Progress Report Series No. 88
Agricultural Experiment Station
AUBURN UNIVERSITY
2. V. Smith, Director
Auburn, Alabama
INSE,1
Area
affect
applie
Ins
A nfhr
EFFECT of SEVERAL INSECTICIDES
and APPLICATION SCHI-IEDULES on
COTTON INSECT CONTROL
T. F. WATSON,
1 
F. S. ARANT,
1 
W. G. EDEN,
2 
and M. GSCONYERS,
CT PESTS are generally present in the Wiregrass season; (2) at pinhead square stage and thereafter
of Alabama in sufficient numbers to seriously for boll weevils and bollworms; and (3) for boll
yields of cotton unless control measures are weevil and bollworms as needed. In 1962 
through
ad. 1964 this procedure was modified 
slightly and insec-
ects of primary importance are the boll 
weevil, ticides were compared 
at six different application
o),sn(VYIQ radi.v B~ hmA .. the br.llworm He- schedules.
liothis zea (Boddie); and the tobacco budworm, H.
virescens (Fabricius). Hereafter in this report both
species of Heliothis are referred to as bollworms.
Other arthropods that have been implicated as
serious cotton pests are: several species of thrips; the
cotton aphid, Aphis gossypii Glover; the cotton flea-
hopper, Psallus seriatus (Reuter); and spider mites,
Tetranychus spp. Information gained through re-
search during a number of years, however, has shown
that these pests are of minor importance and rarely
occur in sufficient numbers to adversely affect cotton
production, (1) (4).
Experiments were conducted at the Wiregrass
Substation, Headland, Alabama, from 1961 
through
1964 to determine the effectiveness of several insecti-
cidal mixtures against the boll weevil and bollworms.
In 1961, emphasis was placed primarily upon appli-
cation of the following control measures: (1) full-
SDepartment of Zoology-Entomology, Agricultural Experiment
Station.
2 Resigned.
1. Wiregrass 
Substation.
METHODS AND MATERIALS
1961 Experiment. The experimental design was
a randomized complete block and each treatment
was replicated 4 times. Each plot was 16 rows wide
and 200 feet long. Data were collected from the
center area of each plot.
The experiment involved control of plant bugs,
fleahoppers, leafhoppers, thrips, bollworms, and boll
weevils. Plant bug, fleahopper, and leafhopper in-
festation counts were made on selected treatments
June 27 and July 3, 10, 
and 19. These populations
were determined by making 10 sweeps with a stand-
ard insect net in the center part of each plot.
Thrips population counts were made on selected
treatments May 29, June 7, 13, 27, and July 3 from
20 plants that were pulled at random from each plot.
The plants were put into 
1
/-pint fruit jars containing
200 ml. of water to which had been added a few
drops of formaldehyde. In the laboratory, 2 grams
of ordinary detergent were added to each jar and the
jar was shaken vigorously 
for 2 minutes. The jar 
top
-I
July, 1965
was replaced with screen wire through which the
liquid was poured, leaving 
the plant tissue in the
jar. The detergent solution containing thrips was
poured through a piece of thin nylon stretched over
an embroidery ring. The contents of each jar were
washed five more times with water and the washings
were strained through the embroidery ring. The
nylon was placed under a binocular microscope and
the thrips were counted. Standard square- and termi-
nal-count methods were used during the fruiting
period to determine population levels of boll weevil
and bollworms, resplectively.
All sprays were applied as emulsions with a high-
clearance, self-propelled spray machine. Sprays be-
fore June 26 were applied with one nozzle per row
at 40 p.s.i. pressure, which delivered 2 gallons of
finished spray per acre. On June 26 and thereafter,
sprays were applied with three nozzles per row at 6
gallons finished spray per acre. Rates of insecticidal
concentrates applied corresponded with recom-
mended rates, beginning with minimal amounts and
increasing as insect population pressure increased.
1962-64 Experiments. The experimental design
was a randomized complete block and each treat-
ment was replicated four times. Each plot was 16
rows wide and 150 feet long. Data were collected
from the center 100 feet of the 8 center rows. Analy-
ses of the data were made by the Department of
Research Data Analysis and the Computer Labora-
tory.
Insect infestations were assessed at weekly inter-
vals. Thrips (undetermined species) and cotton aphid
population levels were sampled during the early
stages of plant growth by vigorously beating young
plants over a funnel and allowing the insects to fall
into a vial of alcohol attached to the base of the
funnel. Standard square- and terminal-counts were
made throughout the major fruiting period to as-
certain population activity levels of boll weevil and
bollworms.
Nineteen treatments were included in the experi-
ment. These were comprised of three recommended
insecticidal mixtures, each applied on six different
schedules, plus an untreated check. Emulsifiable con-
centrates were diluted with water and applied with
a high-clearance, self-propelled spray machine..
Early-, mid-, and late-season rates were applied with
1, 2, and 3 nozzles per row, respectively. This re-
sulted in approximately 2.5, 5.0, and 7.5 gallons of
finished spray, respectively, being applied per acre.
However, the amount was varied slightly from year
to year.
Insecticidal mixtures used in these experiments
were toxaphene-DDT, endrin-methyl parathion, and
Guthion?-DDT [Guthion - 0,0-dimethyl S- (4-oxo-
1,2,3-benzotriazin-3 (4H) - ylmethyl) phosphorodi-
thioatel. Generally, three rates of each material
were used during the season, beginning with the
minimum, recommended and increasing as the pres-
sure from pest species increased.
The six application schedules employed in this
series of experiments were as follows:
(1) full-season insect control, i.e., insecticides
were applied on an automatic weekly schedule be-
ginning with the two-leaf stage. Later, the interval
was shortened to a 4- to 5-day schedule and con-
tinued until the cotton was mature.
(2) early-season insect control plus an automatic
4- to 5-day schedule after boll weevils had punctured
10 per cent of the squares. Beginning with the two-
leaf stage, three applications of insecticide were
made at weekly intervals; thereafter, none was ap-
plied until the automatic 4- to 5-day schedule was
initiated at the 10 per cent boll weevil level.
(3) automatic 10' per cent schedule, i.e., no insecti-
cides were applied until boll weevils had punctured
10 per cent of the squares; thereafter, applications
were made on a 4- to 5-day schedule until the bolls
were mature.
(4) ten per cent schedule and as needed, i.e., the
spray programs were initiated when 10 per cent of
the squares were punctured by boll weevil; applica-
tions were continued thereafter as needed to hold
infestation levels at or near 10 per cent.
(5) automatic 25 per cent schedule, i.e., no in-
secticides were applied until 25 per cent of the
squares were punctured by boll weevil; thereafter,
applications were made on an automatic 4- to 5-day
schedule.
(6) twenty-five per cent schedule and as needed,
i.e., the initial application was made at the same
time as the automatic 25 per cent schedule; subse-
quent applications were made only as necessary to
hold the boll weevil infestation at or near the 25 per
cent level.
DISCUSSION AND RESULTS
Minor insect pests were of little or no consequence
in this series of experiments. Thrips were not suf-
ficiently abundant to cause noticeable plant damage.
Spider mites, aphids, plant bugs, fleahoppers, and
leafhoppers were not important in these experiments
during the 4-year study. Only one small localized in-
festation of spider mites was observed and one ap-
plication of an acaricide (demeton) eliminated this
infestation.
With regard to most of these pests, similar re-
sults have been reported from several areas of the
State, (1) (2) (4) (5). However, spider mites are
serious pests in many areas of the State during some
~___1 tm~e~ ayears. a
In 1963, aphids were abundant enough in un-
treated plots to cause severe stunting and malforma-
tion of plants. Injury caused by the early-season
aphid infestation was subsequently outgrown and
final yields failed to substantiate the need for control
of this infestation.
1961 Experiment. Bollworm eggs were prevalent
on cotton in late June and continued to be present
on untreated cotton for the remainder of the growing
season. The greatest numbers occurred from mid-
August to mid-September. Worm populations were
highest in the untreated cotton during the last 3
weeks of August. All treatments were significantly
effective in reducing bollworm populations below
that of the untreated check.
The mean seasonal boll weevil infestation on the
untreated check was 52.8 per cent, whereas infesta-
tions on all other treatments were significantly lower.
The lowest mean seasonal infestation, 18.5 per cent,
resulted from the toxaphene-DDT schedule begun
at the two-leaf stage. The data in Table 1 show the
TABLE 1. INCIDENCE OF BOLL WEEVIL INFESTATION RELATIVE TO
STAGE OF COTTON GROWTH, WIREGRASS SUBSTATION,
HEADLAND, ALABAMA, 1961-64
Plantin Date 10% 
Days from Days 
from
Year Planting infest, level planting to 10% level to
date reached 10 % level total harvest
No. No.
1961 May 19 July 21 63 128
1962 April 19 July 10 82 128
1968 April 10 July 24 105 90
1964 April 15 July 14 90 126
severity of the boll weevil problem in 1961 as com-
pared with that of the following 3 years. Because of
an extremely late planting season, a 10 per cent boll
weevil population developed only 63 days after the
cotton was planted. Therefore, the cotton was under
boll weevil attack during most of its major fruiting
period.
Yields resulting from all insecticidal treatments
were significantly greater than those from the un-
treated check, Table 2. Three materials were ap-
plied on a full-season basis. The highest yield was
produced from plots treated with Guthion-DDT.
Methyl parathion-DDT produced intermediate re-
sults, whereas toxaphene-DDT produced the lowest
yields. Yields from methyl parathion-DDT were not
significantly different from either of the other two
treatments, but there was a significant difference be-
tween Guthion-DDT and toxaphene-DDT. Compar-
able treatments of toxaphene-DDT, endrin-methyl
parathion, and endrin-methyl parathion-DDT, requir-
ing 17 applications, produced 1,969, 1,741, and 1,741
pounds of seed cotton per acre, respectively. These
yields were not significantly different from each other
or from the highest yielding treatment, Table 2. A
comparison of the four schedules in which toxaphene-
DDT was the insecticide common to all shows that,
as the number of insecticidal applications increased
from 17 to 22, the yield of cotton decreased from
1,969 to 1,412 pounds of seed cotton per acre,
Table 2.
TABLE 2. COMPARISON OF THE EFFECTIVENESS OF VARIOUS 
APPLICATION SCHEDULES AND INSECTICIDES AGAINST BOLL WEEVIL 
AND
BOLLWORMS, AND ON SUBSEQUENT COTTON YIELDS, WIREGRASS SUBSTATION, HEADLAND, ALABAMA, 
1961
Wevl nese
Treatment
Range of
insect.
rates
Lb.
Total Mean number
applicationstal 
bollworms per
applications 100 terminals
No. No.
Weevil infested
squares
Pct.
.-I -
Untreated check 0 6.3 52.8
Toxaphene, 2-leaf stage; Tox-DDT .75-.0
pinhead squares and subsequently 2.0-1.0
as necessary for worms and weevils' 3.0-1.5 
22 0.2 18.5
Toxaphene-DDT, begin at pinhead square, 2.0-1.0
continue as necessary for worms or weevils' 3.0-1.5 
20 0.2 19.4
Toxaphene-DDT, as necessary for worms
and weevils except 3-day interval 2.0-1.0
at migration
1  
3.0-1.5 18 0.3 
19.8
Toxaphene-DDT, as necessary for 2.0-1.0
worms or weevils 3.0-1.5 
17 0.2 19.5
Methyl parathion, 2-leaf stage; M.P.-DDT, .125-.0
pinhead squares and subsequently as .25-.5
necessary for worms or weevils' .5-1.0 
22 0.2 23.4
Endrin-methyl parathion, as necessary .2-.25
for worms or weevils
1  
.3-.375 17 0.1 33.4
Endrin-methyl parathion-DDT, as necessary .2-.25-.5
for worms or weevils
1  
.3-.375-.75 17 0.3 25.5
Guthion, 2-leaf stage; Guthion-DDT, at .125-.0
pinhead squares and subsequently as .25-.5
necessary for worms or weevils' .5-1.0 22 
0.3 21.8
LSD .05
' When bollworm populations reached 4 to 5 per 100 terminals and/or 10 per cent of squares 
were punctured.
Yield, seed
cotton per acre
Lb.
103
1,412
1,668
1,790
1,969
1,873
1,741
1,741
2,068
528
vv
1962-6J4, Three-year Experiment. Table I preseilts
the plalitingo dates, harx ('st (ites, aid 1 (ates XX l
boll1 weexA i ifestatini is fi rst riecd the 10( per ('('Iit
lex el. T1W Mo 0st se('le'' (LaMIiag Cii 5 &(1 1) \ 1)011
wcc\e ils wxas in 1964: sliglitl less (lailage XX as calisedl
ill 1962, and practicallx ione iii 196:3. Litic le : prec
seits tie iiieaili seasonail itoh weex in ifestationis for
ealch ii secticidal treaItilic(1it at in the 1ii itreatenl ehek.
Altho10g the scasoi tal iii testationi w Xas hlighil ill 196, 3
thil ili 1962, it eatisen I(55 (laivg to coittoii. Ii
196:_3. 1)11ll ee i i dstatioi I oceni rre-l later thii ill
either of ti i othecr xyears. Ill additioni, the eottol,itws
1laiite'l earllier. IThils, the sen in gix hligher intesta-
tioii ill 196") reslted fl-0oii a high lte-seasonl paplil-
tini I that bltilt lip oil etti ilafter. it passedi its major
fruiitiiig period anld hald fwrsyquares to piulietir.
lifestiltiot I coin its rix ('ii ill Tab~le 13 atre the scasoi a
iiecaiis of, ll irepliceationis f'oi cieli iiiSectieiill ti ett
111cl1it, retrardlless of appliciation sel ednl Ies.
\Ii . (ee I)X~e'xttxe tt INxi C Iiin M11 \ixtIIiM'S [(elt 13()1,1
\Vmc tie xi , SLB(IA10N HE-IM)
I tutatilttit,
w( k
'1 tteiIpjtite it 1)I )'
Pce. P P.1,t.
IS Is5 52.2 5().
10.) 9 22.7 1 49
19.2 271.2 25.6
i I.1 I 9. 15.-,
16. 2
21.0.
that the( expern men t xx as ill progre-ss. 11 tXX'cX r, boll -
XXoil I (liiiag' XX-ias most)t 5('X re ill 196:3, id m( nost oif
the (lalliage to etottol i (Iliirili 1 that \ ear XX-ias attrn itia-
ble to 1 tiIXX trms1. Talbl( 4 plrCe(its tihe iiieai (sci all
'Yic.ldl frot) tIE' \ aliots iiiseetieiill trittiiints f'or
each selli('(1 uk' are etimi )ici( ai 1( these x ie Ids arc'
ettnpar('( iii Table 5.. All hiiseetieidal trc'itti ii(i Its rc-
xxheii ettoi 
1
areld XXith the i(' iii ete( cheeck. There
Cotton at left received no insecticide. The yield was 1,186 pounds
per acre. Cotton in center photo received 24 applications of a
recommended insecticide in a full-season program. The yield was
2,650 pounds per acre. Cotton at right received 11 applications
N62(i 196:3 196 1 tie ,ttt
No NVo N\ft. Neo.
C1 i - c kI 1.1 :37 .0 9).S 19.4
Gxli i I 2. 18 6.8 .-1 .1
X~it ii i (\ tift ON Nl t i iw' Sciod i ill \0 (1 it]] pot ., \(-(
tS11 it',it tiittN po liii i sl~lrt \\a Ilixel I l6 6
S( I *tii1c
)I iclt o ft tic cftttti put it c i itid '1 'I tfil .
F ill\ ',t lol ,e 10t 2 52((i1 )
I I, it llt o2 l'l it
NU wduheet 2it , _6 .1 it
-'5' -aiii ftiC
clwtllt 2,297 it
at H i I lu cl I)II~ l~ It)
I Wjll
1, h. i
(1 1 ) i c
1 96 4
1I h.
1.0)5 i.
2.449) It
25)W 1)
') . i
t
S: 1) u , 192- Ii ) 512 it)
-5.5: it 2 1575 i) 2..56S it
' ), it): 1 ( -,511 1 t 2), 67 It
2,662 c 2, 195 1) 2, 4 94 I)
XXer' n)o sio-iiifieiit ilierecascs ill pr tdlietitoii iitiiigw
ixn of, t~e sehedilles. I Itix ex r. shlitiX\ iiiorc siecl
tttl\it s jprt)(lie(d b.\ the' 1( per ceititas i i('ed
sch('(l Iil('. r-e('i iiif lati ax oruetf 1_3 iniseeiei(Ial aj)-
plit.'atitlns. Othier tiati the( cec'k, the( maist aliiltt
of, 5('(d ttiti \X\as proit 1ic('( oil the plotts reeeci iig
full-scastii etmitiol iim retjii in alli ax (re of 2:3.7
ii isecticidtil appl icatiton s. Talte (6.
TI i':-xta iii (sti oritti I rix ealed thalt in secticidal
ti('atinil t XXias e's('itial at stlie tiiiin' di rio g thec
(Flt)Xxilt scasttii tot ettitrt)1 (itlher the bl)l XX ('e il, boll-
wX ti 1), tom 1bthm. All I histeticinlal treatiiiits re'suiltedl
iill x' 'sigrnificanlt " \i(l(I iiiei('ases XXhlil comtiipared
wXith~ the tii r(at('d cl ('ek, Tal e 7. 1 ItXX (\c(r, (lit-
of the same insecticide, beginning when 25 per cent of the squares
were punctured. The yield was 2,523 pounds per acre. iThere
was no significant difference between the two control schedules).
Applications
1
1962 1963 1964
No. No. No.
Mean
No.
Full-season 24(2) 24 23 23.7
Early-season + 10% ............. 17(3) 16(1) 16 16.3
10%-automatic schedule- 14(3) 13(1) 13 13.3
10 %-as needed .................. 14(3) 12(1) 13 13.0
25 %-automatic schedule.--- 11(4) 11(3) 8 10.0
25 %-as needed 11(4) 10(3) 8 9.7
SNumbers in parentheses indicate the number of DDT ap-
plications made for bollworm control prior to buildup of the
indicated boll weevil infestation levels. The numbers preceding
the parentheses denote the number of applications of insecticide
mixture exclusive of applications of DDT alone.
TABLE 7. AVERAGE YIELD OF SEED COTTON OBTAINED FROM
THREE INSECTICIDAL TREATMENTS AND AN UNTREATED
CHECK, WIREGRASS SUBSTATION, HEADLAND,
ALABAMA, 1962-64
Yield of seed cotton/a. and significance
1
Treatment
1962 ,1963 1964 Mean
Lb. Lb. Lb. Lb.
Check 1,186 a 1,644 a 1,035 a 1,288 a
Toxaphene-DDT 2,471 bc 2,403 b 2,435 b 2,436 b
Endrin-M.P ........ 2,302 b 2,677 c 2,377 b 2,452 b
Guthion-DDT .... 2,515 c 2,570 bc 2,701 c 2,595 c
1Yields followed by the same letter are not significantly different
at the 1% level. Duncan's (3) Multiple Range Test.
ferences occurred among the insecticidal mixtures
used. In 1962 and 1964, when both boll weevil and
bollworms caused economic damage, higher yields
were obtained from the Guthion-DDT mixture; toxa-
phene-DDT treatments resulted in intermediate
yields; lowest yields were obtained from the endrin-
methyl parathion treatments. In 1963, however,
when bollworms caused most or all of the yield
losses, the endrin-methyl parathion treatments re-
sulted in the highest yields, followed by the Guthion-
DDT and toxaphene-DDT treatments.
When results of all 3 years were combined and
analyzed, the yields of seed cotton from the Guthion-
DDT treatments were significantly higher (1% level)
than yields from treatments of endrin-methyl para-
thion or toxaphene-DDT. There was no difference
between yields of the latter two treatments.
SUMMARY
The only insects causing serious damage to cotton
in the Wiregrass Area of Alabama during the 4-year
period of 1961 through 1964 were boll weevil and
TABLE 6. NUMBER OF INSECTICIDAL APPLICATIONS REQUIRED ON
VARIOUS SCHEDULES, WIRECRASS SUBSTATION, HEADLAND,
ALABAMA, 1962-64
Schedules
Check
bollworms. The investigation reported here revealed
that insecticidal treatment was essential at some time
during the growing season to control these pests.
Control during the major fruiting period was of
greatest importance. Yields of cotton were not in-
creased by control of minor pests, such as thrips,
aphids, and fleahoppers.
In the full-season control program in 1961, the
Guthion-DDT treatment resulted in the highest
yield; methyl parathion-DDT was intermediate; and,
toxaphene-DDT was lowest. Schedules of toxaphene-
DDT, endrin-methyl parathion, and endrin-methyl
parathion-DDT treatments requiring 17 applications
resulted in comparable yields to methyl parathion-
DDT applied on a full-season program. A compari-
son of four toxaphene-DDT programs, ranging from
17 to 22 applications, showed that as the number of
insecticidal applications increased, yields decreased.
In 1962-64, six application schedules were evalu-
ated in the tests to determine the best control pro-
gram to follow. Of the application schedules evalu-
ated (programs ranged,.from full-season control to
those begun only after 25 per cent of the squares
were punctured by the boll weevil) the full-season
schedule resulted in the lowest yields. Highest yields
occurred in the 10 per cent schedules.
Three currently recommended insecticide mixtures
were evaluated at each application schedule. All
resulted in significantly (1 per cent level) more cot-
ton than was produced in the untreated check. How-
ever, the Guthion-DDT treatment resulted in higher
yields (1 per cent level) than either endrin-methyl
parathion or toxaphene-DDT. There was no statisti-
cal difference between the latter two mixtures.
LITERATURE CITED
(1) ARANT, F. S., Cotton Insects and Their Control with
Insecticides. Auburn University Agricultural Experiment
Station Circular 106. 1951.
(2) Cotton Insects can Cost State's
Growers $50 Million in a Single Year. Highlights of
Agricultural Research Vol. 2, No. 2. Auburn University
Agricultural Experiment Station. 1955.
(3) DUNCAN, D. B., Multiple Range and Multiple F Tests.
Biometrics 11: 1-42. 1955.
(4) WATSON, T. F., Influence of Thrips Control on Cotton
Yields. Journal of Economic Entomology. (in press).
1965.
(5) WATSON, T. F., and Sconyers, M. C. Comparison of
Insecticide Application Schedules for Control of Cot-
ton Insects. Journal of Economic Entomology. (in
press). 1965.