Miss Martin
CIRCULAR 51
MAY 1926
Dusting Cotton With Calcium
Arsenate for Boll Weevil Control
(Progress Report)
By
J. M. ROBINSON, Acting Entomologist
AGRICULTURAL EXPERIMENT STATION
of the
ALABAMA POLYTECHNIC INSTITUTE
M. J. FUNCHESS, Director
AUBURN
SUMMARY
The pre-square dust application just before the
cotton begins to square is advisable, providing there
are 20 or more weevils per acre.
The time to begin dusting cotton to protect the
young squares is when the infestation reaches 10 per
cent. Three dustings at intervals of four or five days
is sufficient to reduce the infestation.
The average increase in yield from dusting on the
Experiment Station at Auburn in 1924 was 204 pounds
of seed cotton per acre. Weather conditions were
favorable. The average increase in yield from dusting
on the same plot in 1925 was 37 pounds of seed cotton
per acre. The rainfall was below normal and the
temperature was above normal.
In 1924 the yield of seed cotton per acre on the
E. H. James farm was 85 pounds less on the dusted
plot than on the undusted plot. A drouth in July
caused the shedding of young bolls. There was an in-
crease of 260 pounds of seed cotton per acre on the
dusted plot in 1925.
The increase in yield on the dusted plot on the In-
ternational Harvester Company farm in 1924 was 170
pounds of seed cotton per acre. The weather caused
the shedding of bolls on these plots. The increase in
yield on the dusted plot on the Joe Phillips farm in
1925 was 420 pounds of seed cotton per acre.
S Thirty-six pounds of calcium arsenate will make
six applications per acre.
The average cost of dusting was $7.25 per acre.
Boll weevils can be controlled economically only
when the applications of dust are thorough and are
applied at the proper time.
whees-ene apl ie i e icaios f us a e oruh ndaeo
DUSTING COTTON WITH CALCIUM ARSENATE
FOR BOLL WEEVIL CONTROL
(PROGRESS REPORT)
By
J. M. ROBINSON, Acting Entomologist*
During the growing season of 1924 and 1925 cotton dusting
tests were made on three distinct types of soil, namely, Sandy
Loam, Cecil Clay, and Houston Clay. Calcium arsenate in dust
form and sweetened poison were used in 1924 for pre-square
treatments to control the over-wintered weevils. The test
plots were treated also with calcium arsenate and sweetened
poison to control weevils at squaring time. However, the sweet-
ened poison failed to keep the weevils under control so that it
became necessary later to use calcium arsenate in dust form on
the plots where sweetened poison was used.
The preliminary tests in 1924 with different methods and ma-
terials gave sufficient evidence to show the superior value of
calcium arsenate in dust form over the sweetened poison in
controlling boll weevils. Therefore, all tests were directed
to the control of boll weevil with calcium arsenate dust during
the 1925 growing season. The tests were made to learn when
to apply calcium arsenate and how often to make applications
of dust to control boll weevils economically under Alabama con-
ditions.
The data given in this circular is for the plots that were treat-
ed for boll weevil control With calcium arsenate in dust form.
The infestation records show a distinct reduction of weevil in-
festation following three applications of calcium arsenate in
dust form at intervals of four or five days. In all cases the in-
festation dropped below 20 per cent and in some cases it went
below 10 per cent.
This gave the conclusion that if the infestation is kept below
20 per cent while the middle and top crops are being set there
will be a reasonable assurance of ample 
protection against wee-
vil damage for the young squares and newly-set bolls. All of
this is true provided there is sufficient fertilizer under the cot-
ton to make a half bale or more per acre. It is advisable to
make the pre-square application of calcium arsenate dust just
before the cotton begins to square if there are 20 or more wee-
vils per acre.
* Field assistant, 1924, W. L. Owen; 1925, J. C. Gaines, Jr.
Infestation
Three to six stakes, five feet long, 
were used to mark the
stations in the field in keeping the infestation records. One
hundred squares were counted around each stake. The num-
ber of punctured squares gave the percentage of infestation.
When the infestation reached ten per cent three applications of
calcium arsenate were made at intervals of four to five days.
Four to six days after making the third application of calcium
arsenate another infestation count was made. If the infestation
approached twenty per cent other applications of dust were
made.
Cost
The average cost per acre of cotton dusted on the tests was
as follows: $2.00 for the dust gun, $4.20 for calcium arsenate,
and $1.05 for seven hours of labor to apply the dust, making a
total of $7.25 per acre. This was approximately the value of
100 pounds of seed cotton at the time of the tests.
The following pages contain a report of the experiments con-
ducted during 1924 and 1925.
THE EXPERIMENT STATION, AUBURN, 1924
In the spring of 1924 the departments of agronomy and ento-
mology began a series of cooperative boll weevil control tests
with calcium arsenate, using various rates of the Auburn method
of fertilizing.
Weather. -The rainfall for the growing season 
was above
normal except for the month of July which was 3 inches, or 2.6
inches below normal. A total of 3.04 inches of rain fell by Aug-
ust 6th, the total for the month being 4.95 inches. A twenty-day
period of clear weather, with daily maximum temperature rang-
ing from 88 to 99 degrees Fahrenheit, was approximately ideal
for squaring, blooming, and setting bolls.
Infestation. -The infestation of 
the dusted plots the 6th of
August was 4.7 per cent as shown by Table 2, page 6. On
August 12 the infestation was 10 per cent. The cotton was
dusted with calcium arsenate on August 12. Two 
other applica-
tions of dust were made at four-day intervals which resulted in
keeping the infestation at 10 per cent. The infestation on the
undusted plots August 25th had advanced to 61 per cent.
Picking Record. -The record 
indicated a definite control
from dusting with calcium arsenate at four day-intervals. 
The
proof was in the picking records, shown in Table 3, page 6.
The final picking records for the 1924 cotton crop showed that
where fertilizer was not used the yield 
was practically the same
on the dusted and undusted cotton. With 
500 pounds of ferti-
lizer per acre there was an increase of 222 pounds of seed
cotton on the dusted plot over the undusted plot. There was
a gain of 202 pounds of seed cotton on the dusted plot when
the rate of fertilizer was 1500 pounds per acre. This is shown
by figures 1 and 2, page 12. There was a gain of 98 pounds
of seed cotton from dusting when the rate of fertilizing was
2000 pounds per acre. All of these plots were dusted at four-
day intervals after the infestation reached 10 per cent until
three applications had been made.
THE EXPERIMENT STATION, AUBURN, 1925
Weather. -The rainfall for the growing season of May,
June, July, and August was 13 inches below normal. Cotton
squares were limited throughout the season. The average maxi-
mum temperature for these months was 4.2 degrees above
normal.
Infestation. -The infestation on the dusted plots was 
not
above 10 per cent except in the plots where the fertilizer was
applied at the rates of 1500 and 2000 pounds per acre. These
facts are shown in Table 3, page 6. On August 3 the general
infestation on the dusted plots was eight per cent. The fol-
lowing day an application of calcium arsenate dust was made,
and at four-day intervals thereafter until three applications
had been made. The infestation was lowered from eight to
two per cent. The infestation on the undusted plots advanced
from 19 to 40 per cent during the same 12-day period.
Picking Record. -The light rainfall and high temperature
controlled the weevils to such an extent that the difference
between the dusted and undusted plots was within the experi-
mental error, as shown by Table 3, page 6.
The rainfall record for the two years at Auburn as compared
with the normal rainfall is shown in Table I, which follows:
Table 1. Normal Rainfall Record Compared with 1924 and 1925
Month Normal 1924 1925
May -- - - 3.5 4.7 .71
June _ 4.2 6.6 .78
July --- -5.6 3.0 4.39
August |... 4.7 4.9 .01
September--- 3.1 4.7 5.10
This table shows that the rainfall during the growing sea-
son of 1924 was approximately normal. On the other hand, the
rainfall for the growing season of 1925 was below normal.
Table II, which follows, is a record of infestation and dates
of dusting cotton at Auburn:
6
Table 1.-Infestation and Dusting Records at Auburn 1924 and 1925
1924 1925
Average % Infestation Average % Infestation
DustingDusting
Dates Dates
Date Undusted Dusted Date Undusted Dusted
Aug. 6 0.0 4.7 { June 19 13.0 4.0 {
Aug. 12 12.2 10.2 Aug. 12 June 23 13.0) 1.5
Aug. 16 25.7 43.5 Aug. 16 June 30 2.5 1.4
Aug. 20 43.0 16.0 Aug. 21 July 4 3.2 0.4
Aug. 25 61.1 10.7 July 8 3.4 0.0
Aug. 28 74.0 58.5 July 11 5.2 0.0 {
Aug. 30 July 16 4.6 1.6
Sept. 3 July 23 8.2 4.8
July 28 4.5 3.8
Aug. 1. 7.3 2.2
Aug. 3 19.8 8.8 Aug. 4
Aug. 6 13.5 8.3 Aug. 7
Aug. 11 40.5 2.5 Aug. 11
Aug. 14 41.6 4.3
The amount of fertilizer applied per acre and the yields of
the dusted and undusted plots at Auburn in 1924 and in 1925
are shown in Table III, which follows:
Table II1.-Record of Fertilizer and Yields at Auburn-1924 and 1925
Pounds Seed Cotton per Acre
Rate of Fertilizer 
1924 
1925
Pounds per Acre Undusled Dusted Undusted Dusted
0 (Average of three plots 107 101 2851 251
500 -- - -- -- -- -- - 456 678 509 5335
1000--------------------___-----756 1050 695{ 770
1500--------------------- _ _- 1148 { 1352 813{ 837
2000 ____ __ _____ _ { 1304 1402 899 887
TEST WITH B. H. SMITH, AUBURN, 1924
In 1924 a test was conducted in cooperation with B. H. Smith,
a farmer living in Auburn.
The soil in this test had been built up by crop rotation.
Fertilizer was applied at the rate of 550 pounds per acre with
21 one-horse loads of stable manure added to each acre.
Infestation. -The infestation of the dusted plot reached 12
per cent on July 22, as shown by Table 4, page 7. An ap-
plication of calcium arsenate dust was applied the follow-
ing morning and at six-day intervals until three applications
had been made. The infestation records indicated a control
of boll weevils for that period. The squaring and blooming
records indicated that the maximum portion of the middle 
and
top crop was set during the same period.
Picking Record. -There was a gain of 
300 pounds of seed
cotton per acre on the dusted plot over the undusted. 
This is
shown in Table IV, which follows:
Table IV.- Infestation, Dusting, and Picking Records of B. H. Smith 
Test,
in Auburn, 1924
Average % Infestation
-~ Dusting Dates
Date Undusted 
Dusted
June 23-_----------9 
2
June 28------------ 
73
July 4----------- 
6 9
July 10 --- ___-___--4 5
July 14-----------.. 
6 6
July 19- ------------ 
- 713
July 22-------------- 
15 12 
July 23
July 28--------10 
16 July 29
Aug. 1--------------- 
17 5 
Aug. 4
Aug. 9 ----------- I 
23 10
Aug. 14--_----_____-I 
56 43 
Aug. 15
Aug. 20 ___ 
89 58 
Aug.20
Seed Cotton per Acre i 1620 
1 1920
TEST WITH. E. H. JAMES, 
LEE COUNTY, 1924
Mr. James lives in Lee 
County five miles west 
of Loacha-
poka. The plots used 
were heavy red soil. The 
previous crop
was weeds. The rate of 
home-mixed fertilizer was 
500 pounds
per acre.
Weather. -Favorable weather at planting 
time resulted in
a good stand of cotton. Weather 
during the early part of the
growing season was favorable 
for squaring. A few days 
of
dry weather in late July caused 
heavy shedding of squares and
small bolls.
Infestation. -The infestation on June 
19, 1924, was 8 per
cent on the undusted and 
12 per cent on the dusted plot, 
as
shown by Table V, page 8. 
The cotton was dusted first 
on
June 19 and at intervals of four 
or five days until three appli-
cations had been made.
Fourteen days later there was a two-per 
cent infestation in
the undusted plot and no infestation 
in the dusted plot,. The in-
festation on the dusted plots did 
not reach 20 per cent at
any future time. However, on July 
18 the dusted plots did
reach a 19-per cent infestation 
and a fourth application was
made.
Picking Record. -The picking records showed 85 pounds
more seed cotton per acre on the undusted 
than on the dusted
plot. This is shown by Table 
5, page 8.
TEST ON E. H. JAMES' FARM, 1925
Growing Season 1925
The plots on the Cecil Clay loam during the season of 1925
were located on the same farm with very similar soil conditions.
The rate of home-mixed fertilizer was 300 pounds plus 9 loads
of stable manure per acre.
There was only a fair stand of cotton due to a lack of mois-
ture at the time of germination.
Infestation. -On June 27 the infestation on the dusted plot
was 14 per cent, which is recorded 
in Table 5, page 8. Dust
was applied at intervals of five 
and seven days, beginning July
1. By July 20 the infestation on the dusted 
plot had dropped
to 6 per cent, as contrasted with a 
17-per cent infestation on the
undusted plot. A second group of 
dustings became necessary
by July 20 when the infestation in 
the dusted plot advanced to
17 per cent. The dustings kept the infestation 
below 20 per cent
until August 26.
The undusted plot advanced in infestation 
from 17 per cent
on July 20, to 74 per cent on August 11. With squaring 
almost
stopped, the weevils began making egg 
punctures in the young
bolls. A sixth dusting was made August 
the 6th to protect the
young bolls from weevil damage. The 
infestation records in-
dicated a control of boll weevils from dusting.
Picking Record. -The picking records of the dusted plot
showed an increase of 260 pounds of 
seed cotton over the un-
dusted plot, which Table 5, page 8, 
shows.
A record of the test in cooperation with E. H. James, a farmer
living near Auburn, follows:
Table V.-Infestation, Dusting, and Picking Records 
of E. H. James Test,
near Auburn, 1924
1924 1925
Average % Infestation Average % Infestation
Dusting 
Dusting
Dates Dates
Date Undusted Dusted Date Undusted 
Dusted
June 19 _- 8 12 June 19 June 27... 23 
12 July 1
June 23 __ 14 12 June 24 July 3 
21 16 July 6
June 27 _ 10 3 June 28 July 8 -- 
27 9 July 13
July 3__ 2 0 July 19 fuly 20 17 
6 July 21
July 11__ 9 2 fuly 24 
24 17 July 27
July 18 __ 23 19 July 29 -
28 13 Aug. 6
July 24 __ 21 4 Aug. 5 
61 19
July 31__ 11 2 Aug. 11 
74 18
- _ Aug. 18 58 20
Seed I Seed
Cotton Cotton
Per Acre 755 670 Per Acre
480 7401
480 740
9
TEST ON INTERNATIONAL HARVESTER COMPANY FARM
This farm is located in the Black Belt near Montgomery.
Tests for boll weevil control with calcium arsenate dust were
made on it in 1924 and in 1925.
The 1924 test plots were on Houston Clay soil that had not
been cultivated in twenty years. Home-mixed fertilizer 
was ap-
plied at the rate of 510 pounds per acre.
The infestation (recorded in Table 6, page 10) reached 16 per
cent July 21. Beginning July 22, three applications of calcium
arsenate were made at four-day intervals. The infestation
dropped from 16 to 7 per cent on the dusted plot, while the
infestation on the undusted plots advanced to 20 per cent dur-
ing the same period.
In every case where the applications of calcium arsenate in
dust form were applied at intervals of four or five days the in-
festation was reduced to less than 10 per cent. A second series
of three dustings was made to protect young bolls.
Picking Record.-The picking records disclosed a difference
of 170 pounds in favor of the dusted plots. Table 6, page 10,
is a record of this.
TEST ON JOE PHILLIPS' FARM
A test was made with Joe Phillips on Houston Clay soil in
Montgomery County in 1925. These plots had been cultivated
annually for many years.
Favorable weather resulted in a good stand and a good crop.
Fertilizer was applied at the rate of 400 pounds of 8-4-4 per acre.
Infestation. -The infestation on June 17 (recorded in Table
VI, page 10) was 31 per cent on the undusted plots and 27 per
cent on the dusted plots.
The first application of poison was made on this date and
at four-day intervals thereafter until three applications had
been made. The infestation on the dusted plot dropped from
27 per cent to two per cent. On the undusted plot the infestation
during the same period dropped from 21 per cent to 13 per cent.
Three extra dustings, beginning July 13, were applied at in-
tervals of four or five days, keeping the infestation below 20
per cent. The infestation on the undusted plot remained above
20 per cent during the same period. On August 4 an applica-
tion of calcium arsenate was made to protect the young bolls.
Control of weevils was conspicuous in these tests. The in-
festation records indicated a decided control.
Picking Record. -The yield of 670 pounds of seed 
cotton
per acre on the undusted plot and 1090 pounds on the dusted
plot (Fig. 3, page 11), was conclusive evidence that boll weevils
Were controlled profitably even under Black Belt conditions.
It took approximately 100 pounds of seed cotton to cover the
10
expense of dusting so that this test showed a net gain of 320
pounds of seed cotton per acre for dusting.
In 1924 a test was made on the farm of the International
Harvester Company, near Montgomery. In 1925 the test was
on Joe Phillips' farm, near Montgomery, on the same type of
soil. Table VI, which follows, is a record of these tests.
Table VI.--Infestation, Dusting, and Picking Record of Tests, near Mont-
gomery, in 1924 and in 1925
1924 1925-
Average % Infestation Average % Infestation
Dates Dates
Date Undusted Dusted Date Undusted Dusted
July 1 6 2 June 17 21 27 June 17
July 8 3 2 June 20 __ 16 18 June20
July 15 3 - 6 June 24 12 11 June 24
July 21 16 16 July 22 June 29 13 2
July 25 __ 25 10 July 26 July 6 17 7
July 29 20 7 July 30 July 13 23 20 July 13
Aug. 5 __ 21 7 Aug. 12 July 18 20 17 July 18
Aug. 12 __ 70 31 Aug. 19 July 22 23 15 July 22
Aug. 18 __ 68 40 Aug. 30 July 27 29 8
Aug. 25 67 8 Aug. 3 53 14 Aug. 4
Seed J1Seed
Cotton I Cotton I
Per Acre 235 405 . Per Acre 670 1090
Timeliness and Thoroughness
Cotton dusting should be done properly or it should not be
done at all. Where poison is to be used to control boll wee-
vils it is necessary to have enough dust for a season and the
dusting machinery on hand before time to begin dusting. It is
also essential that the per cent of infestation be determined at
frequent intervals after squaring begins.
The infestation can be determined by counting all the squares
on the plants, keeping a count of the punctured squares, until
one hundred squares have been counted. The number of punc-
tured squares will give the per cent of infestation. For example:
if the number of punctured squares, at the first station, is eleven
out of 100 squares counted, the infestation is 11 per cent.
When the average infestation of all the stations is 10 per cent
it is time to begin dusting. When many squares have fallen
to the ground the infestation is much higher than 10 per cent.
Unfortunately, many farmers have used fallen squares as a
guide to indicate the percentage of infestation, which means that
poison was applied too late for best results.
The dust should 
lbe ap~pliedl with 
a (lust gun. 
This miay be 
a
hand gun, 
a two-row machine, 
a three-row 
machine, or 
an air-
phi ne. Calcium 
arsenate will 
distribute oxver 
the cotton 
better
wh~en the 
air is still 
or nearly 
so. Therefore, 
early mnornin 
g,
late evening, 
or nih are 
preferred for 
dulstinig.
If the fol iage 
is moist, calcium 
arseniate wvill 
stick to the plants
better. hlowever, 
(t(efinite control 
has been obtained 
by dusting
cotton when 
the plants were 
dry and the 
air quiet.
If the infestation 
does not reach 
1(0 per cent 
there is little 
or
In) profit to lie 
ob tined from 
dlusing. Making 
applications 
of
cal ciunm arsena 
te promptly 
and thoroughly 
when they are 
needed
wv ilSassure a 
morce economic 
control of boll 
wveevils.
Dusted ndus ted
Dusted
D~ust'd--1050 Pond~(s Seed Cotton
U ndusted-756 Pouinds .Seed 
Cottn