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PROTECTION OF ELM TREES AGAINST THE DUTCH ELM

DISEASE (CERATOCYSTIS ULMI BUISM/MOREAU) IN THE

URBAH ENVIRONMENTS:

Some Factors Affecting Uptake and Translocation

of the Systemic Fungicide, Benomyl, by Roots

by

Raj Prasad

Chemical Control Research Institute

Canadian Forestry Service

Department of the Environment

Ottawa, Canada

CC-X-133

A Volunteer Paper Presented at the Second FAO/tUFRO

Wbrld Technical Consultation on Forest Diseases

New Delhi, India

April 7-12, 1975 F£|j } q jjgg

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SUMMARY

Controlled laboratory experiments employing elm seedlinqs grown in Hoagland solution, were carried out to test the effects

fof pH and three climatic factors {light intensity, temperature and relative humidity) on absorption, translocation and accumulation of benomyl (MBC-c") by roots. Autoradiographic and scintillation counting data demonstrated that all four factors influenced the

Irate of uptake and distribution. Maximum absorption and transport occurred under conditions of low pH, high light intensity (3000 f.c), high temperature (88°F) and low relative humidity (25%)

r Even though much of the activity was retained by the roots durlnq a 3 day absorption period, the translocation pattern was apoplastic and hence factors that regulated transpiration probably controlled

fthe pattern of movement of benomyl as well. It is suggested that stomatal behaviour (opening and closing and size of the stomatal aperture) together with cuticles and lenticels regulate the transpiration and translocation patterns of root/soil applied rungicides. ce

RESUME ■

On a realise des experiences en laboratoire sur des jeunes

pousses d'orrae croissant dans une solution de Hoagland, afin de determiner les effets de pH et trois facteurs climatiques

(1'intensity lumineuse, la temperature et l'humidite relative) sur I1absorption, le transport et 1'accumulation du benomyle (MBC marque" au CJ-4) par les racines. Les donnees provenant de I1autoradiographie et de la scintigraphie ont r^veig que les quatre facteurs infIuen9aient la vitesse d'absorption et de distribution. Les niveaux maximums d1absorption et de transport ont gte enregistrSs a base pH S forte intensite lumineuse (3000 f.c), a temperature eieve"e (88OF) et a faible taux d'humidite

relative (25%). Meme si, sur une periode d'absorption de trois jours, une grosse part de l'activite s'est concentrSe au niveau des racines, le transport itait apoplastique et, par consequent, les facteurs dont dependait la transpiration avaient probablement une influence directe sur le cheminement du benomyle. Nous croyons

done que lpaction des stomates {l'ouverture, la fermeture et la grandeur des ostioles), ainsi que celle des lenticelles et de la cuticule, gouvernent les mecanismes de la transpiration et du transport des fongicides absorbes au niveau des racines.

1

1

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r RESUMEN

de

fverificar los efectos de tres^cfrnrpe1^0"*.?0391*"'3' para de la luz, temperatura y humedad relativ^3 ?°S fintensidad desplazamiento y acumulacinr, ^o k -n , en ^ abs°rcion,

Los dates autoradiS^f "y" e^ecuen^o TC"C ■> ?" ldS "**■ F demonstraron que los tres factores in??™ escintalaciones

absorcion y distribusio'n. La abscrc?o'n I J°^e"ula.t.asa de se experimentaron baio condirinn0= *~ a!stribucion maximas (3000 f.c), elevada te^peratu??^?^9 u ^ensidad lumfnica (25%). Aungue las raS c n " n ' Y humedad "lativa baja

de la transpiracL'rPrSbableLiLqcon^olainne?^K'r''e91fladOreS dencias de distribucio'n del benomilo ?I ■tambien las ten-de^transpiracio'n y desplazamlen?o de" f unaicilaf? T* ̂ Patrones raices y la tierra regulan, junto co " y ciaa.s aplicados en las

esf ntiisV i r~n\ ' Clerre y tamano del nn'finin r

eatomatico) P ra' Clerre V tamano del orificio

-X-

IHTRODUOTICM

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METHODS

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r S-eeiiioUSe'J^rSSSntt'cSi3onsdofTe ̂ "^^ hi*°Fonically in

as a nutrient

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RESULTS AND DISCUSSICK ■ ■■

(i) Effects of Light - i,

The data obtained from the light and dark experiments are presented in Table I and indicate that light has a positive effect m uptake and transport of benomyl. Thus low light or cloudy days are likelv to impede the rate of absorption from the roots and this in turn may affect systemic action at the site of pathogenesis.

TABLE I

Effects of light and dark on root absorpticn and translccation of MBC-C14 by elm seedlings

Contents - iig MBC/g fresh weight

Itoot

Stem

Leaf

Total 158.91 100.00 74.46 100.00

(ii) Effects of Temperature

Under natural conditions there is a wide fluctuation in tenperature during the growing periods of elms. Temperature affects both the growth and the effectless of the chemical treatment. Table II shews the distribution into various parts of the plant at these tenperatures and Figs. 1 & 2 show the translccatxon pattern

into root, shoot and leaves.

TABLE II

Effects of tenperature on distribution of activity in elm ' seedlings following absorpticn of M3C-C14 by roots

Contents - wg/g fresh weight

Plant nart 6B°F Percent 88°F Percent Plant part ^ ̂ ^ of ^^

63.75 90.42 174.36 86.53 5.61 7.96 23.0 11.56

Leaf 1.14 1-62 3.85 1-91

Total 70.-50 100.00 201.51 100.00

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ti:Li) Effects of Relative Humidit

r te en &e leaves (Pr*sJ S S 1%7).

Ill

of n rcotj^sorpti,» and txanslocaUcn elm seedlings

Contents - pg/g fresh \jeight

Plant part u» Humidity Percent High Humidity Percent o£Total of total

Total i98.10 100.00

all three envir< mental factors and relative humidity) influence the rate of \S

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TflELE IV

Relationship between the degree of opening of elm stomata and varying levels of environmental factors

"

Environrrental

conditions

Percentage of stccnata observed at various

degrees of opening

fully open partially open fully closed

High Light - 3000 fc

(76°F, 60% R.H.)

No Light - 0 fc

(76°F, 60% R.H.)

High Tenp. - 88°F (3000 fc, 60% R.H.)

Low Teirp. - 68°F (3000 fc, 60% R.H.)

High R.H. - 95%

(3000 fc 76°F)

Low R.H. - 25%

(3000 fc - 7SOF)

B4

65

5

75

4

15

10

7

24

12

95

20

85

18

72

Thus, these findings demonstrate that climaUc and edaphic factors (light, tenperature, relative humidity and pH)'are of significance during bencryl application to elm roots (Figs. 3 & 4). Accordingly wanrer days with sunny periods are like:.y to favour SSri^tanic action because the rate of absorpt.on and translocation of bencnyl would be accelerated at that tine. This aeera to be largely accomplished by the stonatal irovanents and 1 .ranspiration rates of the leaves. Likewise, sunrrer application of bencmyl to soil and roots are likely to be nore effective than autmm a]plications. SSSuSms in weather cenditions might also account for differential effectiveness of benoryl treatments fron one geographical area to

another. Simlarly variations in soil conditions (pH) and benonYl formulation (acidic-alkaline) are litely to affeet the uptake ^ roots. Generally, acidic formulations and sonewhat acidic soils would pronote greater penetration and translocation of benorryl than alkaline formulations or basic soils (Prasad 1972).

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LITERATURE CITED

1. Biehn, W.L. andA.E. Di^nd (1971) . Plant Dis.

5" {1973'■

55-179-82

. 78, 309-18 P.K

8. Prasad, R. (1972). Canada Dept. of Envi™, Inf. Rept. CC-X-32. 33 pp.

9" (1972). Canada Dept. of Environ. Inf. Rept. CC-X-35. 23 pp.

(1974). Canada Dept. of Environ. Inf. Rept. CC-X-73. 14 pp.

. Weed Science 49(7): 149-156,

10.

11. Prasad, R., c.L. Foy and A.S. Crafts

12. Smalley, E.G. (1974). Phytopath. 61: 1351-54.

13. Stipes, R.J. (1969). Phytopatfi. 59: 1560.

14. Van Alfen, N.K. and G.S. Walton (174). Phytopath. 64: 1231-34.

t

■

-mm ^ ■■'-$?<&>

■:

V.

w

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o

H

M

1 Distribution pattern

of 1-

IBC-

C14

In el

m se

cdli

r.7,

5 fo

llow

ing

root

uptake at

lo

w te

mper

atur

(63°F) for 3

days.

Photograph of seedling-is on"*eft and autoradiograph on right,

l.ote

s.

-ov^t.ch!: into veins, rcargin a:

;d laminae of leaves.

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T3

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H

Tig. 2.

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APPENDIX III

0

LIGHT

TEMPERATURE

HUMIDITY

Comparative effects of

light, temperature and relative

humidity on absorption and translation of HBC-C1* by e

roots after a 3

day uptake.

KflJdW effects are brought

ii

then b

y lih

APPENDIX IV

'

8000

6000

E a

4000

8

2000

Figure

4.

EffecCa of pH on

and

of

14

of

period -

3 d»y«.