Results of field experiments with DDT against insects affecting tomatoes in Southern California

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Material Information

Title:
Results of field experiments with DDT against insects affecting tomatoes in Southern California
Physical Description:
8 p. : ; 27 cm.
Language:
English
Creator:
Wilcox, Joseph, 1901-1982
Howland, A. F
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
United States Department of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
DDT (Insecticide) -- Field experiments   ( lcsh )
Tomatoes -- Diseases and pests -- California, Southern   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Additional Physical Form:
Also available in electronic format.
Statement of Responsibility:
by Joseph Wilcox and A.F. Howland.
General Note:
Caption title.
General Note:
"E-699."
General Note:
"August 1946."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030292288
oclc - 780059029
System ID:
AA00026069:00001

Full Text



August 1946 E-699

United States Deprtmrent of Agriculture
Agricultural Research Administration
Bureau of iEntomology and Plant Quarantine

R&oULTS OF FIELD EXPiRItII.7.T3 V.TH DDT AGAINST Ii OCT. XF'FLCTI Cr
TOLATCES IN SOUTHERN CALIFORNIA

By Joseph Wilcox and A. F. Howland,
Division of Truck Crop and Garden Insect Investi- .ions

Tomato plants and fruits are attacked commonly in .;uthern
California by several species of insects and related pests. I.,.-
more important are the tomato fruitworm (Heliothis ar1Lqrd r,.- '.)
the tomato russet mite (Phyllocoptes destructor Keifer), thY '....'
hornworm (Protoparce quinquemaculata (Haw.)), the tobacco. hon
(P. sexta (Johan.)), the beet armnyworm (Laphygma exia ( ..)),
and several species of cutworms which feed on the young p-,.s
on the fruits during the fruiting stage, including the 'ia.-d
cutworm (Peridroma margaritosa (Haw.)) and the gran-iu.ate ciruco.
(Feltia subterranea (F.)). The tomato pinworm (Keiferia l ...
sicella (Busck)), which was formerly a serious pest of trmatoe- in
southern California, was present in very small numbers inr this
locality during the 1944 and 1945 seasons.

Tomato Fruitworm Tests

Use of Hand Dusters.-Preliminary tests with dust mix..u' ..:r-
taining DDT, calcium arsenate, or cryolite were made against thL-
tomato fruitworm during 1944. The results of these tests were our-
marized by White l/. Additional tests were conducted during the 1905
season, and the results of the two seasons' work are shown in tab,.e 1.

The insecticides were applied with hand dusters to plots avi.-
aging about 0.035 acre in size (4 to 5 rows wide and 9 to 12 -lan!ts
long). In 1944 the tests were made in triplicate in each of four
fields, and in 1945 in quadruplicate in each of three fields. Thr.-e
applications were made, the first when the fruit of the iain crop was
setting and the second and third applications at 2-week intervals
thereafter. The dust was applied at the rate of 30p priu:I ,- c_
per application, making a total of 90 pounds per acre f '1., 1. :<.i.-.-r 7
The data on fruit damage and control were obtained by pi._:x c.'
examining all tomatoes from 5 plants taken at random from the i ,idl1
of each plot at the regular picking times throughout the .:.-.


7/ 'White, W. H. A summnary of the results of the wo" k with DDT con-
ducted by the Division of 'ruck Crop and Garden Inz, .t Inv.-, Li:;ations
during the season of 1944. U. S. 'Bur. E&t. and Plant Q &,r. i-6"42,
8 pp. 1945 [Processed.]






-2-


Table 1.-Results of insecticide applications with hand dusters
for the control of the tomato fruitworm


1944 1945
Insecticide _______________________
(Figures in percent) Damage I Control DamageI Control

Percent Percent Percent Percent

Cryolite 70, sulfur 22 7.7 57 3.7 59

Calcium arsenate, undiluted 7.4 59 -

DDT:
2.5 3.9 78 1.6 82

5 2.9 84 1.7 81

10 .9 95 .6 93

20 .3 97

DDT 4 fused with sulfur 85 1.1 88

DDT 10 fused with sulfur 85 .4 96

Check (no treatment) 17.9 9.1 -


I/ References to percentage of cryolite, unless
otherwise, indicate the percentage of sodium
aluminate.


stated
fluo-


2/ Mixed with pyrophyllite only in 1944; mixed with
pyrophyllite and sulfur 25% in 1945.










The results obtained in 1944 i.' al
were superior to cryolite and .a ,
gressive increase in control was appar-'i- the t
creased from 2.5 to 10 percent, a '.
10-percent strength. In 1945 the results ve
cept that there was no difference bet2ee
strengths of DEL.T In 1945 &:2L w.3 cn
percent "DD" riLL.t,. *i, .Lii, gave oJ,. a '
increase in control over a 10-percer. i',x. a
of DDT fused with sulfur, which -a,,1- _
improved control over s5i(i-l-lar ,o ,.'-j rials ,

In 1945 another series of experinm: 's
fields, e.:.--h in quadruplicr.ie. A ."
DDT, 25 percent of sulfur, and 65 ;
in each test at a total rate of 90 pound
but at different intervals of application,> ,
and at two ti.-s of !Dtat.in' the *Jilt
the main crop was e,.'inning to set, ad 'I"
worm infestation was low in all three fi", co
be considered as conclusive. The res'! indc';
applications made at intervals of 1 ,.-! 2 :s
made at 3-week intervals, :cnd that ..1.. ion
of the main crop was setting are superior to t".
later. In other viords, even with a .-.rior
good results cannot be obtained unless t. ..
at the right time and repeated at reLua.'' .
2 weeks.

Use of Power Dusters.-In other exper 's th
were applied with a 2-row power dutc o to pi. .
The plots were at least eight rows ".., K v ec
averaged from 0.5 to 0.8 acre in si...- i
licated four 'to ix times, and fruitwor,,.i e
determined as in the hand-dusted p,,. .'e
insecticide wctre made at 2-week irn,L-v...r
of the main crop was be.ri n.. -n- to <,.

In 1944 the experimental field %.
Calcium arsenate 70 percent plus suli' 25 ,
total rate of 125 pounds per acre, .
70 percent plus sulfur 22 percent, applied 23 :
gave 70 percent control; and DDT 5 percent, "
and applied at 131 pounds per acre, f-a, : '-
superior control given .y the 5-r ).:'n; over
of the other insecticides was highly E:-.:.i


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O i
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-4-


In 1945 similar tests were conducted in two fields, each con-
taining four replicate plots. The rates of application ranged from
101 to 125 pounds of the dust mixtures per acre for the three app-
lications. The results are shown in table 2. A 4-percent-, DDT mix-
ture was superior to the cryolite dust used, and lO-percnt DDT was
superior to the 4-percent mixture. DDT 4-percent fused with sulfur
was used in one field, but the results are not shown in table 2.
There was no significant difference between the two 4-percent DDT
mixtures.

Control of Cutworms, Hornworms, the Beet Ar-nrnrr:-m,
and the Tomato Russet Mite

In experimental plots for the control of the tornato fitworm,
infestations of insects other than the fruitworm occirred-, -
records were kept of the fruit damage caused by these inse *.. As
no separate experiments were conducted for the control of "1.'e,
insects, methods of checking results, rates of application, etc.,
were the same as previously described in the tomato fruil-k. .om
experiments.

Cutworms.-These insects were important in one field 3'- ing
the 1944 season, and the results in triplicate plots are shown in
table 3. DDT at 5 and 10 percent were both superior to !) Y 2,5
percent, to cryolite 70 percent, and to undiluted calcium arsenate,
the best control being obtained with the 10-percent DDT 6.rst mixture.

Hornworms.-Although hornworms are usually present in tomato
fields in southern California, the percentage of fruit a' huily
damaged by them is small, and the results given here are by no mineans
conclusive, since they are based on experiments in fields-with low
infestations. The results obtained in three fields, one in 1944
(triplicate, plots) and two in 1945 (8 replicated plots), are shown
in table 3. With the materials used in both 1944 and 1945 the av7r-
age percentages of control were as follows: 70 percent c:,'"ie, 48:
2.5 percent DDT, 66; 5 percent DDT, 72; and 10 percent DDT, 5. It
therefore appears that, in order to obtain a satisfactory --ee of
control of hornworms with DDT, a 10-percent dust should :

Beet Armyworm.-This insect caused severe damage to th tomato
fruiti -n several of the experimental fields during the 19/45 sescn.
The results obtained with power dusters are shown in table 2, V2-d
those with hand dusters in table 3. The best control w obtailn.-.:
with mixtures containing 10 percent of DDT and 25 per :.-' or more
of sulfur. It did not appear to make any appreciable differ-,'ce
whether the DDT was mixed with the sulfur or fused with o






-5-


Table 2.--Results of insecticide applications with power dusters
for the control of the tomato fruitworm and the beet
armyworm. 1945


STomato fruitworm I Beet armyworm
Insecticide I I
(Figures in percent) Damage Control Damage Control

Percent Percent Percent Percent

Cryolite 67.5, sulfur 25 6.4 47 12.3 46

DDT 4, volcanic ash 46,
sulfur 50 2.6 79 6.3 72

DDT 10, volcanic ash 40,
sulfur 50 0.9 93 0.8 97

Check (no treatment in
adjacent fields) 12.0 22.7 -














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Tomato Russet Mite.-- Obserwvtions made in one of the experimen-
tal fields in 1944 indicated that DDUT was of little or no value in
the control of this mite, but in 1945 good mite control was obtained
when 25 percent of sulfur was incorporated in the DDT dust mixtures
and applications were made as indicated for torato fruitworm control.

DDT Dar a;;e and Residue

In the experiments conducted in southern California during 1944
and 1945 on tomatoes with dust mixtures cont'.-: in as high as 20
percent DDT, and which totaled several hundred acres of field-grown
tomatoes, no injury to the plants or fruit nr,,; the use of DDT has
been observed.

Chemical analyses 2/ indicated that DDT residues dissipated
rapidly from the fruit out rather slowly from the leaves. These
tests showed also that wiping the fruit ..ith a cloth was a very
effective method of removing DDT residues.



In experiments in southern California during 1944 and 1945
it was determined that dust mixtures cont.itLi;:: 2.5 or 5 percent
of DDT gave about 80 percent control of the tomato fruitworm, and
were superior to previously recc;'L.-iended cryolite dust mixtures
containing approximately 70 percent of sodium fluoaluminate, and
to undiluted calcium arsenate. Dust mixtures containing 10 percent
of DDT resulted in approximately 94 percent control of the tomato
fruitworm, and were statistically superior to the v.eaker dilutions
Furthermore, a dust mixture containing 10 percent of DUT gave better
control against other caterpillars attacking tomatoes during the
fruiting stage, such as the tobacco hornworm, the tomato hornworm,
the beet armyworm, and several species of cutworms, than was ob-
tained with weaker dilutions of DDT or with 70 percent cryolite
dusts. Undiluted calcium arsenate was superior to 10-percent DDT
in the control of hornworms. DDT dust mixtures were not effective
against the tomato russet mite unless 25 percent of sulfur was
included as a diluent.

The tests during 1945 indi cated that dust mixtures containing
20 percent of DDT were not sufficiently superior to the 10 percent
strength to warrant the additional expend;,_. involved. It v'as in-
dicated also that at the strength tested (10 :,--cent) DJT fused with
sulfur was not superior to the customer, mechanical mixture of DDT
and sulfur.


2/ Analyses made by rLobert A. Fulton, Division of Insecticide
Investigations.




UNIVERSITY OF FLORIDA

3 1262 09238 7223


~i ;~ ~


obtainedi when three applications were made
- cppro-site>., 30 pounds per acre per app-
Scarted P-n the first fruit of the main
serior to z-, locations started 2 weeks


:i ..... or fruit was apparent from the exten-
Satoe in southernn California. DDT residues
.^o i;fc-h rar-idl- and were easily removed by