alabama a&m and auburn universities tomato insect

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ANR-1191 ALABAMA A&M AND AUBURN UNIVERSITIES www.aces.edu Tomato Insect Management Guide for Alabama M anagement of insect pests in tomatoes is a constantly changing process because of the introduction of new control tech- nologies and new pests that may threaten production. The key to successful pest management is to develop a regular scouting pro- gram to obtain information on pest and beneficial insect popu- lations that may be used to deter- mine if insecticide applications are needed. In general, new gen- eration insecticides act against a narrow range of pest species and are more costly than older, broad-spectrum materials. Thus, it is critical to properly identify the pests to be controlled and to determine if their presence or potential for damage warrants insecticide treatment. The only way to obtain this information is through routine scouting of fields. The purpose of this guide is to serve as a reference for insect pest identification and for general management guidelines. Please refer to the latest version of Extension publication ANR- 500, Alabama Pesticide Handbook, for current, complete insecticide recommendations and insecticide use restrictions and guidelines. General Recommendations for Scouting Tomato Fields Fields should be monitored for pests at least once, preferably twice, per week. Each tomato field or planting should be sam- pled separately, because condi- tions may be different in each field. Bring a 10X hand lens to help identify small insects and insect eggs and a data sheet to record the date and pest density. Keeping records will help iden- tify periods of peak pest activity during the season and can be used to predict when peak activity will occur in future years. Sample the field in a pat- tern that covers the entire field (i.e., follow an X, V, or zigzag pattern). It is best to check plants along the field edges sep- arately. Then walk at least 10 rows or 25 paces into the field to begin the X, V, or zigzag pattern. While walking the pattern, select 10 random sites, and sample 5 adjacent plants per site for 50 plants sampled per field. If an X or V pattern is used, select five sites along each “arm” of the pattern. Scouting for insect pests, damage, and disease problems can be done at the same time. The 50-plant sample can be done in less than an hour. Key Caterpillar Pests of Tomato Tomato Fruitworm and Beet Armyworm Depending on the year, envi- ronmental conditions, and prox- imity of adjacent host crops, infestations of these insects on tomatoes may range from very light to extremely severe. The tomato fruitworm (Helicoverpa zea), also known as the corn earworm and bollworm, and the beet armyworm (Spodoptera exigua) both overwinter in Alabama; so early season infesta- tions of these species may occur. Figure 1. Tomato fruitworm eggs Figure 2. Tomato fruitworm larvae boring into fruit Figure 3. Armyworm egg mass on tomato leaflet ARCHIVE

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ANR-1191

A L A B A M A A & M A N D A U B U R N U N I V E R S I T I E S

www.aces.edu

Tomato Insect Management Guide for Alabama

Management of insect pests

in tomatoes is a constantly

changing process because of the

introduction of new control tech-

nologies and new pests that may

threaten production. The key to

successful pest management is to

develop a regular scouting pro-

gram to obtain information on

pest and beneficial insect popu-

lations that may be used to deter-

mine if insecticide applications

are needed. In general, new gen-

eration insecticides act against a

narrow range of pest species

and are more costly than older,

broad-spectrum materials. Thus,

it is critical to properly identify

the pests to be controlled and to

determine if their presence or

potential for damage warrants

insecticide treatment. The only

way to obtain this information is

through routine scouting of

fields. The purpose of this guide

is to serve as a reference for

insect pest identification and for

general management guidelines.

Please refer to the latest version

of Extension publication ANR-

500, Alabama Pesticide

Handbook, for current, complete

insecticide recommendations

and insecticide use restrictions

and guidelines.

GeneralRecommendations forScouting Tomato Fields

Fields should be monitoredfor pests at least once, preferablytwice, per week. Each tomatofield or planting should be sam-pled separately, because condi-tions may be different in eachfield. Bring a 10X hand lens tohelp identify small insects andinsect eggs and a data sheet torecord the date and pest density.Keeping records will help iden-tify periods of peak pest activityduring the season and can beused to predict when peakactivity will occur in futureyears. Sample the field in a pat-tern that covers the entire field(i.e., follow an X, V, or zigzagpattern). It is best to checkplants along the field edges sep-arately. Then walk at least 10rows or 25 paces into the field tobegin the X, V, or zigzag pattern.While walking the pattern, select10 random sites, and sample 5adjacent plants per site for 50plants sampled per field. If an Xor V pattern is used, select fivesites along each “arm” of thepattern. Scouting for insect pests,damage, and disease problems

can be done at the same time.The 50-plant sample can bedone in less than an hour.

Key Caterpillar Pestsof Tomato

Tomato Fruitworm andBeet Armyworm

Depending on the year, envi-ronmental conditions, and prox-imity of adjacent host crops, infestations of these insects ontomatoes may range from verylight to extremely severe. Thetomato fruitworm (Helicoverpazea), also known as the cornearworm and bollworm, and thebeet armyworm (Spodoptera exigua) both overwinter inAlabama; so early season infesta-tions of these species may occur.

Figure 1. Tomato fruitworm eggs Figure 2. Tomato fruitworm larvaeboring into fruit

Figure 3. Armyworm egg mass ontomato leaflet

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2 Alabama Cooperative Extension System

However, later season tomatoplantings are often damagedmore severely because fruit-worm and armyworm popula-tions generally increase as theseason progresses. It is commonthat the most severe fruitwormdamage in tomatoes occurs afterdry-down or harvest of adjacentcorn, and that heavy beet army-worm damage in tomatoesoccurs after population buildupon cotton.

Because fruitworm andarmyworm are considered occa-sional pests in Alabama tomatofields, prophylactic or calendar-based insecticide sprays are notrecommended. A calendar-basedspray program is not cost-effective, will destroy naturalinsect enemies (i.e., parasitesand predators) of fruitworm andarmyworm, and will pose ahazard to public health and theenvironment. A more effectivestrategy for managing the fruit-worm and armyworm is to mon-itor fields regularly for signs ofinsects or damage and to applyan insecticide only when neces-sary. Field trials in Alabamatomatoes have demonstrated that use of the insect monitoringprogram will result in an averagesavings of $44 to $65 per acre ininsecticide costs alone whencompared with a program whereinsecticides are applied on aweekly basis. In addition to applying insecticides only whenneeded, the fruitworm/army-worm scouting program enablesgrowers to apply sprays at theoptimal time, when the wormsare young and most susceptibleto insecticides. The followingdiscussion will provide the specific information needed to implement the tomato fruit-worm and armyworm management program.

How to Identify TomatoFruitworm and Damage

The adult fruitworm moth istan or buff-colored, with darkspots on the outer edge of theforewings. Moths are 1 inchlong, with a wing span of 1.5inches. They are active at night,and the females are attracted totomato plants in the flower andfruiting stages for egg laying.Eggs are laid singly on foliagenear the flowers or developingfruit, usually on the outer por-tions of the plant (Figure 1).Fruitworm eggs are about thesize of a pinhead, hemisphericalin shape, and slightly flattened atthe top, with 12 or more distinctridges radiating from the top.They are white when laid butdevelop a reddish brown ringafter about 24 hours. The eggsturn black if parasitized by thetiny Trichogramma wasps, whichare usually prevalent in fieldsnot sprayed regularly with insec-ticides. Young larvae have sev-eral rows of black bumps alongtheir backs and two bristles orwhisker-like hairs that growfrom each bump. Older larvaevary in color from light green toreddish-brown and often havestripes running lengthwise downthe body. The older larvae alsohave distinct hairs covering largeportions of their skin. This char-acteristic can be used to distin-guish fruitworm larvae fromarmyworm larvae that have nobody hairs.

Newly hatched larvae usuallyenter tomato fruit at the stemend when the fruit is small andgreen (Figure 2). They boredeeply into the fruit and duringdevelopment they may emergefrom one fruit and enter another.Their feeding results in a watery,internal cavity filled with feces;damaged fruit will ripen prema-turely and be susceptible to secondary invasion by fungi and bacteria.

How to Identify BeetArmyworm and Damage

The beet armyworm moth isslightly smaller than the fruit-worm moth and darker, with amottled, grayish brown color.Like the fruitworm, armywormmoths are active at night, buteggs are deposited in massescovered by white, fluffy scalesfrom the female (Figure 3). Beetarmyworm egg masses aredeposited randomly throughoutthe tomato plant, often on theunderside of leaves. It iscommon to see many smallarmyworm larvae feeding on theunderside of tomato leavesbefore they disperse throughoutthe plant. Beet armyworm larvaeare smooth, without hairs, andvary in color from dull green toblack (Figure 4). Older larvaehave a broad, light-colored stripealong the side of the body. Beetarmyworm larvae usually have adark spot on the side of thebody in the front just above themiddle pair of true legs.

Beet armyworm is primarily a foliage feeder, but they willalso attack fruit, usually creatingsingle or closely grouped roundor irregularly shaped holes(Figure 5). Feeding damage isusually superficial, and larvaeonly occasionally develop insidethe fruit. Unfortunately, decay organisms enter the feeding-damaged areas and can rot thefruit.

Sampling for TomatoFruitworm and Armyworm

Because beet armyworm is a foliage feeder, infestations maybegin early—before the flowerand fruit stage. Therefore, it isprudent to check young plantsregularly for beet armyworm egg masses or small larvae. Thepresence of beet armyworm larvae can also be detected byshaking foliage over a shakecloth. The critical period for

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Tomato Insect Management Guide for Alabama 3

tomato fruitworm and fruitwormegg sampling begins at floweror, at the latest, when there are asignificant number of green fruitat least 1 inch in diameter.Fruitworms are usually not aconcern before flowering unlesshigh numbers are present.

Sample for fruitworm eggsand armyworm egg masses byselecting the first fully expandedleaf and all new foliage abovethis leaf on 5 consecutive plantsin each of the 10 random loca-tions per field. The first fully expanded leaf will be located atthe top of the plant where newgrowth begins. For samplingpurposes, a “leaf” is defined asall the foliage along a branchstem (branching from a mainstem). Therefore a leaf mayinclude as many as 8 to10leaflets along the stem; eachleaflet, upper and lower surface,should be checked for eggs.Although fruitworm eggs aresmall, they stand out and areeasily detected with a little prac-tice. Don’t count black, para-sitized fruitworm eggs in thesample. Beet armyworm eggmasses are covered by fuzzywhite scales and are easy tospot. It is a good idea to checkor shake some of the lower foliage for beet armyworm eggmasses and larvae after the firstfully expanded leaf is sampled.

Fruit sampling serves as anextra precaution and a backup to the foliage sampling for wormsand worm eggs. Pick 100 fruitsamples at least 1 inch in diameterat random throughout the field.Check to see if any fruit haveworm-feeding damage. Sliceopen damaged fruit to determineif damage is due to fruitworm(feeding deep inside fruit, fecesoften present) or armyworm(feeding usually confined to thesurface). It is important to knowwhich worm species is present to select the most effective insecticide needed.

When to Treat for TomatoFruitworm and Armyworm

For producers with a low or0 threshold for worm-damagedfruit, an insecticide application isrecommended if 1 fruitworm eggor 1 beet armyworm egg mass isfound on any of the 50 plantssampled per field. Growers thatcan tolerate a low percentage ofdamaged fruit may use a fruit-worm egg threshold of 3 to 5eggs per 50 plants. Damagethresholds have not been devel-oped for damaged fruit samplesin fresh-market tomatoes, butCalifornia processing tomatogrowers use a threshold of 3percent worm-damaged fruitfrom 100 fruit samples randomlychosen in the field.

Other ArmywormSpecies

Several other armywormspecies may occasionally infestAlabama tomato fields and causedamage. These include plainarmyworms (Pseudaletiaunipuncta), yellowstriped army-worms (Spodoptera ornithogalli),and southern armyworms(Spodoptera eridania). Plainarmyworms are variously markedin brown, black, grey, or green,with head sutures forming an inverted “Y”. Yellowstriped army-worms have dark heads and darklateral marks bisected by a thin,white line on each segment behind the true legs. Southernarmyworms are dark caterpillars,with two yellowish lateral linesinterrupted by a large dark spoton the first abdominal segment.The larger, mature larvae havetwo rows of dark triangles on theupper surface. Damage is similarto that done by the beet army-worm, which feeds primarily on foliage but will attack fruitwhen encountered. Samplingand control guidelines are thesame as those described for the beet armyworm.

Cabbage LooperCabbage loopers (Tricho-

plusia ni) are green caterpillarswith white stripes runninglengthwise down the body(Figure 6). Loopers have onlythree pairs of fleshy prolegs inthe rear. The young larvae areoften found on the underside ofleaves where they feed ontender leaf tissue, leaving mostveins intact. Because loopersfeed only on foliage, damage isusually not severe enough towarrant treatment. After fruit setsand scouting indicates severefoliage feeding such that fruitbecome prone to sunburn, insec-ticide application may bewarranted.

Tomato PinwormNewly hatched larvae of

tomato pinworm (Keiferia lycop-ersicella) are yellow-grey and lessthan 1 mm long. Mature larvaeare darker and covered with darkpurple spots (Figure 7). Earlystage larvae feed on leaves andcreate blotch-type mines (Figure8). This damage appears similarto leaf-miner damage. In somecases, larvae may tie the leaf together with silk and feed inthe protected area inside. Laterstage larvae that bore into thefruit, usually at the calyx or stemend, cause the most seriousdamage (Figure 9). Pinworm larvae make dry burrows in thecore and do not penetrate veryfar into the fruit. When infestedfruit is picked, caterpillars maybe difficult to detect, unless theyhave been feeding long enoughto create small piles of browngranular frass at the edge of thecalyx. Because the pinworm hasmany generations per season, itbecomes a more serious pest asthe season advances. The greatestdamage occurs where tomatoesare grown from early in the season to late in the fall or

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4 Alabama Cooperative Extension System

Figure 4. Beet armyworm larvae Figure 5. Beet armyworm feedingdamage on tomato fruit

Figure 6. A cabbage looper

Figure 7. A mature tomato pinwormlarvae

Figure 8. Tomato pinworm leafdamage

Figure 9. Tomato pinworm damageto fruit

Figure 12. Thrips in a tomato blossomFigure 11. Potato aphids on a tomato leaf

Figure 10. Tomato hornworm

Figure 13. Bronzing symptoms oftomato spotted wilt on tomato leaf

Figure 14. Symptoms of tomatospotted wilt on fruit

Figure 15. An adult sweetpotatowhitefly

Figure 18. An adult stinkbug

Figure 17. Irregular ripeningsymptom caused by sweetpotatoFigure 16. A whitefly nymph

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Tomato Insect Management Guide for Alabama 5

Figure 19. Stinkbug eggs

Figure 20. Stinkbug damage on fruitFigure 21. Typical symptom of leafminer damage

Figure 24. An adult Colorado potatobeetleFigure 23. Flea beetle adults and

signs of feeding damage

Figure 22. A blister beetle

Figure 25. Larvae of Coloradopotato beetle

where late plantings are adjacentto early planted-infested fields.Pinworm is more severe in southAlabama.

Pinworms can be controlledwith mating disruption tech-niques or insecticides. Matingdisruption pheromones havebeen used successfully in areaswhere pinworms have devel-oped resistance to insecticides.Mating disruption is most suc-cessful where fields are isolatedor whole areas are treated.Pheromone traps should be usedto detect the presence of adultmoths. As soon as moths beginto appear in pheromone traps,apply mating disruptionpheromone products. If nearbyinfested tomato fields are termi-nated or abandoned, adults canimmigrate into late-planted fieldsin large numbers. If monitoringdetects a significant movement,consider border treatments. Toreduce future populations ofpinworm, destroy crop residues

after harvest by burning orplowing-under. If pinworm is aserious pest in the area, avoidgrowing more than one crop peryear. Check transplants carefullyfor pinworm infestation beforesetting them in the field.

HornwormsHornworm (Manduca spp.)

larvae usually have green bodieswith seven diagonal whitestripes on the side, or eight V-shaped markings, depending onthe species (Figure 10). Thename comes from the large hornon the posterior end of thebody. Hornworms can growlonger than 41⁄2 inches in length.They strip the leaves and may

cause feeding scars on fruit.Hornworms are often controllednaturally by parasites. Parasitizedhornworms may be identified by the presence of many white cocoons attached to the upperbody surface. The preferred man-agement approach is to wait untilfruit begins to mature before applying insecticides. Insecticidesmay be applied sooner if extensivefoliar feeding is observed. Insecti-cides are not highly effectiveagainst late stage larvae.

For more informationregarding caterpillar pests, seeExtension publication ANR-1121,“Identifying Caterpillars in Field,Forage, and Horticultural Crops.”

Insect Vectors of VirusDisease: Aphids,Thrips, Whiteflies

AphidsAphids are small, soft-bodied

insects that vary in color frompale yellow to red to green toblack, depending on the species,the host plant, and time of season

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6 Alabama Cooperative Extension System

incidence of virus in tomatoes.Many tomato growers in Floridause reflective (aluminum-colored)mulch to delay the spread ofaphid or whitefly-transmittedvirus diseases. The reflectivemulch reflects UV light, whichthe insects perceive as light coming from the sky. This masksthe attractive color of the plants.

The most effective way to reduce aphid and aphid- vectored virus problems is toreduce the number of aphidsmigrating into the field. Oneway to do this is to implementregular weed control practices toeliminate weeds that may serveas alternate hosts for aphids in, or adjacent to, tomato fields.Predominant winter hosts for the green peach aphid are plantsin the Prunus genus, includingrose, peach, and plum. Pruningin peach orchards destroys manygreen peach aphid eggs. Orchardsor fruit tree areas adjacent totomato fields should be kept freeof weed hosts, and untendedpeach trees should be treatedwith insecticides or removed.Fruit trees adjacent to tomatoesmay be treated with insecticidesor dormant oils in the spring before tomatoes are planted.

Ultra-fine oils (Saf-T-Side,JMS Stylet Oil, etc) have shownsome effectiveness for manage-ment of aphids and virus. Oilsact in two ways. The highly refined oils dissolve or degradethe cuticle of soft-bodied insectslike aphids, causing direct mor-tality. It has also been shownthat oils sprayed on plants mayintercept the stylet-borne virusparticles from the aphid beforepenetration into the plant, therebydelaying infection. In general, oilsare not as effective as insecticidesfor aphid control because theyare not as toxic. Therefore, oilsprays may have to be appliedmore frequently. Also, for max-imum effectiveness, oils shouldbe sprayed in a volume of at

least 50, preferably 100, gallonsper acre (gpa) and using at least200 psi (preferably 400 psi) pres-sure. Oils are used frequently inCalifornia, where green peachaphids are highly insecticideresistant, for management ofaphid-vectored viruses incucurbit crops.

ThripsSeveral species of thrips may

infest tomatoes, including western(Frankliniella occindentalis) andeastern (Frankliniella tritici)flower thrips, melon thrips(Thrips palmi), and tobaccothrips (Frankliniella fusca).These are tiny (1⁄16 inch), slenderinsects that may vary in colorfrom yellow to dark brown orblack (Figure 12). They prefer to feed in flowers but also occurin flower and leaf buds and, occasionally, on leaves. Thripsdamage tomatoes in severalways. Feeding in blossoms maycause blossom drop, or fruit maynot develop properly andbecome deformed. Feeding on foliage may cause a bronzing orsilvering of foliage. Eggs insertedin fruit causes dimpling, and theinfested area may appear white.Thrips are also vectors of tomatospotted wilt virus (TSWV), a potentially devastating disease of tomato. Infected plants havedark lesions on the foliage(Figure 13) and fruit show charac-teristic halo markings (Figure 14).Refer to Extension publicationANR-836, “Virus Diseases ofTomato,” for more information on this disease.

Research has demonstratedthat even low numbers of thripsmay be enough to infest fieldswith TSWV. However, high pop-ulations are more likely to resultin a greater incidence of virus inthe field. To determine thripspresence, sample one flower perplant during the routine scoutingprocedure. Thrips may be visibleinside the flower using a hand

(Figure 11). Direct-feeding damage by aphids is rarely severeenough to kill plants. They pierceplant tissue with needlelikemouthparts, which may result inblossom shed or curling orstunting of new growth. Theyalso produce a sticky materialcalled honeydew that supportsgrowth of a black sooty moldfungus. However, aphid trans-mission and the spread of plantviruses cause greatest economicdamage. Aphid-vectored virusesand resultant virus disease epi-demics have severely limitedtomato production in northAlabama in recent years. Severaldifferent aphid species probablyare involved in the spread ofviruses to tomato fields, includingthe cotton aphid (Aphis gossypii),green peach aphid (Myzus per-sicae), and the potato aphid(Macrosiphum euphorbiae). Thegreen peach aphid and the potatoaphid are known to develop ontomato and are known to beefficient vectors of tomatoviruses. The cotton aphid is alsoan efficient virus vector but doesnot develop on tomato. Cottonaphid populations commonlybuild up on cotton, then moveto weeds and vegetable cropswhere they may acquire andtransmit virus.

While insecticides recom-mended for aphid control are effective at killing aphids, thereis no way to prevent the spreadof nonpersistent (stylet-borne)viruses in tomatoes with insecti-cides. This is because of theshort time needed to transmitthe virus by aphid feeding. Anaphid landing on an insecticide-treated plant will transmit thevirus before succumbing to theinsecticide. However, insecticidesapplied for aphids may delay thespread of the virus or reduce themagnitude of the disease.Application of imidacloprid(Admire) at planting has beenshown to reduce or delay the

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Tomato Insect Management Guide for Alabama 7

lens, or the flower may beshaken over a piece of paper todislodge the thrips for observa-tion. If the area has a history ofTSWV, insecticide application isrecommended if any thrips arefound. If TSWV has not been aproblem in the past, the recom-mended thrips treatmentthreshold is five thrips perflower. Application of imidaclo-prid (Admire) at planting mayhelp to delay the onset of TSWVsymptoms in the field. Recentresearch in Georgia has indi-cated that insecticides appliedduring the first 4 weeks aftertransplanting provide thegreatest protection against yieldreduction from TSWV. As indi-cated for aphid control, reflec-tive (aluminum-colored) mulchmay also help to reduce thripsinfestations and spread of TSWV.

WhitefliesThe adults are tiny, white or

yellowish winged insects thatrise in clouds above the plantwhen they are disturbed (Figure15). All growth stages are usuallylocated on the underside ofleaves. The immatures, ornymphs, are scalelike in appear-ance, immobile, and lack legs(Figure 16). Adults and nymphsproduce honeydew, which is a food source for sooty moldfungus. Large populations ofwhiteflies debilitate plants directlythrough sap removal and indirectlythrough shading effects of sootymold. The sweetpotato whitefly(Bemisia tabaci), sometimescalled the silverleaf whitefly(Bemisia argentifolii), may alsocause a physiological disordercalled irregular ripening, wherefruit fails to color evenly duringthe ripening process (Figure 17).This species of whitefly alsotransmits a plant virus, tomatomottle geminivirus (TMoV).TMoV has only been reported in Florida, but south Alabamagrowers should be on the lookoutfor this disease.

In Florida, successful man-agement has depended on theintegration of cultural, biological,and chemical control. Growersare encouraged to maintain atleast one crop-free period of 2months or more during whichfields are kept free of cropresidues to reduce the source ofvirus and whiteflies. If successiveplantings are required during theseason, they should be separatedthe maximum distance possibleby nonsusceptible crops.Application of imidacloprid(Admire) at planting has helpedto reduce whitefly populationsand the incidence of TMoV. Theuse of stylet oils (see aphid man-agement section) has alsodemonstrated some effectivenessfor management of whitefly andassociated virus diseases.

Other Insects AffectingTomato

StinkbugsThese insects in the “true

bug” group are distinctly shield-shaped and are either green orbrown (Figure 18). Immatures, ornymphs, look like adults but aresmall and lack wings. Eggs arekeg-shaped and are laid in clus-ters on foliage (Figure 19). Ongreen fruit, damage appears asdark pinpricks surrounded by alight discolored area (Figure 20).Stinkbugs (Nezara viridula) arehighly mobile but may be sam-pled by beating or shaking vinesand checking the soil under thebeat sheet for stinkbugs.

Treatment thresholds vary bylocation. In Florida, the thresholdis one bug per six plants onceplants set flowers. The publishedCalifornia threshold is 1⁄3 to 1⁄2stinkbug per beating sheet ortray. Application of imidacloprid(Admire) at planting is reportedto reduce stinkbug damage on tomato.

Leaf MinersLeaf miner (Liriomyza

sativae) adults are small flies,with a black head and yellowbetween the eyes, a blackthorax, and a tubelike ovipositorat the end of the abdomen. Eggsare inserted into leaf tissue, andthe yellow larva feeds betweenthe upper and lower leaf surface.This results in the characteristicserpentine mine containing astring of black fecal matter(Figure 21). Mature larvae dropto the ground (or plastic mulch),where they molt into dark brownpupae. Generally, leaf miners arenot a serious pest of tomatoes.Leaf mining reduces photosyn-thetic areas but usually notenough to reduce tomato yields.Occasionally, severe infestationsreduce foliage to the point wherefruit become sunburned.

Leaf miners suffer parasitismby a variety of parasitic waspsthat normally keep populationsin check. For this reason, applica-tion of highly toxic insecticides,like methomyl, that destroy natural enemies should be avoided. If control is necessary,use of narrow-range, or lesstoxic, insecticides is preferred.

Beetles (Blister Beetles,Flea Beetles, ColoradoPotato Beetle)

Beetles are foliage feedersand normally do not damage fruitunless populations are very high.Blister beetles are slender elon-gated beetles up to three-fourthsof an inch long with prominentheads (Figure 22). Their bodycolor varies but is usually black,or black with yellow margins orstripes. They produce stringy,black excrement, and their feeding results in ragged holeson the leaves. Flea beetles(Epitris spp.) are tiny dark bee-tles with enlarged hind legs thatenable them to jump awayinstantly when disturbed. They

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are more of a problem in thespring, when they move intotomatoes from adjacent weedyareas. They produce tiny roundholes in foliage (Figure 23).Colorado potato beetles (Leptino-tarsa decemlineata) feed onsolanaceous plants but preferpotato and eggplant to tomato.The adults have dark bodies withfive longitudinal yellow stripes oneach wing cover (Figure 24).Larvae are reddish with dark

spots. Both adults and larvaefeed on foliage (Figure 25).

Regular monitoring of plantswill easily detect the presence ofbeetles and their potential fordamage. Remember that low levels of defoliation will not haveany impact on yield, particularlywhen plants are mature. There-fore, insecticides are recom-mended only if feeding damageis moderate to severe. However,

beetle populations on plants(particularly Colorado potatobeetle) may build rapidly.Therefore, if beetles are detectedbut no insecticide is applied, it isrecommended that anothersample be taken within 2 days to determine if beetle numbers are increasing.

ANR-1191

Edward Sikora, Extension Plant Pathologist, Associate Professor, Entomology and PlantPathology, Auburn University. Originally prepared by Geoff Zehnder, former ExtensionEntomologist.

Use pesticides only according to the directions on the label. Follow all directions, precautions, and restrictions that arelisted. Do not use pesticides on plants that are not listed on the label.

The pesticide rates in this publication are recommended only if they are registered with the Environmental ProtectionAgency and the Alabama Department of Agriculture and Industries. If a registration is changed or cancelled, the rate listedhere is no longer recommended. Before you apply any pesticide, check with your county Extension agent for the latestinformation.

Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse orguarantee any product and does not recommend one product instead of another that might be similar.

For more information, call your county Extension office. Look in your telephone directory under your county’s name tofind the number.

Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, andother related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System(Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employmentto all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.

UPS, 15M30, New Nov 2000, ANR-1191

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