A study of DDT deposits on peach foliage and fruit treated for control of the oriental fruit moth

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Material Information

Title:
A study of DDT deposits on peach foliage and fruit treated for control of the oriental fruit moth
Physical Description:
6 p. : ; 27 cm.
Language:
English
Creator:
Brunson, M. H
Koblitsky, Louis
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington
Publication Date:

Subjects

Subjects / Keywords:
Oriental fruit moth -- Control -- New Jersey   ( lcsh )
Fruit -- Diseases and pests -- Control -- New Jersey   ( lcsh )
DDT (Insecticide) -- Testing   ( lcsh )
Genre:
bibliography   ( marcgt )
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 4).
General Note:
Caption title.
General Note:
"E-809."
General Note:
"November 1950."
Statement of Responsibility:
by M.H. Brunson and Louis Koblitsky.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030340483
oclc - 781129579
System ID:
AA00025256:00001

Full Text

November 1950


United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine



A STUDY OF DDT DEPOSITS ON PEACH FOLIAGE AND FRUIT
TREATED FOR CONTROL OF THE ORIENTAL FRUIT MOTH

By M. H. Brunson, Division of Fruit Insect Investigations,
and Louis Koblitsky, Division of Insecticide Investigations1/


In the use of DDT for the control of the oriental fruit moth (Grapholitha
molesta (Busck)), applications are generally made only during a period of
about 6 weeks prior to harvest. It seemed likely that the amounts of DDT
needed to protect the fruit during this period would give harvest residues
in excess of the administrative tolerance of 7 p. p.m. for apples and pears.
Therefore, in 1948 studies were made of the deposits on peach foliage and
fruit following different methods and schedules of application, including
their effectiveness in controlling the oriental fruit moth. The results of
these studies are especially opportune because of the recent hearings by
the Food and Drug Administration to establish a definite legal tolerance
for DDT residues on fruits. The toxicological investigations reported
by Lehman (2) suggest that 5 p. p. m. approaches the maximum amount
of DDT that could safely be allowed in any single food item.
The orchards in which the studies were made are located between
Marlton and Florence, N.J. The varieties Summercrest and Elberta
were used in the spray experiments and the variety Afterglow in the dust
experiments. The average ripening dates in this vicinity are August 21
for Summercrest, August 25 for Elberta, and August 29 for Afterglow.
The owners of the orchards applied the usual lead arsenate sprays for
control of the plum curculio (Conotrachelus nenuphar (Hbst.)) and sulfur
sprays or dusts for brown rot control.

Methods

Sprays were applied to plots of trees in six orchards. Each plot,
including the check, consisted of four trees, two corresponding trees in
each of two adjacent rows. Five plots in each orchard were treated


1/ E. L. Plasket assisted in the field work. W. P. Yetter and
temporary employees assisted in cutting fruit at harvest to determine
the degree of infestation.


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*, a ndJ th e h ots w e'..r e u s u a l l- s e.: ,1- ..t ed b y
.^0:,1- ases by) <.nlv one-. The s ra.- were
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ay c h s planned included a. liatons at 2-w;ek nI Mrv LAs
Sa l 'n 2 eefks b rftr h arrest in one sc1.. dul.,t d at
t- al With r it last :. '.lilati n 3 I v e-:k- before ry. i -v ~t .' -'.
*ay i;t were pie : I.determ i nTed in ace rdance wtth i.* ave rage


1r:p n 1! M.If r 1. z, va tie s rn jhi h obse rations wsre t! m7 z e. In
WHIM -::A aorable weather Ier.n.iiened the inr:or.% cIa to :K pr X.:: n tep .
3-,2 we k 1here were also sl.h ar.tioi.-, f:,-m An :.. :., iner .
w theI lastd a. 'jih atin. and harvest, be ause ri'.:.:.d ites varied
fr ii the av ra s. I s hedules that were ultimate' follow ., 1l.. :'..
s5nflr .,:.,: h ations for comparative pu.,j ises, ;,re r.-',,,wn in the -.d.
All sprays ontain. ,i 2 pounds of 50-D, r ent DDT wettable w!-r r
I *, Ti -:5
I1 two' oTre li: ,-. a 5-percent DI)T 'l-st .a,- a: plied. Lach lot c :.-
I>iist d of i0 11onsecutive trees in a row. Ten corres.i^.Jt r.: t:, S -.-; C:: .e .t
fr(L r treat, ,i trees by a b.f:'er row were ..-.,-d .,%, &he k:.. Th t.- d .-t
schedule plar.t d w : 3 ajppli< 2tio..-, 2 weeks apart, *he :ast .:.:p:.:,ati :. 2
weet'ks before ,"ivest. There were some variati .ro due t unfav..: weather and fruit r".,.:,, earlier :ha:. exp',- ted. The dates of ap'lic,-
tion are T>hown in 'h, talles. Dusts we, rt* [pli-d with a ro'ary har.
d.tel at the rate of approximately 1,2 t"r'.d ptr t:-..
In five or, hd,-'V- triplicate samples o f 50 leaves ea, h were btainea
for residue ;,.i lyses immeJ.ately :n'er eac h application n. ar.d at wN-ekvy
intervals there., vr until ', nex' .,pplicati.nl or harv .t1. Thr sam i'-l s
frni th s) ,yed lotss each c :,-ted of 10 leave f:m ": tht '.,.s : each
of 5 {)lo' I e l ise from the lusted plots of 5 leaves fr, :m. eaci .4f the 10
i *-' i "he plots. Each leaf was pla eId in a pint fruit ,r immedn:.'tely
ftr *ts envai from the tree to revenr the Io--. of i)DDT :'sit. I".t
.Jr/I wasi feli .ved from the leaves by extract.' .v h', h 125 ml. of a 21
11 xt: o If l)enzene aT d i- pro, .,' 1 for I ".,! .utes o1 t7..7 .. 1h e.
;: .: .i'"l | :J ii a 1( i- l. alitlua.[ was .ite rm .' d b'. t to*.,C hlorinr .
:::,'lI: Id ders n h rb d Ijy K oh ln sky, n C'h i -ho ln (I1). 1I;i, re .::>- fr- :-i '!,,
tI r'ip ate sa I(''les were a.,e ,,ed. I i', ave'.,,"e .,rea of .,' ., ach leav, .a
talk.ih ;a.1 ra! w1 ,as found to bV about 1 3,3 ...' c: (one surface *)).
}rM: 1,t san;{>les: for an :al sis were obltained fromn the s; ".,yed I"', *
iro n ::ied a tr lv [ tx f:,re ha rves::t l:,, tak ir ,' 5 fru its fr ": each o f ".h,, 5 lo '-'.
Ii 'tie di I t 'es a s:ample f 25 fruits was obtained at :.,: ,: "-. fr :-

s.. ::{.lr; aI-, :he v-ere ,nio frI the te es. ; a w, e t "e -htd .it the
la t 't v then tra sfer rred to 2- 12 ,'.,:Mon a :I I extract, .t on




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tumbling machine for 5 minutes with 500 ml. of the benzene-isopropanol
mixture. The extract was dried with anhydrous sodium sulfate and the
amount of DDT in a 400-ml. aliquant was determined by the total-chlorine
method.
The oriental fruit moth infestation in the fruit at harvesttime was
determined on samples of 200 fruits, 10 taken from each tree in the
sprayed plots and check and 200 at random from each dusted plot and
check. The fruits were cut and examined for larvae or signs of larval
feeding soon after the samples were obtained.

Results
Residues on leaves (table 1). --The residues on leaves from nine
initial spray applications averaged 11.1 micrograms per square centi-
meter. About 70 percent of the initial residue was lost during the week
after the first application; very little more was lost during the second and
third week. When DDT was applied in repeated sprays, the residues
increased a little with each application.
About four-fifths of the residues from the initial dust applications was
lost during the first week; there was a further loss during the second
week. Additional dust applications did not cause increases above the
initial deposit.

Residues on ripe fruit (table 2). --The amount of DDT on the sprayed
fruit at harvesttime apparently depended on the schedule. These residues
exceeded 7 p. p. m. in only two of nine treatments in which two or three
sprays were applied at intervals of 3 or 3-1/2 weeks. There was more
than 7 p. p. m. of DDT on the fruit in all plots in which three sprays were
applied at 2-week intervals. Harvest residues on the fruit dusted three
times at 2-week intervals were only 4 p. p.m. in both orchards. For the
most part there seemed to be no clear-cut relationship between the
interval between the last spray and harvesttime and the residue on the
fruit.

Relationship of DDT residue and schedule of application to ripe fruit
infestation. --In the sprayed orchards the best control of the oriental
fruit moth was obtained with the treatments that gave the highest harvest
residues, and the reduction in infestation was less than 80 percent where
the residue was less than 7 p. p. m. Furthermore, the control was usually
best in the plots in which the DDT residues on leaves had been heaviest
for approximately 6 weeks prior to harvest.
When three sprays were applied at 2-week intervals, fruit infestation
was reduced by an average of 80 percent. Three sprays applied at 3- or
3-1/2-week intervals were 14 percent more effective than two sprays
applied at the same intervals. The reduction in fruit infestation averaged
64 percent as a result of six treatments in which two sprays were applied
at approximately 3- or 3-1/2-week intervals, and 52 percent as a result
of three treatments in which one spray was applied 18 days before harvest.








u i!< aEm; a 'rb of >'.I i.'' u t 2 we~ks i; art, were re I iviely in-

I h,- )DDl r .si, ufS ';t,')ti-i a(J: .*arcd T') tic cnsiderably" less e:':',-, tire .r. redf.., :r.E !arr, '.
ap l ri that th, ri sidue present durir the second w,'.-k after a: :j.i-
( n.i s a' ir d: a -d by a ( m :i,'rir n of the 2- and 3-week s a h',. '.es.


Literature Cited

( 1) r ..K i,. and Chisholm, R. I).
I'4. "Ih determination (,f DDT in soil. Ass ,. Off. Ar. ChE -..
Jour. 32: 781-786.

(2) Lehman, A. J.
lb49. Pharnmacological considerations of inr.sec ticides. Ass',
F od and Drug Off. Bul. 13: 65-70.














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