in c3Q-B cut 1 and of 1568 in c3O-B cut 2 From this it may be seen that there is considerable difference in the yield of sugar per ton of cane from different carloads from the same cut Thus the difference between small samples can be expected to vary as much if not more If 3 or 4 carloads were used for a c8mposite sample for each cut this error or variation in sampling wou1d be reduced

39 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

TABLE 19-Re8uit8 of 8ucr08e analY8es made on individual carloads of C P 807 first stubble cane at Reserve La Oct 29 1935

Car Weigbtof IYield of00Experiment plot No and cut No cane t~~~Je

Pouooa Poundl 114 12200 16887 141 11800 IM72 183 12040 16072 121 11320 1M 52 152 10360 1M 94

c30-C cut L 109 8400 14821 139 13880 16803 105 11920 16845 82 11580 10025 13 7620 15383 81 2180 161IG

erage 15715

10980 162M 13laquo0 1M 09 13120 162011 13120 15215

-B m Lbull ( ~ 11180 14727 13460 IMM 12940 15217 12980 15111 5240 14934

verage 1M 04

2Z1 13 460 1M 22

c30-B cut 2 ~ Itll lijj1

Average ==1-------1---1-68-g-S

SUMMARY OF EXPERH1ENTS CONDUCTED IN COOPERATION WITH THE LOUISiANA AGRICULTURAL EXPERUIENl STATION

During 1934 only two cooperative experiments were carried on with the Louisiana Agricultural Experiment Station but in 1935 the numshyber was increased to seven The fields for all the cooperative experishyments were selected jointly with a representative of the experiment station and with the assistance of A M ONeal associate soil techshynologist of the Bureau of Plant Industry and officials of the sugar companies on whose properties the experiments were conducted These fields were selected with the greatest possible care to get the areas most comparable as to soil type fertility stand size of cane and past treatment The parasites were furnished by both cooperashytors and released at a time agreeable to both The egg examinations and infestation counts were made both jointly and independently by both cooperatGTS A representative of one or both was present at the time the experiments were harvested to obtan yield data

In 1934 parasites were released in the 2 cooperative experiments during June at the rate of 11950 per acre in c1 and 9241 per ccre in c2 During June July and August a total of 17930 parasites were released per acre in c1 and 18700 parasites were released per acre in c2

Collections of borer eggs were made in both cooperative experiments during April June July August and September The first parshyasitized eggs found in the cooperative experiments were collected

40 TEOHNICAL BULLETIN 743 U S DEPT m~ AGRICULTURE

from the check in c1 on June 26 The final percentage of parasitizashytion averaged only slightly higher in the colonized plots than in the checks

Infestation counts were made on at least 200 stalks in each of the colonized buffer and check pl(lts of both experiments The pershycentage of bored joints WfiS somewhat higher in the colonized than in the check plots The infestation counts are given in table 12 As shown in table 15 Trichogramma releases neither increased the pershycentage of milloble stfilks nor decreased the borer infestation in unmilshylable plants in the six cooperative experiments in which these data were obtained

The cane in all three plots of c1 was windrowed and harvested at approximately the sume time In the colonized plot of c1 the yield of sugar per acre WfiS 55 pounds higher than for the check but in the buffer it was more than 100 pounds higher than in the colonized or check plotf In c2 the yield of sugar in the colonized plot wus less thun for the buffer or check plots of the same experiment (table 16)

Parasites were released in 3 of the cooperative experiments during June 1935 at lL rute higher thfin 5000 per acre The number of parasites relefised in all seven during June July and August ayeraged between 15000 und 43000 per acre The information on the pfirasite releases is given in table 7

ThG percentage of parasitizfition in the colonized plots of c13 e19 and c20 did not average so high during July as in the buflers and checks Late in August and during September the parositization in the colonized buffer and check plots was about the same In the four other cooperatiy( experiments parasitized eggs were found during the latter part of July in the plot intended to be used as the check of c30 where the averngc parnsitization WfiS 217 percent nnd in the plot to be colonized find the buffer plot in c31 where it was 261 and 581 percent respectively before any releases were made No parasitization wns found during July in c32 or c33 During the latter part of August find in September the pamsitization in these four experiments averuged about the same

The percentage of bored joints in c13 c19 and c20 where parasites were released in June averaged about the same for the colonized buffer and check plots In the four experiments where the releases were made during August the percentage of bored joints was about the same in two experiments and slightly in favor of the colonized in one experiment and in the check in the other The data on the infestation counts are given in table 12

The yield of sugar per acre in the three experiments where the parashysites were released in June was slightly higher in the checks than in the colonized plots In the four that received the parasites in August the yield of sugar was about the same in two slightly in favor of the colonized in one and considerably in favor of the check plot in the other The yipld data al( given in table 16

The results of the cooperative experiments do not show any conshysistent gain in favor of the colonized plots The percentage of parasitization number of bored joints and yield of sugar per acre averaged about the same for the nine experiments that were conducted during 1934 and 1935

41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

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0

t

r r

~

tshy -1 i

11 j

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36 TECHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

YIELD AND SUCROSE VARIATION WITHIN CERTAIN FIELDS

In some of the experiments there was a greater difference in yield between the two or three cuts composing the colonized plot than there was between the average of the colonized and the average of the check cuts of the same experiment For instance in 1934 in an e~periment in the Houma area (table 17) there was a difference of 1308 pounds of sugar per acre between the highest and lowest yields of the three cuts composing the colonized plot There was a differshyence of 1166 pounds between the highest and lowest yields of the cuts of the buffer plot and in the check a difference of 77 pounds between the highest and lo-est cuts Yet there was a difference of only 49 pounds between the average yield of the colonized plot and the average yield of the check plot The great increase in yield per acre in both the high-yielding cut in the colonized plot and the high-yielding cut in the buffer over the other cuts in the same plots was due in both instances to a slightly higher yield of cane per acre and a considerably higher sucrose analysis of the cane This shows very clearly the adshyvantage of taking the yield for each cut and also a separate sucrose analysis from each cut and averaging the results from all the cuts in each plot rather than to depend upon one analysis for the entire plot which might consist of two or three cuts As has been stated this method was followed in all the experiments in 1934 and 1935

TABLE 17-Variation in yield by Cllts in a Trichogramma ezperimclIl plot at Houma La 1984

I IYield ~~ sugar

Plot treatment Cut Size of Cane per i__--___ No cut aere

ron of Acrecane ---------------1--------------

ACT Tona Pound Pound

Colonized ~ i~~ ~~ci i~~~ 3~i 3 1660 2625 16646 4370

Ierage ~ll3SI5~

I l513 I Z7~ 61 Ii WI 26 4452 Buffer 2 2 113 I 2580 13921 3592 3 1 882 2460 13357 32S6

Aerage1 2600 I 144 COS 3762

II7521 24731 141561 3508Cbeck 2 L 600 l06 15 00 3482 3 1 727 2~ 70 144 10 3 559

erage I----i-ii16iH565l~

To determine the variation in cunefields that were considered as nearly uniform as could be obtained heap-row records were taken in certain fields in 1934 Yhen the (une was harYested the (ane from three to five adjoining rows was piled together in one continuous heap row A record was kept of the weight of cane in puCh hpap row and a sugar analysis was obtained for euch (ut in four experiments in the Houma area The yuriation in the number of pounds of sugar per acre obtained per heap row for each cut in three of these experiments

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 37

is shown in figure 4 The variation within each cut is due entirely to cane tonnage per acre as only one analysis for sugar was obtained per cut

EXPERIMENT 2 POJ 234 PLANT CANE 3400

3000

2600

2200

1800

1400

1000 COLONIZED PLOT BUFFER CHECK PLOT

CJ) EXPERIMENT 3 P O J 213 FIRST STUBBLE 0 4200 z I 3800 0 0 3400-

w 3000 a () 2600 ltt

2200a 0 w

1800

a 1400 ltt C) 1000I CJ) COLONIZED PLOT BUFFER CHECK PLOT

EXPERIMENT 4 POJ 213 SECOND STUBBLE 3000

2600

2200

1800

I I I II I1400

1000 I II II II I COLONIZED PLOT BUFFER CHECK PLOT

FIGURE 4-Pounds of sugar per acre in the various heap rows for each cut in the colonized (parasite) buffer and check plots in three experiments in 1934 Each vertical bar represents the yield of a heap row

A record of the weight of cane on each heap row in six experiments was obtained in 1935 and from these weights the sugar per beap row was calculated by using the sucrose analyses for the cut in which the heap row occurred These data are given in table 18

38 TEOHNIOAL BULLETIN 743 U ii DEPT OF AGRIOULTURE

TABLE IS-Yield of 8ugar per acre from individual heap rows in six experiment at Houma La 1985

Heap Experiment Experiment Experiment Experiment Experiment Experiment Plot treatment Cut 22 P O J 23 C P c30 C P c31 Co c32 Co c33 CoNo row 234 stubble 807 stubble 807 stubble 281 stubble 281 stubble 281 stubble

Pound Pound Pound8 Pound8 ______ pou3~~8 poupound~o 4461 3934 3793 3Ii08b______ 3430 2821 4842 3544 3364 3261c______ 3M4 2813 3826 4364 3956 3980 1 d______ 3277 2 l63 3715 3749 2991

4111t= ______~~~_ ~~g______ ____________ 3315 _______________________________________________ _ ~ Colonlied_____ 2Ia~_~--_---_---_---_---_-- ------3~2~4r9~- ------~~- ------~~- bull _ ____________ ____________ 4119 _______________________ _

____________ ____________ 3716 _______________________ _ d______ 3011 ____________ ____________ 5075 _______________________ _

e______ 3110 ___________________________________________________________ _

11______ 3354 3470 4815 4533 3261 3708 b______ 3996 3210 4336 4325 3364 4445c______ 3360 3616 3920 4366 4225 3795

3245 4128 48861~ ------~~~- 3407

______ 3110 3928 4193 4619 4180 4407 b______ 3119 S056 4066 4784 2739 3774 c______ 3386 3679 4272 4227 3418 3400Butter________ _ 2 d______ 3048 3253 ____________ ____________ 3624 3970e______ ____________ 3679 _______________________________________________ _~ == ~~ -~~ ~ ~ ~=1

3 b____ 3127 ------______ 3794 2 799 3 586 1___________ _c______ 3113 ____________ 38tO 2538 4022 ___________ _ 1

d______ 3223 ____________ ____________ 3863 3959 __________ __

s ----- 2828 3463 4230 3412 3147 4134b- 3043 3335 3668 4345 2 98-l 4200

1 c 3347 ____________ 4464 3396 3617 3916I~ ~m ______~~~_______ ~~_______ ~~_I 11______ 2545 3 267 ------------ ------------ 3536__________ __b______ 3029 2807 ____________ ____________ 2879 __________ __Ob -------1 2 c______ 2732 3399 ____________ ____________ 5272 ___________ _

1~ ------~- 1~ r

In 1935 a sucrose analysis was made of the cane from each railroad car from three cuts at Reserve Plantation All the cane in each cut received the same treatment in cultivation colonization and harshyvesting All the cane was hauled without delay and sucrose analyses were all made on the same date Table 19 shows a difference of 1895 pounds of sugar per ton of cane between the highest and the lowest test car in experiment c3O-0 cut 1 jof 1527 pounds in c3Q-B cut 1 and of 1568 in c3O-B cut 2 From this it may be seen that there is considerable difference in the yield of sugar per ton of cane from different carloads from the same cut Thus the difference between small samples can be expected to vary as much if not more If 3 or 4 carloads were used for a c8mposite sample for each cut this error or variation in sampling wou1d be reduced

39 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

TABLE 19-Re8uit8 of 8ucr08e analY8es made on individual carloads of C P 807 first stubble cane at Reserve La Oct 29 1935

Car Weigbtof IYield of00Experiment plot No and cut No cane t~~~Je

Pouooa Poundl 114 12200 16887 141 11800 IM72 183 12040 16072 121 11320 1M 52 152 10360 1M 94

c30-C cut L 109 8400 14821 139 13880 16803 105 11920 16845 82 11580 10025 13 7620 15383 81 2180 161IG

erage 15715

10980 162M 13laquo0 1M 09 13120 162011 13120 15215

-B m Lbull ( ~ 11180 14727 13460 IMM 12940 15217 12980 15111 5240 14934

verage 1M 04

2Z1 13 460 1M 22

c30-B cut 2 ~ Itll lijj1

Average ==1-------1---1-68-g-S

SUMMARY OF EXPERH1ENTS CONDUCTED IN COOPERATION WITH THE LOUISiANA AGRICULTURAL EXPERUIENl STATION

During 1934 only two cooperative experiments were carried on with the Louisiana Agricultural Experiment Station but in 1935 the numshyber was increased to seven The fields for all the cooperative experishyments were selected jointly with a representative of the experiment station and with the assistance of A M ONeal associate soil techshynologist of the Bureau of Plant Industry and officials of the sugar companies on whose properties the experiments were conducted These fields were selected with the greatest possible care to get the areas most comparable as to soil type fertility stand size of cane and past treatment The parasites were furnished by both cooperashytors and released at a time agreeable to both The egg examinations and infestation counts were made both jointly and independently by both cooperatGTS A representative of one or both was present at the time the experiments were harvested to obtan yield data

In 1934 parasites were released in the 2 cooperative experiments during June at the rate of 11950 per acre in c1 and 9241 per ccre in c2 During June July and August a total of 17930 parasites were released per acre in c1 and 18700 parasites were released per acre in c2

Collections of borer eggs were made in both cooperative experiments during April June July August and September The first parshyasitized eggs found in the cooperative experiments were collected

40 TEOHNICAL BULLETIN 743 U S DEPT m~ AGRICULTURE

from the check in c1 on June 26 The final percentage of parasitizashytion averaged only slightly higher in the colonized plots than in the checks

Infestation counts were made on at least 200 stalks in each of the colonized buffer and check pl(lts of both experiments The pershycentage of bored joints WfiS somewhat higher in the colonized than in the check plots The infestation counts are given in table 12 As shown in table 15 Trichogramma releases neither increased the pershycentage of milloble stfilks nor decreased the borer infestation in unmilshylable plants in the six cooperative experiments in which these data were obtained

The cane in all three plots of c1 was windrowed and harvested at approximately the sume time In the colonized plot of c1 the yield of sugar per acre WfiS 55 pounds higher than for the check but in the buffer it was more than 100 pounds higher than in the colonized or check plotf In c2 the yield of sugar in the colonized plot wus less thun for the buffer or check plots of the same experiment (table 16)

Parasites were released in 3 of the cooperative experiments during June 1935 at lL rute higher thfin 5000 per acre The number of parasites relefised in all seven during June July and August ayeraged between 15000 und 43000 per acre The information on the pfirasite releases is given in table 7

ThG percentage of parasitizfition in the colonized plots of c13 e19 and c20 did not average so high during July as in the buflers and checks Late in August and during September the parositization in the colonized buffer and check plots was about the same In the four other cooperatiy( experiments parasitized eggs were found during the latter part of July in the plot intended to be used as the check of c30 where the averngc parnsitization WfiS 217 percent nnd in the plot to be colonized find the buffer plot in c31 where it was 261 and 581 percent respectively before any releases were made No parasitization wns found during July in c32 or c33 During the latter part of August find in September the pamsitization in these four experiments averuged about the same

The percentage of bored joints in c13 c19 and c20 where parasites were released in June averaged about the same for the colonized buffer and check plots In the four experiments where the releases were made during August the percentage of bored joints was about the same in two experiments and slightly in favor of the colonized in one experiment and in the check in the other The data on the infestation counts are given in table 12

The yield of sugar per acre in the three experiments where the parashysites were released in June was slightly higher in the checks than in the colonized plots In the four that received the parasites in August the yield of sugar was about the same in two slightly in favor of the colonized in one and considerably in favor of the check plot in the other The yipld data al( given in table 16

The results of the cooperative experiments do not show any conshysistent gain in favor of the colonized plots The percentage of parasitization number of bored joints and yield of sugar per acre averaged about the same for the nine experiments that were conducted during 1934 and 1935

41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

i

i

J

l I t

0

t

r r

~

tshy -1 i

11 j

I I

L

EXPERIMENTS FOR CONTROL OF SUGARCANE BORER 37

is shown in figure 4 The variation within each cut is due entirely to cane tonnage per acre as only one analysis for sugar was obtained per cut

EXPERIMENT 2 POJ 234 PLANT CANE 3400

3000

2600

2200

1800

1400

1000 COLONIZED PLOT BUFFER CHECK PLOT

CJ) EXPERIMENT 3 P O J 213 FIRST STUBBLE 0 4200 z I 3800 0 0 3400-

w 3000 a () 2600 ltt

2200a 0 w

1800

a 1400 ltt C) 1000I CJ) COLONIZED PLOT BUFFER CHECK PLOT

EXPERIMENT 4 POJ 213 SECOND STUBBLE 3000

2600

2200

1800

I I I II I1400

1000 I II II II I COLONIZED PLOT BUFFER CHECK PLOT

FIGURE 4-Pounds of sugar per acre in the various heap rows for each cut in the colonized (parasite) buffer and check plots in three experiments in 1934 Each vertical bar represents the yield of a heap row

A record of the weight of cane on each heap row in six experiments was obtained in 1935 and from these weights the sugar per beap row was calculated by using the sucrose analyses for the cut in which the heap row occurred These data are given in table 18

38 TEOHNIOAL BULLETIN 743 U ii DEPT OF AGRIOULTURE

TABLE IS-Yield of 8ugar per acre from individual heap rows in six experiment at Houma La 1985

Heap Experiment Experiment Experiment Experiment Experiment Experiment Plot treatment Cut 22 P O J 23 C P c30 C P c31 Co c32 Co c33 CoNo row 234 stubble 807 stubble 807 stubble 281 stubble 281 stubble 281 stubble

Pound Pound Pound8 Pound8 ______ pou3~~8 poupound~o 4461 3934 3793 3Ii08b______ 3430 2821 4842 3544 3364 3261c______ 3M4 2813 3826 4364 3956 3980 1 d______ 3277 2 l63 3715 3749 2991

4111t= ______~~~_ ~~g______ ____________ 3315 _______________________________________________ _ ~ Colonlied_____ 2Ia~_~--_---_---_---_---_-- ------3~2~4r9~- ------~~- ------~~- bull _ ____________ ____________ 4119 _______________________ _

____________ ____________ 3716 _______________________ _ d______ 3011 ____________ ____________ 5075 _______________________ _

e______ 3110 ___________________________________________________________ _

11______ 3354 3470 4815 4533 3261 3708 b______ 3996 3210 4336 4325 3364 4445c______ 3360 3616 3920 4366 4225 3795

3245 4128 48861~ ------~~~- 3407

______ 3110 3928 4193 4619 4180 4407 b______ 3119 S056 4066 4784 2739 3774 c______ 3386 3679 4272 4227 3418 3400Butter________ _ 2 d______ 3048 3253 ____________ ____________ 3624 3970e______ ____________ 3679 _______________________________________________ _~ == ~~ -~~ ~ ~ ~=1

3 b____ 3127 ------______ 3794 2 799 3 586 1___________ _c______ 3113 ____________ 38tO 2538 4022 ___________ _ 1

d______ 3223 ____________ ____________ 3863 3959 __________ __

s ----- 2828 3463 4230 3412 3147 4134b- 3043 3335 3668 4345 2 98-l 4200

1 c 3347 ____________ 4464 3396 3617 3916I~ ~m ______~~~_______ ~~_______ ~~_I 11______ 2545 3 267 ------------ ------------ 3536__________ __b______ 3029 2807 ____________ ____________ 2879 __________ __Ob -------1 2 c______ 2732 3399 ____________ ____________ 5272 ___________ _

1~ ------~- 1~ r

In 1935 a sucrose analysis was made of the cane from each railroad car from three cuts at Reserve Plantation All the cane in each cut received the same treatment in cultivation colonization and harshyvesting All the cane was hauled without delay and sucrose analyses were all made on the same date Table 19 shows a difference of 1895 pounds of sugar per ton of cane between the highest and the lowest test car in experiment c3O-0 cut 1 jof 1527 pounds in c3Q-B cut 1 and of 1568 in c3O-B cut 2 From this it may be seen that there is considerable difference in the yield of sugar per ton of cane from different carloads from the same cut Thus the difference between small samples can be expected to vary as much if not more If 3 or 4 carloads were used for a c8mposite sample for each cut this error or variation in sampling wou1d be reduced

39 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

TABLE 19-Re8uit8 of 8ucr08e analY8es made on individual carloads of C P 807 first stubble cane at Reserve La Oct 29 1935

Car Weigbtof IYield of00Experiment plot No and cut No cane t~~~Je

Pouooa Poundl 114 12200 16887 141 11800 IM72 183 12040 16072 121 11320 1M 52 152 10360 1M 94

c30-C cut L 109 8400 14821 139 13880 16803 105 11920 16845 82 11580 10025 13 7620 15383 81 2180 161IG

erage 15715

10980 162M 13laquo0 1M 09 13120 162011 13120 15215

-B m Lbull ( ~ 11180 14727 13460 IMM 12940 15217 12980 15111 5240 14934

verage 1M 04

2Z1 13 460 1M 22

c30-B cut 2 ~ Itll lijj1

Average ==1-------1---1-68-g-S

SUMMARY OF EXPERH1ENTS CONDUCTED IN COOPERATION WITH THE LOUISiANA AGRICULTURAL EXPERUIENl STATION

During 1934 only two cooperative experiments were carried on with the Louisiana Agricultural Experiment Station but in 1935 the numshyber was increased to seven The fields for all the cooperative experishyments were selected jointly with a representative of the experiment station and with the assistance of A M ONeal associate soil techshynologist of the Bureau of Plant Industry and officials of the sugar companies on whose properties the experiments were conducted These fields were selected with the greatest possible care to get the areas most comparable as to soil type fertility stand size of cane and past treatment The parasites were furnished by both cooperashytors and released at a time agreeable to both The egg examinations and infestation counts were made both jointly and independently by both cooperatGTS A representative of one or both was present at the time the experiments were harvested to obtan yield data

In 1934 parasites were released in the 2 cooperative experiments during June at the rate of 11950 per acre in c1 and 9241 per ccre in c2 During June July and August a total of 17930 parasites were released per acre in c1 and 18700 parasites were released per acre in c2

Collections of borer eggs were made in both cooperative experiments during April June July August and September The first parshyasitized eggs found in the cooperative experiments were collected

40 TEOHNICAL BULLETIN 743 U S DEPT m~ AGRICULTURE

from the check in c1 on June 26 The final percentage of parasitizashytion averaged only slightly higher in the colonized plots than in the checks

Infestation counts were made on at least 200 stalks in each of the colonized buffer and check pl(lts of both experiments The pershycentage of bored joints WfiS somewhat higher in the colonized than in the check plots The infestation counts are given in table 12 As shown in table 15 Trichogramma releases neither increased the pershycentage of milloble stfilks nor decreased the borer infestation in unmilshylable plants in the six cooperative experiments in which these data were obtained

The cane in all three plots of c1 was windrowed and harvested at approximately the sume time In the colonized plot of c1 the yield of sugar per acre WfiS 55 pounds higher than for the check but in the buffer it was more than 100 pounds higher than in the colonized or check plotf In c2 the yield of sugar in the colonized plot wus less thun for the buffer or check plots of the same experiment (table 16)

Parasites were released in 3 of the cooperative experiments during June 1935 at lL rute higher thfin 5000 per acre The number of parasites relefised in all seven during June July and August ayeraged between 15000 und 43000 per acre The information on the pfirasite releases is given in table 7

ThG percentage of parasitizfition in the colonized plots of c13 e19 and c20 did not average so high during July as in the buflers and checks Late in August and during September the parositization in the colonized buffer and check plots was about the same In the four other cooperatiy( experiments parasitized eggs were found during the latter part of July in the plot intended to be used as the check of c30 where the averngc parnsitization WfiS 217 percent nnd in the plot to be colonized find the buffer plot in c31 where it was 261 and 581 percent respectively before any releases were made No parasitization wns found during July in c32 or c33 During the latter part of August find in September the pamsitization in these four experiments averuged about the same

The percentage of bored joints in c13 c19 and c20 where parasites were released in June averaged about the same for the colonized buffer and check plots In the four experiments where the releases were made during August the percentage of bored joints was about the same in two experiments and slightly in favor of the colonized in one experiment and in the check in the other The data on the infestation counts are given in table 12

The yield of sugar per acre in the three experiments where the parashysites were released in June was slightly higher in the checks than in the colonized plots In the four that received the parasites in August the yield of sugar was about the same in two slightly in favor of the colonized in one and considerably in favor of the check plot in the other The yipld data al( given in table 16

The results of the cooperative experiments do not show any conshysistent gain in favor of the colonized plots The percentage of parasitization number of bored joints and yield of sugar per acre averaged about the same for the nine experiments that were conducted during 1934 and 1935

41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

i

i

J

l I t

0

t

r r

~

tshy -1 i

11 j

I I

L

38 TEOHNIOAL BULLETIN 743 U ii DEPT OF AGRIOULTURE

TABLE IS-Yield of 8ugar per acre from individual heap rows in six experiment at Houma La 1985

Heap Experiment Experiment Experiment Experiment Experiment Experiment Plot treatment Cut 22 P O J 23 C P c30 C P c31 Co c32 Co c33 CoNo row 234 stubble 807 stubble 807 stubble 281 stubble 281 stubble 281 stubble

Pound Pound Pound8 Pound8 ______ pou3~~8 poupound~o 4461 3934 3793 3Ii08b______ 3430 2821 4842 3544 3364 3261c______ 3M4 2813 3826 4364 3956 3980 1 d______ 3277 2 l63 3715 3749 2991

4111t= ______~~~_ ~~g______ ____________ 3315 _______________________________________________ _ ~ Colonlied_____ 2Ia~_~--_---_---_---_---_-- ------3~2~4r9~- ------~~- ------~~- bull _ ____________ ____________ 4119 _______________________ _

____________ ____________ 3716 _______________________ _ d______ 3011 ____________ ____________ 5075 _______________________ _

e______ 3110 ___________________________________________________________ _

11______ 3354 3470 4815 4533 3261 3708 b______ 3996 3210 4336 4325 3364 4445c______ 3360 3616 3920 4366 4225 3795

3245 4128 48861~ ------~~~- 3407

______ 3110 3928 4193 4619 4180 4407 b______ 3119 S056 4066 4784 2739 3774 c______ 3386 3679 4272 4227 3418 3400Butter________ _ 2 d______ 3048 3253 ____________ ____________ 3624 3970e______ ____________ 3679 _______________________________________________ _~ == ~~ -~~ ~ ~ ~=1

3 b____ 3127 ------______ 3794 2 799 3 586 1___________ _c______ 3113 ____________ 38tO 2538 4022 ___________ _ 1

d______ 3223 ____________ ____________ 3863 3959 __________ __

s ----- 2828 3463 4230 3412 3147 4134b- 3043 3335 3668 4345 2 98-l 4200

1 c 3347 ____________ 4464 3396 3617 3916I~ ~m ______~~~_______ ~~_______ ~~_I 11______ 2545 3 267 ------------ ------------ 3536__________ __b______ 3029 2807 ____________ ____________ 2879 __________ __Ob -------1 2 c______ 2732 3399 ____________ ____________ 5272 ___________ _

1~ ------~- 1~ r

In 1935 a sucrose analysis was made of the cane from each railroad car from three cuts at Reserve Plantation All the cane in each cut received the same treatment in cultivation colonization and harshyvesting All the cane was hauled without delay and sucrose analyses were all made on the same date Table 19 shows a difference of 1895 pounds of sugar per ton of cane between the highest and the lowest test car in experiment c3O-0 cut 1 jof 1527 pounds in c3Q-B cut 1 and of 1568 in c3O-B cut 2 From this it may be seen that there is considerable difference in the yield of sugar per ton of cane from different carloads from the same cut Thus the difference between small samples can be expected to vary as much if not more If 3 or 4 carloads were used for a c8mposite sample for each cut this error or variation in sampling wou1d be reduced

39 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

TABLE 19-Re8uit8 of 8ucr08e analY8es made on individual carloads of C P 807 first stubble cane at Reserve La Oct 29 1935

Car Weigbtof IYield of00Experiment plot No and cut No cane t~~~Je

Pouooa Poundl 114 12200 16887 141 11800 IM72 183 12040 16072 121 11320 1M 52 152 10360 1M 94

c30-C cut L 109 8400 14821 139 13880 16803 105 11920 16845 82 11580 10025 13 7620 15383 81 2180 161IG

erage 15715

10980 162M 13laquo0 1M 09 13120 162011 13120 15215

-B m Lbull ( ~ 11180 14727 13460 IMM 12940 15217 12980 15111 5240 14934

verage 1M 04

2Z1 13 460 1M 22

c30-B cut 2 ~ Itll lijj1

Average ==1-------1---1-68-g-S

SUMMARY OF EXPERH1ENTS CONDUCTED IN COOPERATION WITH THE LOUISiANA AGRICULTURAL EXPERUIENl STATION

During 1934 only two cooperative experiments were carried on with the Louisiana Agricultural Experiment Station but in 1935 the numshyber was increased to seven The fields for all the cooperative experishyments were selected jointly with a representative of the experiment station and with the assistance of A M ONeal associate soil techshynologist of the Bureau of Plant Industry and officials of the sugar companies on whose properties the experiments were conducted These fields were selected with the greatest possible care to get the areas most comparable as to soil type fertility stand size of cane and past treatment The parasites were furnished by both cooperashytors and released at a time agreeable to both The egg examinations and infestation counts were made both jointly and independently by both cooperatGTS A representative of one or both was present at the time the experiments were harvested to obtan yield data

In 1934 parasites were released in the 2 cooperative experiments during June at the rate of 11950 per acre in c1 and 9241 per ccre in c2 During June July and August a total of 17930 parasites were released per acre in c1 and 18700 parasites were released per acre in c2

Collections of borer eggs were made in both cooperative experiments during April June July August and September The first parshyasitized eggs found in the cooperative experiments were collected

40 TEOHNICAL BULLETIN 743 U S DEPT m~ AGRICULTURE

from the check in c1 on June 26 The final percentage of parasitizashytion averaged only slightly higher in the colonized plots than in the checks

Infestation counts were made on at least 200 stalks in each of the colonized buffer and check pl(lts of both experiments The pershycentage of bored joints WfiS somewhat higher in the colonized than in the check plots The infestation counts are given in table 12 As shown in table 15 Trichogramma releases neither increased the pershycentage of milloble stfilks nor decreased the borer infestation in unmilshylable plants in the six cooperative experiments in which these data were obtained

The cane in all three plots of c1 was windrowed and harvested at approximately the sume time In the colonized plot of c1 the yield of sugar per acre WfiS 55 pounds higher than for the check but in the buffer it was more than 100 pounds higher than in the colonized or check plotf In c2 the yield of sugar in the colonized plot wus less thun for the buffer or check plots of the same experiment (table 16)

Parasites were released in 3 of the cooperative experiments during June 1935 at lL rute higher thfin 5000 per acre The number of parasites relefised in all seven during June July and August ayeraged between 15000 und 43000 per acre The information on the pfirasite releases is given in table 7

ThG percentage of parasitizfition in the colonized plots of c13 e19 and c20 did not average so high during July as in the buflers and checks Late in August and during September the parositization in the colonized buffer and check plots was about the same In the four other cooperatiy( experiments parasitized eggs were found during the latter part of July in the plot intended to be used as the check of c30 where the averngc parnsitization WfiS 217 percent nnd in the plot to be colonized find the buffer plot in c31 where it was 261 and 581 percent respectively before any releases were made No parasitization wns found during July in c32 or c33 During the latter part of August find in September the pamsitization in these four experiments averuged about the same

The percentage of bored joints in c13 c19 and c20 where parasites were released in June averaged about the same for the colonized buffer and check plots In the four experiments where the releases were made during August the percentage of bored joints was about the same in two experiments and slightly in favor of the colonized in one experiment and in the check in the other The data on the infestation counts are given in table 12

The yield of sugar per acre in the three experiments where the parashysites were released in June was slightly higher in the checks than in the colonized plots In the four that received the parasites in August the yield of sugar was about the same in two slightly in favor of the colonized in one and considerably in favor of the check plot in the other The yipld data al( given in table 16

The results of the cooperative experiments do not show any conshysistent gain in favor of the colonized plots The percentage of parasitization number of bored joints and yield of sugar per acre averaged about the same for the nine experiments that were conducted during 1934 and 1935

41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

i

i

J

l I t

0

t

r r

~

tshy -1 i

11 j

I I

L

39 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

TABLE 19-Re8uit8 of 8ucr08e analY8es made on individual carloads of C P 807 first stubble cane at Reserve La Oct 29 1935

Car Weigbtof IYield of00Experiment plot No and cut No cane t~~~Je

Pouooa Poundl 114 12200 16887 141 11800 IM72 183 12040 16072 121 11320 1M 52 152 10360 1M 94

c30-C cut L 109 8400 14821 139 13880 16803 105 11920 16845 82 11580 10025 13 7620 15383 81 2180 161IG

erage 15715

10980 162M 13laquo0 1M 09 13120 162011 13120 15215

-B m Lbull ( ~ 11180 14727 13460 IMM 12940 15217 12980 15111 5240 14934

verage 1M 04

2Z1 13 460 1M 22

c30-B cut 2 ~ Itll lijj1

Average ==1-------1---1-68-g-S

SUMMARY OF EXPERH1ENTS CONDUCTED IN COOPERATION WITH THE LOUISiANA AGRICULTURAL EXPERUIENl STATION

During 1934 only two cooperative experiments were carried on with the Louisiana Agricultural Experiment Station but in 1935 the numshyber was increased to seven The fields for all the cooperative experishyments were selected jointly with a representative of the experiment station and with the assistance of A M ONeal associate soil techshynologist of the Bureau of Plant Industry and officials of the sugar companies on whose properties the experiments were conducted These fields were selected with the greatest possible care to get the areas most comparable as to soil type fertility stand size of cane and past treatment The parasites were furnished by both cooperashytors and released at a time agreeable to both The egg examinations and infestation counts were made both jointly and independently by both cooperatGTS A representative of one or both was present at the time the experiments were harvested to obtan yield data

In 1934 parasites were released in the 2 cooperative experiments during June at the rate of 11950 per acre in c1 and 9241 per ccre in c2 During June July and August a total of 17930 parasites were released per acre in c1 and 18700 parasites were released per acre in c2

Collections of borer eggs were made in both cooperative experiments during April June July August and September The first parshyasitized eggs found in the cooperative experiments were collected

40 TEOHNICAL BULLETIN 743 U S DEPT m~ AGRICULTURE

from the check in c1 on June 26 The final percentage of parasitizashytion averaged only slightly higher in the colonized plots than in the checks

Infestation counts were made on at least 200 stalks in each of the colonized buffer and check pl(lts of both experiments The pershycentage of bored joints WfiS somewhat higher in the colonized than in the check plots The infestation counts are given in table 12 As shown in table 15 Trichogramma releases neither increased the pershycentage of milloble stfilks nor decreased the borer infestation in unmilshylable plants in the six cooperative experiments in which these data were obtained

The cane in all three plots of c1 was windrowed and harvested at approximately the sume time In the colonized plot of c1 the yield of sugar per acre WfiS 55 pounds higher than for the check but in the buffer it was more than 100 pounds higher than in the colonized or check plotf In c2 the yield of sugar in the colonized plot wus less thun for the buffer or check plots of the same experiment (table 16)

Parasites were released in 3 of the cooperative experiments during June 1935 at lL rute higher thfin 5000 per acre The number of parasites relefised in all seven during June July and August ayeraged between 15000 und 43000 per acre The information on the pfirasite releases is given in table 7

ThG percentage of parasitizfition in the colonized plots of c13 e19 and c20 did not average so high during July as in the buflers and checks Late in August and during September the parositization in the colonized buffer and check plots was about the same In the four other cooperatiy( experiments parasitized eggs were found during the latter part of July in the plot intended to be used as the check of c30 where the averngc parnsitization WfiS 217 percent nnd in the plot to be colonized find the buffer plot in c31 where it was 261 and 581 percent respectively before any releases were made No parasitization wns found during July in c32 or c33 During the latter part of August find in September the pamsitization in these four experiments averuged about the same

The percentage of bored joints in c13 c19 and c20 where parasites were released in June averaged about the same for the colonized buffer and check plots In the four experiments where the releases were made during August the percentage of bored joints was about the same in two experiments and slightly in favor of the colonized in one experiment and in the check in the other The data on the infestation counts are given in table 12

The yield of sugar per acre in the three experiments where the parashysites were released in June was slightly higher in the checks than in the colonized plots In the four that received the parasites in August the yield of sugar was about the same in two slightly in favor of the colonized in one and considerably in favor of the check plot in the other The yipld data al( given in table 16

The results of the cooperative experiments do not show any conshysistent gain in favor of the colonized plots The percentage of parasitization number of bored joints and yield of sugar per acre averaged about the same for the nine experiments that were conducted during 1934 and 1935

41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

i

i

J

l I t

0

t

r r

~

tshy -1 i

11 j

I I

L

40 TEOHNICAL BULLETIN 743 U S DEPT m~ AGRICULTURE

from the check in c1 on June 26 The final percentage of parasitizashytion averaged only slightly higher in the colonized plots than in the checks

Infestation counts were made on at least 200 stalks in each of the colonized buffer and check pl(lts of both experiments The pershycentage of bored joints WfiS somewhat higher in the colonized than in the check plots The infestation counts are given in table 12 As shown in table 15 Trichogramma releases neither increased the pershycentage of milloble stfilks nor decreased the borer infestation in unmilshylable plants in the six cooperative experiments in which these data were obtained

The cane in all three plots of c1 was windrowed and harvested at approximately the sume time In the colonized plot of c1 the yield of sugar per acre WfiS 55 pounds higher than for the check but in the buffer it was more than 100 pounds higher than in the colonized or check plotf In c2 the yield of sugar in the colonized plot wus less thun for the buffer or check plots of the same experiment (table 16)

Parasites were released in 3 of the cooperative experiments during June 1935 at lL rute higher thfin 5000 per acre The number of parasites relefised in all seven during June July and August ayeraged between 15000 und 43000 per acre The information on the pfirasite releases is given in table 7

ThG percentage of parasitizfition in the colonized plots of c13 e19 and c20 did not average so high during July as in the buflers and checks Late in August and during September the parositization in the colonized buffer and check plots was about the same In the four other cooperatiy( experiments parasitized eggs were found during the latter part of July in the plot intended to be used as the check of c30 where the averngc parnsitization WfiS 217 percent nnd in the plot to be colonized find the buffer plot in c31 where it was 261 and 581 percent respectively before any releases were made No parasitization wns found during July in c32 or c33 During the latter part of August find in September the pamsitization in these four experiments averuged about the same

The percentage of bored joints in c13 c19 and c20 where parasites were released in June averaged about the same for the colonized buffer and check plots In the four experiments where the releases were made during August the percentage of bored joints was about the same in two experiments and slightly in favor of the colonized in one experiment and in the check in the other The data on the infestation counts are given in table 12

The yield of sugar per acre in the three experiments where the parashysites were released in June was slightly higher in the checks than in the colonized plots In the four that received the parasites in August the yield of sugar was about the same in two slightly in favor of the colonized in one and considerably in favor of the check plot in the other The yipld data al( given in table 16

The results of the cooperative experiments do not show any conshysistent gain in favor of the colonized plots The percentage of parasitization number of bored joints and yield of sugar per acre averaged about the same for the nine experiments that were conducted during 1934 and 1935

41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

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41 EXPERIMENTS FOR CONTROL OF SUGARCANE BORER

SUMMARY AND CONCLUSIONS

Experiments were conducted for three seasons to ascertain whether or not the sugarcane borer (Diatraea saccharalis (F)) eould be conshytrolled in Louisiana by mass liberations of Trichogramma minutum Riley

Several lots of bagworm eggs were placed in the field during the winter and early part of spring but no parasitization by Trichoshygramma was obtained A Trichogramma adult however was colshylected in the winter and several species of moths were found depositing eggs at this time which could serve as hosts

Experiments conducted in April 1934 showed that Trichogramma dispersed as far as 100 feet within 48 hours after release

It was apparent from a comparison of the numbers of joints bored externally and internally that the count of joints bored externally can be used as a reliable indication of the actual internal borer injury

A definite correlation is shown between the percentage of parasitshyization and host density A study of egg collections and of the correshylation bllL-cen parasitization and host density indicates that very little reliability can be placed on the increase of parasitization prior to August as an indicator of sugarcane borer control

Every precaution was taken to see that the plots selected for the experiments on the control of the borer by the mass liberation of Trichogramma were uniform in every respect Each experiment conshysisted of a colonized and a check area which were separated by a buffer area in 1934 and 1935 and in most cases in 1933 Parasites were released at the rate of from 10000 to 45000 per acre during the 3 seasons

In comparing the progress of parasitization of the borer egg clusters found throughout the three seasons very little difference was observed between the percentages of parasitization in the colonized buffer and check plots

A study of the infestations in the stalk and joint showed that the borer infestation in the plots in which Trichogramma parasites were released increased to as great an extent as in the check plots

Factory analyses for sugar content and the net weight of an th cane harvested from each plot was used to obtain the amount of sugar and cane produced per acre in the various plots No relationship was evident between Trichogramma releases and increased yields yet such a relationship certainly should have appeared in the large number of experiments conducted had this practice resulted in any significant increase in yield

In some experiments the difference in yield between the two or three cuts composing the colonized plot was greater than that between the ayerage of the colonized and the average of the check cuts of the same experiment There was also considerable variation in the pounds of sugar per ton of cane resulting from tests mnde on various carload lots of cane from the same cut These differences indicate the great variation in yield that occurs in the average cut of sugarcane

Thus the results of the experiments conducted during the three seasons show that releases of Trichogramma minutum are of no value in thE control of the sugarcane borer in Louisiana The colonization of Tlichogramma as l field practice for the control of the sugarcane borer is therefore not recommended

42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

i

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0

t

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tshy -1 i

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42 TEIJHNICAL BULLETIN 743 U S DEPT OF AGRICULTURE

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

LITERATURE CITED ALLEN H W and WARREN A J

1932 THE RESULTS FROM TWO YEARS EXPERIMENTS IN MASS LIBERATIONS OF TRICHOGRAMMA MINUTUM AGAINST THE ORIENTAL FRUIT MOTH Jour Econ Ent 25 374-380 mus

CLAUSEN CURTIS P 1935 INSECT PARASITES AND PREDATORS OF INSECT PESTS U S Dept

Agr Cir 346 22 pp mus CLEARE L D JR

1929 MOTH BORER CONTROL IN BRITISH GUIANA 4th Internatl Congo Ent Trans pp [131]-137

1934 SUGAR-CANE MOTH-BORER INVESTIGATIONS IN BRITISH GUUNA THE PRESENT POSITION Agr Jour Brit Guiana 5 (1) [13]-21

FLANDERS S E 1929 THE MASS PRODUCTION OF TRICHOGRAMMA MINUTUM RILEY AND

OBSERVATIONS ON THE NATURAL AND ARTIFICIAL PARASITISM OF THE CODLING MOTH EGG 4th Internatl Congo Ent Trans pp [110]-130 mus

HINDS W E OSTERBERGER B A and DUGAS A L 1933 REVIEW OF SIX SEASONS WORK IN LOUISIANA IN CONTROLLING THE

SUGAR CANE MOTH BORER BY FIELD COLONIZAlIONS OF ITS EGG PARASITE TRICHOGRAlIIlII MINUTUM RILEY La Agr Expt Sta Bul 235 36 pp illus

--- OSTERBERGER B A and DUGAS A L 1934 SUGAR CANE MOTH BORER CONTROL BY TRICHOGRAMMA IIUNUTUM

RILEY REPORT ON EXPERIMENTAL WORK FOR 1933 La Agr Expt Sta Bul 248 34 pp illus

--- and SPENCER HERBERT 1928 UTILIZATION OF TRICHOGRAMMA JlllNUTUM FOR CONTROL OF THE

SUGARCANE BORER Jour Econ Ent 21 273-279 illus --- and SPENCER HERBERT

1930 PROGRESS IN THE UTILIZATION 01 TRICHOGRA~llIA ~IlNUT1r~l IN CANE BORER CONTROL IN LOUISIANA DURING 1929 Jour Econ Ent 23 121-127

JAYNES II A and BYNUM E K 1936 A PRELIMINARY REPORT ON THE USE OF THE EGG PARASITE TRICHOshy

GRAMMA JlIINUTUlII RILEY FOR THE CONTROL OF THE SUGARCANE BORER Sugar Bul 14 (19) 1-4

LIST GEO M and DAVIS L G 1932 TilE USE OF TRICHOGRAMMA MINUTUM (HYMENOPTERA CHALCIDIDAE)

RILEY IN THE CONTROL OF THE CODLING MOTH IN COLORADO Jour Econ Ent 25 981-985

PETERSON ALVAH 1930 A BIOLOGICAL STUDY OF TRICHOGRAMMA MINUTUM RILEY AS AN EGG

PARASITE OF THE ORIENTAL FRUIT MOTH U S Dept Agr Tech Bul 215 22 pp illus

SCHREAD J C 1935 COOPERATIVE EUlI_EAN CORN BORER EGG PARASITISM INVESTIshy

GATION Conn Agr Expt Sta Bul 383 344-346 mus --- and GARMAN PHILIP

1933 STUDIES ON PASASITES OF THE ORIENTAL FRUIT MOTH 1 TRICHOshyGRAMMA Conn Agr Expt Sta Bul 353 691-756 illus

SMYTH E GRAYWOOD 1933 TECHNIQUE IN THE MASS PRODUCTION OF TRICHOGRAMMA Jour

Econ Ent 26 768-774 illus TUCKER R W E

1935 A REVIEW OF CONTROL WORK ON DIATR~EA SACCHARALIS F IN BARBADOS Internatl Soc Sugar Cane Technol Congo Proc 5 386-397

ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

shy

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ORGANIZATION OF THE UNITED STAnS DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary oj Agriculture ___________________ CLAUDE R WICKARD

Under Secretary _________________________ PAUL H ApPLEBY

Assistant Secretary ________________ _____ GROVER B HILL

Director oj InJormalion ___________________ MORSE SALISBURY

Director oj Extension Work ________________ M L WILSON Director oj Finance_______________________ W A JUMP

Director oj PersonneL ______ __________ __ Roy F HENDRICKSON

Director oj Research ______________________ JAMES T JARDINE

Director oj Marketing_____________________ MILO R PERKINS Solicitor ____________________________ ____ MASTIN G WHITE

Land Use Coordinator ____________________ M S EISENHOWER

Office of Plant and Operations ______________ ARTHUR B THATCHER Chief Office oj C C C Activities ________________ FRED W MORRELL ChieJ Office oj Experiment Stations _______________ JAMES T JARDINE Chief Office oj Foreign Agricultural Relations ______ LESLIE A WHEELER Director Agricultural Adjustment Administration _____ R M EVANS Administrator Bureau oj Agricultural Chemistry and HENRY G KNIGHT ChieJ

Engineering Bureau oj Agricultural Economics __________ H R TOLLEY ChieJ Agricultural Marketing Service _____________ C W KITCHEN ChieJ Bureau oj Animal Industry________________ JOHN R MOHLER ChieJ Commodity Credit Corporation _____________ CARL B ROBBINS President Commodity Ecchange Administration________ JOSEPH M MEHL ChieJ Bureau oj Dairy Industry _________________ O E REED Chief Bureau oj Entomology and Plant Quarantine_ LEE A STRONG Chief Farm Credit Administration _______________ A G BLACK Governor Farm Security Administration _____________ C B BAIDWIN Administrator Federal Crop Insurance Corporation ________ LEROY K SMITH Manager Forest Service ____________________ _______ EARLE H CLAPP Acting ChieJ Bureau oj Home Economics ________________ LOUISE STANLEY CMeJ Library _________________________________ RALPH R SH-W Librarian Bureau oj Plant InduBtry _________________ E C AUCHTER ChieJ Rural Electrification Administration ________ HARRY SLATTERY Administrator Soil Conservation Service __________________ H H BENNETT Chief Surplus Marketing Administration ________ MILO R PERKINS Administrator

This bulletin is a contribution from

Bureau of Entomology and Plant Quarantine __ LEE A STRONG ChieJ Division 01 Cereal and Forage Insect C M PACK-RD Principal Enla-

Inrestigations mologist in Charge

43

a 1IOYIRIIJf1 II8TIR8 OFFICI 1141

For sale by the Superlntendent of Documents Washington D O - - bull - bull bull bull bull bull Price 10 cent~

- - I ~

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