Results of tests with DDT against cotton insects in 1944

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Title:
Results of tests with DDT against cotton insects in 1944
Physical Description:
6 p. : ; 27 cm.
Language:
English
Creator:
Loftin, U. C
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C.
Publication Date:

Subjects

Subjects / Keywords:
Cotton -- Diseases and pests -- Control   ( lcsh )
DDT (Insecticide)   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

General Note:
Caption title.
General Note:
"E-657."
General Note:
"May 1945."
Statement of Responsibility:
compiled by U.C. Loftin.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030289627
oclc - 779844066
System ID:
AA00025115:00001

Full Text

May 1945 S'ATEI t'L 'i BAHdI E-657




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

RESULTS OF TESTS WITH DDT AGAINST COTTON INSECTS IN 1944

Compiled by U. C. Loftin,
Division of Cotton Insects

The results of tests!/ conducted with DDT (l-trichloro-2,2-bis-
(p-chlorophenyl)ethane) during 1944 for the control of insects attacking
cotton are briefly summarized in this paper. The DDT was obtained in two
forms--(1) 10 and 50 percent factory mixtures with pyrophyllite and (2) a
technical grade. The DDT-pyrophylllte mixtures were further diluted with
pyrophyllite to the desired strength or mixed with other insecticides, and
the technical DIDT was pulverized and mixed with sulfur in a local commer-
cial hammer mill. In the tests where more than one application was made,
the treatments were applied at 4- or 5-day intervals except as otherwise
indicated.

DDT in the formulations used was of no practical value for control of
the boll weevil (Anthonomus grandis Boh.) or the cotton leafworm (Alabama
argillacea (Hbn.)), and caused increases of the cotton aphid (Aphis
gossypii Glov.) and the common red spider (Tetranychus sp.). It was effec-
tive against the pink bollworm (Pectinophora gossypiella (Saund.)), the
bollworm (Heliothis armigera (Hbn.)), the cotton flea hopper (Psallus
seriatus (Reut.)) and several other mirids, the stinkbugs (Chlorochroa sayi
81 C. ligata (Say), Euschistus impictiventris Stal, and Thyanta custator
Sthe onion (Thrips tabaci Lind) and tobacco thrips (Frankliniellea
fusca (Hinds)), and the beet armyworm (Laphygma exigua (Hbn.)). The re-
sults against the pink bollworm were especially encouraging, since no
satisfactory insecticidal control for this insect was previously known.
There was no indication of injury by DDT to the cotton plant. Additional
work is needed on methods of formulation and application, especially for
concentrated sprays and means of preventing an increase of aphids.



!/The experiments at Tallulah, La., were conducted by R. C. Gaines,
M. T. Young, G. L. Smith, and G. L. Garrison; at Waco, Bryan, and Port
Lavaca, Tex., by K. P. Ewing, R. W. Moreland, E. E. Ivy, C. R. Parencia,Jr.,
and A. B. Beavers; at Brownsville and Raymondville, Tex., by A. J. Chapman,
L. C. Fife, R. L. McGarr, Ivan Shiller, C. A. Richmond, 0. L. Walton,
W. T.'Wellhouse, and Ignacio Moreno; at Presidio, Tex., by L. W. Noble,
J. C. Clark, 0. T. Robertson, and M. H. Hughs; at Tucson and the other
places in Arizona, by W. A. Stevenson, L. W. Sheets, J. M. Breazeale, and
William Kauffman.





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Boll Weevil

In cage and plot tests DDT dust was not o80 effective as calcium arse-
nate against the boll weevil.

In tests on caged plants the percent mortalities were as follows: At
Tallulah, La., 34 from 2.5 percent DDT, 48 from 5 percent DDT, 75 from 10
percent DDT, and 84 from calcium arsenate; at Waco, Tex., 9 from 2 percent
DDT and 16 from 10 percent DDT both applied at 16 pounds per acre, and 78
percent from calcium arsenate at 8 pounds per acre.- In plots at Tallulah
five applications of 5 percent DDT dust failed to reduce the weevil in-
festation below that of the checks. In another experiment the addition of
2.5 percent DDT to calcium arsenate did not increase the effectiveness or
produce so much cotton as the calcium arsenate treatment. In other field
tests at Waco, Bryan, and Port Lavaca, Tex., where DDT in pyrophllite or
mixtures of pyrophyllite and sulfur were used for other insects, the boll
weevil infestation was extremely low but was not appreciably reduced by
the DDT.

Cotton Leafworm

DDT was not effective against the cotton leafworm.

At the 4Waco laboratory the median lethal dosage of a water suspension
of DDT applied to the dorsa of fifth-instar leafworms was determined as
61.5 mg. per gram of body weight or 206 times as great as the median
lethal dosage of 0.299 mg. for the bollworm. In field tests 3 or more
applications of approximately 16 pounds per acre of 1, 2, 4, and 8 percent
DDT dust applied with hand dusters at Waco and 4 percent DDT dust applied
by airplanes at Bryan failed to prevent defoliation of plants. Field
plots at Tallulah were defoliated following 5 applications of 5 percent
DDT dust. At Presidio, Tex., where 8 to 10 heavy dust applications were
made for the pink bollworm, DDT gave considerable control of the leafworm,
particularly the smaller larvae. In tests at Waco cotton plants sprayed
6 times with a water suspension of DDT at the rate of 0.64 pound of the
active ingredient per acre-application caused a greater reduction of leaf-
worms than plants dusted with the same dosage, but neither treatment pre-
vented almost complete defoliation.

Cotton Aphid

DDT was not effective against the cotton aphid and seemed to cause
about the same increase in aphids as did calcium arsenate, under the condi-
tions of light aphid infestations that prevailed in 1944.

In field experiments at Tallulah, Waco, and Bryan, the aphid popula-
tions in plots dusted 3 to 6 times with DDT were about equal to those in
the plots similarly dusted with calcium arsenate. The addition of 2.5
percent DDT to the calcium arsenate used in an experiment at Tallulah
caused a greater increase in aphids than undiluted calcium arsenate or 5
percent DDT in pyrophyllite, but where 1 percent of nicotine was added to
the DDT-calcium arsenate the aphids were held in check. However, at





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Brownsville the aphid build-up in plots receiving 7 effective applications
of 10 percent DDT dust was significantly lower than in plots treated with
calcium arsenate or a mixture of calcium arsenate and DDT-pyrophyllite, and
at Presidio 10 applications of 10 percent DDT dust did not cause a damaging
aphid population to develop.

In a large-scale experiment at Waco sweeping records during the dust-
ing period showed that populations of ladybird adults and larvae were re-
duced about 67 percent in the DDT plot and 70 percent in the calcium arse-
nate plot. At Tallulah these predators were reduced about 75 percent in
the field plots dusted with 5 percent DDT and 83 percent in the calcium
arsenate plots.

Red Spider

Observations in plots at Tallulah and Brownsville dusted with DDT
indicated that red spiders were increased somewhat by the treatment but did
not become sufficiently abundant to cause damage.

Bollworm

DIDT was effective against the bollworm.

In tests on caged cotton plants at Waco dusts tested against the lab-
oratory-reared third-instar bollworms gave the following percent mortali-
ties: 84 from 4 percent DDT and 73 from a 1:1 mixture of basic copper
arsenate-sulfur, both applied at 16 pounds per acre, as compared with 62
from calcium arsenate, 65 from lead arsenate, and 66 from cryolite (88 per-
cent sodium fluoaluminate), each at 8 pounds per acre. In a similar series
of cage tests the percent mortalities resulting from various strengths of
DDTi dusted at 16 pounds per acre were as follows: 85 from 4 percent, 71
from 2 percent, 37 from 1 percent, and 25 from 0.5 percent. An equal quan-
tity of DIDT (0.32 lb. per acre) applied as a heavy poundage of a low con-
centration dust was more effective than a light poundage of a higher
concentration; that is, 32 pounds of 1 percent DIDT was more effective than
16 pounds of 2 percent, 8 pounds of 4 percent, or 4 pounds of 8 percent
DDT. Four percent of DDT in pyrophylllte was only slightly more effective
when used with calcium arsenate than when used alone. A spray application
(water suspension) of 0.64 pound of DIDT per acre did not kill so quickly as
the same amount applied as a dust but was nearly equal in effectiveness by
the fourth or fifth day. After four applications the residual effect was
slightly greater from the sprays than from the dusts. Water sprays at the
rate of 1.28 pounds of DDT per acre caused 100 percent mortality of third-
instar bollworms, at 0.64 pound of DDT 89 percent, at 0.32 pound 66 per-
cent, and at 0.16 pound 45 percent.

In a field experiment at Waco on 1/10-acre plots with four replicates,
two effective dust applications of DIDT at 16 pounds per acre-application
resulted in the following gains in pounds of seed cotton per acre: 148
from 1 percent DDT,; 154 from 2 percent, 238 from 4 percent, and 230 pounds
from 8 percent DDT. Calcium arsenate at the same rate per acre-application
gave a gain of 273 pounds per acre. The 4 and 8 percent DDT and the calcium
arsenate treatments were significantly better than the check.





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In a large-plot (unreplicated) experiment at Bryan four applications
of a 4 percent DDT-pyrophylllte dust at 16 pounds per acre-application gave
a gain of 736 pounds of seed cotton per acre in comparison with 688 pounds
from calcium arsenate at 15 pounds per acre-application.

Pink Bollworm

DDT is the most promising material that has been tested against the
pink bollworm.

At Presidio DDT, cryolite, and mixtures of the two were compared on
1/5-acre plots with four replicates in randomized blocks. (There were
originally six replicates, two in each of three fields, but one was flooded
on August 23, after five applications had been made, and was dropped from
the experiment. The other two fields were flooded on September 13 after
eight applications and no yield records were obtained.) Dust applications
of approximately 15 pounds per acre were started when the oldest bolls were
large enough for the pink bollworm to attack, and were repeated at approxi-
mately 5-day intervals. The percent reduction in the larval population in
the bolls after eight applications was 53 from 2.5 percent DDT, 78 from
5 percent DIM, 88 from 10 percent DIDT, 62 from DDT-pyrophyllite-cryollte
(2.5:22.5:75), 61 from DDT-pyrophyllite-cryolite (5:45:50), and 44 from
cryolite alone.

In another test at Presidio a 6-acre field was dusted with 10 percent
DDT at 15 pounds per acre beginning on August 29 when 35 percent of the
bolls were infested. Dusting was discontinued on 21 acres of this field
on September 16 after 4 applications had been made, but was continued on
31 acres until 8 applications had been made by October 12. On this date
there was an average of 12 pink bollworms per green boll in the check, 8.3
per boll, or a reduction of 31 percent in the part receiving 4 applications
and only 0.73 pink bollworm per boll, or a reduction of 94 percent, after
8 applications. Late bolls in the section of the field dusted 8 times were
not damaged sufficiently to affect the grade of the cotton, whereas in the
check they were severely damaged.

In tests at Brownsville where moths were caged on plants heavily dusted
with DDT, no larvae developed in the bolls. In similar tests with smaller
dosages of 5, 10, and 20 percent DDT applied at the rates of 5/8 to 3
pounds of the mixture per acre, the reduction in larvae ranged from 25 to
81 percent. Small larvae crawling over a dust film of 10 percent DDT were
extremely irritated but not killed, indicating that the reduction in popu-
lation might have been due to killing the moths before oviposition occurred.

Cotton Flea Hopper

DDT was effective against the cotton flea hopper. Several concentra-
tions and combinations of DDT were compared with sulfur and the standard
1:2 mixture of calcium arsenate and sulfur for control of this insect.

At Port Lavaca, on heavily infested plots dusted five times at the
rate of 12 to 13 pounds per acre, 2 percent DIT gave a reduction in






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population about equal to that given by the 1:2 calcium arsenate-sulfur
mixture, but the yields were significantly better than from this mixture,
or from either 1 or 0.5 percent DDT.

At Raymondville and Brownsville, on heavily infested plots dusted once,
the reduction in flea hopper populations in 4 to 6 days was about one-third
greater from 2.5 and 5 percent DDT than from sulfur or 1:2 calcium arsenate-
sulfur. The DDT also held down the populations for a longer period,indicat-
ing that the interval between applications of this material might be
lengthened.

At Waco medium to heavily infested plots dusted four times showed no
significant differences in population between 4 percent DDT-pyrophyllite,
2 percent DDT-pyrophyllite, DDT-pyrophyllite-sulfur (2:18:80), calcium
arsenate-sulfur (1:2), and DDT-pyrophyllite plus (1:2) calcium arsenate-
sulfur (2:18:80). The yield from each treatment was greater than from the
check, and from the 2 percent DDT-pyrophyllite significantly greater than
from the calcium arsenate-sulfur but not significantly better than from the
other treatments containing DDT.

Plant Bugs and Stinkbugs

DDTYf was effective against plant bugs and stinkbugs.

In tests on caged plants at Mesa, Ariz., 2.5, 5, and 10 percent DDT
gave excellent kill of the mirids Lygus oblineatus (Say), Lygus spp.,
Adelphocoris superbus (Uhler), and Creontiades femoralis Van Duzee, and the
stinkbugs Chlorochroa sayi Stal, C. ligata (Say), Euschistus impictiventris
Stal, and Thyanta custator (F.). A high mortality of tarnished plant bug
(Lygus oblineatus (Say)) adults was also obtained with the same materials
in cage tests at Tallulah, La.

In field tests the results against the tarnished plant bug were some-
what erratic and control was not so consistent as in the cage tests. Con-
trol of mixed populations of the tarnished and rapid plant bugs (Adelphocoris
rapids (Say)) in field plots at Tallulah was poor in most instances from
six dust applications of 2.5 or 5 percent DDT. Field tests in Arizona in
which DDT was applied by hand dusters, power dusters, and airplanes at
weekly intervals for control of mixed populations of several species of
plant bugs and stinkbugs indicate that DDT-pyrophyllite-sulfur dust will
give better results than the arsenicAl-sulfur mixtures. In a small-plot
Latin-square experiment dusted with hand guns at Mesa, seven applications
of DDT-pyrophyllite-sulfur (4:36:60) resulted in a gain of 1,018 pounds of
seed cotton per acre, or 42 percent more than the check, as compared with
13 to 26 percent from four arsenical-sulfur mixtures. At Litchfleld Park,
Ariz., a heavily infested 18-acre field dusted six times by airplane with
DDT-pryophylllte-sulfur (4:36:60) produced a gain of 920 pounds of seed
cotton per acre, or 97 percent more than the check and 30 percent more than
an adjacent 58-acre field dusted with paris green-sulfur (15:85). At
Marana, Ariz., a lightly infested 20-acre field dusted once by airplane
late in the season with 2 percent DDT produced 17 pounds of seed cotton per
acre less than the 20-acre check. At Buckeye, Ariz., three heavily infested




UNIVERSITY OF FLOR DA
11 I I I, lll ,,, II II I'1
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1-acre plots dusted seven times with DYIT by power duster produced 551
pounds gain as compared with 396 rounds from paris green-sulfur (7.5:92.5),
and a los8 of 22 pounds from 1 percent dinltro-o-creeol. The dust used in
this experiment contained 2 percent of DDT in pyrophyllite for two applica-
tions, DDT-pyrophyllite-sulfur (4:36:60) for three applications, and 5 per-
cent DDT-pyrophyllite for two applications. Cage and field tests indicate
that 2 percent DDT was not so effective as 4 or 5 percent DIT and the addi-
tion of sulfur to the DDT dusts caused a quicker kill of plant bugs and
stinkbugs.

Thrips

In small-plottests at Brownsville for control of Thrips tabaci Lind.
on onions, the population was significantly reduced 24 hours after treat-
ment with 2.5, 5, and 10 percent DDT dust applied at rates from 0.21 to
1.70 pounds of DDT per acre. While the population decreased with the
increase in quantity of DDT applied, there was no significant difference
in the reduction obtained when 0.50 pound or more per acre was used.

In small-plot tests conducted in 1943 one application of a 3 percent
DDT dust gave very good kill of a heavy infestation of Thrips tabaci Lind.
and Frankliniella fusca (Hinds) on cotton.

Beet Armyworm

In tests on caged plants at Tucson and Mesa, Ariz., 2 percent DDT
gave excellent results against the beet armyworm.

Small D]rkling Beetle

In one cage test at Tucson, Ariz., 100 percent kill of Blapstinus
auripilis Horn was obtained in 67 hours with 2 percent DDT.