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STATE PLANT BOARD
December 1949 E-792
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
EARLY-SEASON APPLICATION OF INSECTICIDES
FOR COTTON-INSECT CONTROL-i
By K. P. Ewing and C R. Parencia, Jr.,
Division of Cotton Insect Investigations 2/
Experiments in early-season application of insecticides for cotton-
insect control conducted on a community-wide basis in Wharton County,
Tex., in 1948 (Ewing and Parencia 1949) were so successful that some-
what similar experiments, but on a smaller scale, were conducted in
central Texas, near Waco, in 1949.
Some of the experiments were also designed (1) to determine whether
cotton that receives early-season treatment only can mature a full crop
without late-season treatment for the bollworm, and (2) to compare the
effectiveness of sprays and dusts in controlling cotton insects.
The boll weevil (Anthonomus grandis Boh.) is a serious pest of cotton
almost every year in central Texas, especially in river and creek
bottoms and in areas adjacent to woodlands and other hibernation quarters.
The cotton fleahopper (Psallus seriatus Reut.) and thrips (several species)
often cause considerable damage early in the season in this area. The
bollworm (Heliothis armigera (Hbn.)) is frequently an important late-
season pest and is the most dreaded and most difficult to control of all
/ Presented at the meetings of the American Association of
Economic Entomologists, held at Tampa, Fla., December 13-16, 1949.
2/ In cooperation with the Texas Agricultural Experiment Station.
3/ The authors acknowledge the valuable assistance of H. S. Johnson. Jr.,
and C. B. Cowan, Jr., Division of Cotton Insect Investigations, and of L. W.
Lee, McLennan County supervisor of the Farmers Home Administration.
Farmers in two communities cooperated--the Satin community in
Falls County and the Bolton Bend community in McLennan County. Both
communities are located in the Brazos River bottoms, where weevils
are known to have caused severe damage to cotton for many years.
In the entire Bolton Bend area, there are 19 farms, all purchased by
their present owners through the Farmers Home Administration. How-
ever, all farmers in this entire area did not cooperate in the insect-
control progaifn, only the farmers in the western part of the area.
Therefore, for the sake of specific identification of the participants, the
Bolton Bend community includes only the adjoining farms in the western
part of the area that received early-season applications of insecticides.
A total of 350 acres in the eastern part of the area received no treat-
ment for insect control at any time during the season, and this cotton
was a source of weevils for the reinfestation of the early-treated cotton.
There were 1,400 acres of cotton that received treatment, 700 in
each community. Of this total, 380 acres were planted early(in April),
and the remainder was planted late (around the middle of May or later).
The early-planted cotton received two treatments and the late-planted
cotton one treatment. To obtain the maximum amount of information on
maturity of the cotton before bollworms appeared, and the need, if any,
for bollworm control, detailed seasonal records were made in the early-
Comparable check areas, also located in the Brazos River bottoms,
were utilized. There were two check areas for the early-treated area
of the Bolton Bend community; one received late-season treatments,
and the other was untreated throughout the season. The seven late-
treated check fields received an average of 3.5 insecticidal applications
between July 1 and 25. The check fields of the Satin community were
untreated throughout the season.
A total of 380 acres of early-planted cotton in 19 fields on 6 farms
received two early-season treatments of one of the new all-purpose
insecticides. In some of the fields sprays and dusts were both used
In the Bolton Bend community two dusts were used. The active
ingredients were as follows: (1) 20 percent of toxaphene plus 40 per-
cent of sulfur, and (2) 5 percent of DDT plus 40 percent of sulfur plus
sufficient gamma benzene hexachloride to give 3 percent of the gamma
isomer in the finished dust. One field was sprayed with a toxaphene-
In the Satin community the fields were subdivided so that four were
dusted and four were sprayed. Three dusts were used. The active
ingredients were as follows: (1) 20 percent of toxaphene plus 40 percent
of sulfur, (2) 10 percent of DDT plus 40 percent sulfur plus gamma
benzene hexachloride sufficient to give 2 percent of the giamnma isomer
in the finished dust, and (3) 10 percent of chlordane plus 5 percent of
DDT plus 40 percent of sulfur. The emulsion concentrates consisted of
(1) toxaphene, 6 pounds per gallon; (2) toxaphene and DDT, 4 and 2 pounds
per gallon, respectively; and (3) chlordane and DDT, 4 and 2 pounds per
The dusts used during early-season treatments were applied by 6- or
8-row ground machines. The rate of application was approximately 10
pounds per acre. Late-season applications were at the rate of about 15
pounds per acre.
The sprays were applied by 6- or 8-row tractor attachment machines.
The total volume of spray used in the early treatments was 2 1/2 gallons
per acre, and it was applied at 60 pounds pressure with one nozzle per
row. One quart of the emulsion concentrate was used per acre. Late-
season sprays were applied at a rate of 7 1/2 gallons per acre with 3 nozzles
per row, and 3 pints of the emulsion concentrate was used per acre.
The average dates of treatments were May 31 for the first application
and June 8 for the second. Boll weevil hibernation records at Waco
duringthe past 10 years show that 93 percent of the weevils are out of
hibernation by June 5. Therefore, the applications were timed to kill as
many of the overwintered weevils as possible before they laid eggs. At
the same time, mid-season application of insecticides was omitted to
give beneficial insects time to increase in numbers sufficient to help
control the bollworm infestations that usually develop sometime between
July 10 and 25--average date July 20.
The procedure and methods of recording insect infestations and other
field data were essentially the same as had been previously reported in
the Wharton County experiments (Ewing and Parencia 1949).
Rains were frequent during the month of June and the first half of
July. From June 9 to July 15 rains fell on 18 days out of the 37. The
rainfall during June was twice the normal for that month, and the rainfall
for the first 15 days of July amounted to 51 percent more than the normal
for the entire month.
In spite of weather conditions during June and July being extremely
favorable for insect increases, excellent control was obtained of thrips,
fleahopi',-rs, and owvrwintered boll weevils.
Immediately prior to the first treatment there was a comparatively
high infestation of thrips, average of five per plant in both areas. This
insect had already stunted the growth of the plants and was causing con-
siderable deformity of them in some fields. Many plants had the appear-
ance of having been seared with a blow torch. All the insecticides gave
excellent control of thrips.
Within 4 or 5 days after the first application the plants showed a
marked recovery. During the 2 weeks following the first application
the treated cotton averaged one and one-fifth thrips per plant, and the
untreated cotton averaged six. Results from other experiments at Waco
in 1949 showed that, for complete protection against thrips, treatments
in the community experiments should have been started about 2 weeks
earlier, or about the middle of May.
While the fleahopper infestation was relatively light, this insect caused
some damage in most of the fields. The maximum initial infestation
(before treatment) in any field was 26 fleahoppers per 100 terminals. One
of the check fields averaged 22 fleahoppers per 100 terminals for the first
4 weeks that infestation records were made. All insecticides gave ex-
cellent control of the fleahopper.
Bollworm infestations developed to the point of causing questionable
damage in the early-treated fields of the Satin community about the
middle of July. These fields were then subdivided and a portion of each
field received two late-season insecticidal applications for bollworm
control, and the other portion was left untreated to see whether beneficial
insects would give control. (See table 1.) The boll injury averaged 4
percent in the late-treated cotton and 6 percent in the cotton that did not
receive late treatment. The yields per acre were 489 pounds of lint
from the cotton that received no late treatment and 536 pounds from the
late-treated cotton, a gain of 9.6 percent. These figures show that the
actual damage from bollworms was relatively light.
Since there was a fairly heavy infestation of bollworm eggs and
young larvae but only a light damage to bolls, beneficial insects were
undoubtedly present in sufficient numbers to give valuable assistance in
controlling the bollworm. This emphasizes the importance of proper
timing of the early-season treatments, that is, of stopping treatments
early enough to give beneficial insects plenty of time to build up again
before bollworms appear. This time interval should be at least 4 weeks,
and more if possible.
Table 1.--Yield of lint cotton (pounds per acre) in fields receiving late
applications and no late applications of sprays and dusts for boll worm
control, following two early-season applications for control of other
cotton insects. Satin community.
Kind and time of application Field 1 Field 2 Field 3 Field 4 Ave:rage
Late treatment 593 591 424 521 532
No late treatment 540 600 375 455 493
Average 566 596 400 488 512
Late treatment 594 597 420 553 541
No late treatment 542 584 336 476 484
Average 568 590 378 515 513
Average of dust and spray:
Late treatment 593 594 422 537 536
No late treatment 541 592 356 466 489
Immediately before the first treatment there were medium to heavy
infestations of boll weevils in every field of cotton in the two communities.
The initial infestations averaged 178 weevils per acre in the cotton that
was to be treated and 114 in the check fields.
Two weeks after the first treatment, 2 percent of the squares in the
treated and 34 percent in the untreated cotton were weevil-punctured.
For 4 weeks after the second treatment the weevil infestation remained
extremely low in both treated communities. The average weevil infesta-
tion for the season (June 12 to July 29) was 11 percent in the treated and
42 percent in the untreated cotton. (See table 2.)
The two early-season applications of insecticides gave satisfactory
seasonal control of the boll weevil in 13 of the 19 fields. Four fields
received two late-season applications for weevil control, one field
received one, and one field three. These fields were all in the Bolton
Bend community. They were adjacent to or near undusted cotton and
were subjected to more weevil migration than other fields. The treated
cotton in the Satin community had more buffer area immediately surround-
ing it and needed no late-season treatments for weevils.
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The treatt-d co' ,n reta; -d its early -,'rurs and began f-t'ui ;
heavily several week( earlier .. the untria cotton It wa read
for harvest approximately 3 weeks earlier.
The- seasonal average number of blooms per acre was 1,'M i4 l it!
untreated fields and 4,201, or slightly more than four times as many,
in the treated.
In the early-season applications both sprays and dusts gave approx-
imately 100 percent control of all insects present, such as thrips, flea-
hoppers, and boll weevils. One field with cotton in the presquare stage
had 145 weevils per acre on the day before the first spray: treat i t.
Infestation records made 24 hours after treatment showed no weevils,
or 100-percent control. In fact, records were made eve!. 24 hours in 7
of the 11 fields in the Bolton Bend community, 6 of which had been dust-d,
and each of them showed 100 percent kill of overwintered weevils, -.uch
results would be expected, since weevils are killed more easily while
cotton is in the presquare stage or while they are feeding on the outside
portions of the plant than after they have begun feeding in-ide the squares
Table 1 shows that sprays and dusts were.- equal in their effectiv.i'rss
against all insects.
In the two communities the average production of lint c otton p(r acre
was 178 pounds from the untreated and 415 pLuirnds from the treated
cotton, a gain of 133 percent. (St-e figu.ires 1 and 2.) The profitt after
deduction of all expenses of poisoning, picking, and gli;.1i w,,- .}i4.42
All adjoining fields of cotton in two communities near Waco in c entri al
Texas were dusted or sprayed with two early-season applications f one
of the new all-purpose insecticides for control of cotton insects. Detail 1
seasonal records were made in 380 acres, or 19 fields, of early-planted
cotton, in order that information might be obtained on maturity of early-
treated cotton before bollworms appeared.
There were heavy infestations of thrips, light to medium infestations
of cotton fleahoppers (Psallus seriatus Reut.). and medium to hea- v
infestations of overwintered boll weevils (Anthonomus grandis Boh.)
in every field. Rainy weather in June and July was favorable for insect
multiplication, especially for weevils.
1 Ie two early-season (about May 31 and June 8) applications of
insecticides gave satisfactory seasonal control of the boll weevil in 13
of the 19 fields. The average seasonal infestation was 11 percent in the
treated and 42 percent in the untreated cotton. The fields that needed
late-season treatment for boll weevils were adjacent to or near un-
Two late-season treatments for bollworm control were made in four
fields. The increased production from control of the bollworm (Heliothis
armigera (Ibn.)) was only 9.6 percent. In most fields a full crop of
cotton was produced before bollworms appeared. The importance of
stopping treatments early enough to give beneficial insects time to build
up again is thus emphasized. This interval should be 4 weeks or more.
There was a seasonal average of four times as many blooms in the
treated as in the untreated cotton. The early-season treatments hastened
the fruiting and maturity of the cotton by approximately 3 weeks.
The average production of lint cotton per acre in the two communities
was 178 pounds from the untreated and 415 pounds from the treated
cotton, a gain of 133 percent. The net profit was $54.42 per acre.
The low-gallonage, low-pressure sprays gave insect control equal
to that given by the dusts. The average yields were 512 and 513 pounds
of lint cotton per acre from sprayed and dusted fields, respectively.
Ewing, K. P., and C. R. Parencia, Jr.
1949. Experiments in early-season application of insecticides for
cotton-insect control in Wharton County, Tex., during 1948.
Bur. Ent. and Plant Quar. E-772.
Figure 1.--Field of cotton in Satin Community--W. D. Walker farm--
showing benefits of insect control. This field received early-season
insecticide applications on May 31 and June 8 and late-season appli-
cations on July 18 and 23. It was ready for picking by August 15,
and the yield was 594 pounds of lint per acre.
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Figure 2.--Field of cotton in the untreated area--Warner farm--showing
severe insect damage, mostly from boll weevils. This field was typical
of this untreated area which produced 178 pounds of lint cotton per acre.
UNIVERSITY OF FLORIDA
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