Further results from airplane dusting in Arizona for hemipterous cotton insect control, crop season of 1940


Material Information

Further results from airplane dusting in Arizona for hemipterous cotton insect control, crop season of 1940
Physical Description:
Cassidy, T. P
Barber, T. C
United States -- Bureau of Entomology and Plant Quarantine
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine ( Washington, D.C )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030285040
oclc - 779478594
System ID:

Full Text

E-1543 USo.June 1941


By T. P. Cassidy and T. C. Barber, Division of
Cotton Insect Investigationsl/


Investigations on control of hemipterous cotton insects in
Arizona by the use of insecticides applied with airplanes were con-
tinued during the crop season of 1940 for fcrth.er testing of control
methods on a practical commercial basis. In 1938 and 1940 circulars2/
were issued by the Bureau of Tntomology and Plant Z-arantine listing
the species of hemipterous insects responsible for reducing cotton
yields and lowering grades of Arizona cotton. These circulars
described the nature of damage to cotton, the extent of damage in the
State, and the losses caused by hemipterous insects directly and indi-
rectly, and gave the progress of experimental work done on this group
of insects through 1939. The results of the experiments of 1940 are
given at the present time because of the great interest in the work
and the demand for information by the growers for the coming season.

Field experiments conducted during 1933 to 1938 with several
insecticides applied with hand and power-operated dusting machinery
indicated that profitable gains in yield could be minde by the use of
insecticides and the quality of cotton improved. However, these methods
of application were not entirely satisfactory for large-scale co mercial
dusting under Arizona conditions owing to irrigation schedules, the
rank growth of cotton plants, sudden insect migrations to cotton fields
requiring immediate poison applications, etc. The use of airplanes
appeared to be the most satisfactory method for quickly dusting large
acreages following insect migration into the fields without damaging
rank growing cotton.

1/ The writers were assisted in the field by W. A. Stevenson,
L. W. Sheets, J. M. Breazeale, and H. J. Crawford.
2/ Cassidy, T. P., and Barber, T. C. Hempterous Cotton Insects
of Arizona and Their Economic Importance and Control. U. S. Dept. Agr.,
Bur. Ent. and Plant Quar. Circ. E-439 (mimeographed).
Cassidy, T. P., and Barber, T. C. Investigations in Control
of Hemipterous Cotton Insects in Arizona by the Use of Insecticides.
U. S. Dept. Agr., Bur. Ent. and Plant Quar. Circ. -506 (mimeographed).


In 1939 a series of large-scale dusting experiments was conducted.
cooperatively with the J. G. Boswell Company and a number of cotton
growers to obtain information on the efficiency, practicability, and
cost involved in this method of insect control, and to determine the
minimum number of injurious hemipterous cotton insects that would justify
the expense of airplane dusting. In 1940 a similar series of airplane
dusting experiments was conducted in cooperation with the J. G. Boswell
Company, the Cortaro Farms Company, and a number of cotton growers.
The same insecticide (paris green 7 1/2 percent, dusting sulfur 92 1/2
percent) was used both years, the same dosage of 15 pounds of insecticide
per acre per application was used, and the same time interval of 7 days
between dustings was followed as closely as possible. The main difference
between the experiments of 1939 and 1940 was in the number of insecticide
applications made per field. In 1939 a rigid schedule of applications
was followed after dusting had commenced and each field in the Salt
River Valley received seven applications of insecticide irrespective of
whether the insect population was light or heavy. This gave valuable
information as to the minimum number of injurious hemipterous insects
required to justify the expense of control. However, several of the
experiments of 1939 failed to show profitable results because of the
excessive number of applications.

Cotton-Dusting Experiments by Airplane in 1940

In the experiments of 1940, 4 representative fields of short-
staple Acala cotton and 3 fields of long-staple SxP cotton in the Salt
River Valley and one field of long-staple cotton in the Santa Cruz Valley
were dusted. Each field contained 40 or 80 acres and was laid out in
alternate dusted and check plots of 10 or 20 acres so that half of each
field was dusted and the other half left undusted for comparative purposes.
The number of applications used depended upon the abundance of the insects.
Population counts were commenced June 17 by using the sweep-net method
of collecting. When fields were found to have an average population of
12 or more mirids (L etc.) or other injurious hemipterous insects
per 100 net strokes, or 6 or more stinkbugs were found by examining 100
plants, it was assumed that sufficient insects were present to justify
the expense of airplane dusting for their control, and dusting was begun.
However, when populations in the dusted areas of the fields dropped below
this number the dusting was stopped until the insects again reached the
above populations. By following this procedure the number of dustings
made in the different experimental fields varied from two to seven.

The insecticide used was a commercial mixture of 7 1/2 percent
paris green and 92 1/2 percent dusting sulfur applied at the rate of 15
pounds per acre at 7-day intervals. The first application was made on
July 10 and the last on August 22. Dusting conditions during 1940 were
almost perfect for airplane dusting and practically every application
was made under excellent weather conditions. In 1939 conditions were very
different, and it was necessary to change the dusting schedule on several
occasions because of high winds and unfavorable weather. The favorable
conditions prevailing during 1940 are considered an important factor in
the successful results that were obtained in the experiments.

After the cotton from the dusted and check areas was picked and
weighed it was put into separate trailers and followed through the
gins so that the percentage of lint, the grade, and the staple length
of all cotton produced could be determined. By comparison of these
records the value of the cotton from the dusted and nondusted areas
of each experimental field was determined and the profits from the
dusting were calculated.

Results of the 1940 Experiments

Rendition of lint (gin turn-out), grades, and staple .--Gin records
from three fields of short-staple and three fields of long-staple cotton
located in the Salt River Valley show that the dusted cotton yielded 0.14
percent more lint than did the undusted. The classinig and grading records
of the lint from all the experimental fields are shown in table 1.

Table 1.- Classing and grading records of cotton from experimental
fields, 1940

Dusted Check
No. of bales Percent No. of bales Percent
Short staple--Acala
Total yield 86 -- 65 --
Strict Middling 27 31.4 17 26.2
Middling 49 57.0 42 64.6
Strict Low Middling 10 11.6 6 9.2
White 81 94.2 52 80.0
Spotted 5 5.8 13 20.0
7/8" 0 0.0 3 4.6
15/16" 13 15.1 13 20.0
11 46 53.5 34 52.3
1-1/32" 27 31.4 15 23.1

Long-staple-- SxP
Total yield 39 -- 33 --
No. 1 4 10.3 0 0.0
No. 2 16 41.0 15 45.5
No. 3 18 46.2 14 42.4
No. 4 1 2.6 4 12.1
1-1/2" 38 97.4 30 90.9
1-7/16" 1 2.6 3 9.1

Owing to excessive rainfall during the picking season, cotton grades
were adversely affected generally throughout the State. Nevertheless, the
above records show that the dusted cotton averaged somewhat better in
grade and staple than the undusted cotton from the check plots.

Lii~i{ -.. -rA~of


Increased Value of Cotton from Dusting

As shown in the classing and grading records, a better quality
of cotton was produced in the dusted than in the nondusted areas. In
order to determine the value of the better quality of cotton in dollars
and cents, each bale of short-staple cotton from the dusted and check
areas was valued according to the Government loan value, f.o.b. ware-
house, Phoenix, Ariz., for the different grades and staples. The long-
staple cotton was valued according to average commercial prices paid for
different grades in Arizona. The increased value of the cotton from
three fields of short-staple and three fields of long-staple located in
the Salt River Valley, computed on a 500-pound bale basis, varied con-
siderably in the different locations, depending upon the intensity of
insect populations. The increased value of the short-staple varied from
20 cents to $1.66 per bale and that of the long-staple varied from $2.85
to $30.05 per bale for the different fields.

Yield and Cost Data

In determining the profit or loss from comparable areas of the
experimental fields all the costs for insecticides and dusting by air-
planes as well as those for picking, weighing, nauling, ginning, bagging,
and ties for the increase in yields in the dusted fields were charged at
the prevailing rates. In computing the costs per acre the exact acre-
ages of the dusted and check areas were determined. All irrigation
ditches, roads, fence rows, and. otheridle areas were eliminated from the
acreage. The measured net acreage of an 80-acre block of short-staple
cotton, which was divided into two fields (4A and 4B) by an irrigation
ditch and a road and surrounded on four sides by a fence, was 72.8 acres,
of which 37 were dusted and 35.8 acres were left undusted for checks.

The detailed records of the cost of dusting and the value of the
crop produced in the dusted and check areas of these fields are shown
in table 2, as an example of how the costs and profits were calculated.

Table 2.-- Yields and cost data of dusting experiment

Field 4A and 4B

Total seed cotton produced, dusted areas 73,550 lbs.
Total seed cotton produced, check areas 49,160 lbs.
Difference gained 24,390 lbs.
Difference gained 49.61 percent

Total lint cotton produced, dusted areas 26,299 lbs.
Total lint cotton produced, check areas 17,333 lbs.
Difference gained 8,966 lbs.
Difference gained 51.71 percent

Average price per pound, dusted cotton 9.33 cents
Average price per pound, check cotton 9.00 cents
Difference due to grade, color, and staple .33 on


Table 2. (cont.)

Dusted 26,299 lbs. lint at $9.33 $2,453.30
Check 17,333 lbs. lint at $9.00 1,559.57
Difference gained 893.73
Difference gained 57.31 percent

Total seed produced in dusted cotton 45,004 lbs.
Total seed produced in check cotton 30,351 lbs.
Difference gained 14,653 lbs.
Difference gained 48.28 percent

Dusted seed sold for $ 430.05
Check seed sold for 289.32
Difference gained 140.73
Difference gained 48.64 percent

Gross profit from lint cotton $ 893.73
Gross profit from seed 140.73
Gross profit 1,034.46

Cost records of cotton gained:
Dusting at $1.14 per acre per application (7 applications) $319.20
Picking 24,390 lbs.seed cotton gained at 750 per 100 lbs. 182.92
Weighing and hauling 24,390 lbs. seed cotton at 10 per 100 24.39
Ginning 24,390 lbs. seed cotton gained at 304 per 100 73.17
Bagging and ties for 8,966 lbs. lint cotton gained at
$1.25 per 500-lb. bale 22.41
Total cost 622.09

Gross profit $1,034.46
Total cost 622.09
Net profit 412.37
Net profit per acre 11.15

The yields, costs, and profits from the three fields of short-
staple and the three fields of long-staple cotton grown in the Salt River
Valley and from one field of long-staple in the Santa Cruz Valley that
were dusted for hemipterous insect control have been computed on a per-
acre basis and summarized in table 3.

It will be seen from this table that the number of dust appli-
cations ranged from four to seven, or an average of six in the short-
staple fields. Five applications were made in all the long-staple fields
in the Salt River Valley, and only two applications in the field in the
Santa Cruz Valley. The pounds of seed cotton gained per acre as a re-
sult of the dusting in the short-staple fields varied from 267 to 817
pounds, or an average of 569 pounds per acre. For the four long-staple
fields there were variations in gains of 201 to 317 pounds, or an aver-
age of 268 pounds per acre. After all expenses involved and the value
of the cotton gained were determined it was found that the short-staple


fields gave a net profit varying from $3.73 to $14.30, or an average
of $9.00 per acre. The profits for the long-staple fields varied
from $6.78 to $13.24, or an average of $9.41 per acre for the four
fields. All fields combined gave an average net profit of $9.23
Der acre.

Table 3.-- Yields, costs, and profits per acre of airplane dusting
experiments for hemipterous insect control in Arizona
in 1940


Yield in pounds
of seed cotton
Dusted Check

1 S.R.V. 1,258

4(B) S.R.V.2,070

Average 1,823

2 S.R.V.

5 S.R.V.

6 S.R.V.

















Pounds Percent


















Number Cost Additional cost of cotton gained
of dust of Picking, Ginning,
applica- Dust-weighing, bagging, Total
tions ing hauling and ties

Short-staple Acala cotton

4 $4.56 $2.27 $1.06 $7.89

7 7.98 6.95 3-1 18.11

7 7.98 5.26 2.41 15.67

6 6.84 4.83 2.22 13.89

Long-staple SxP cotton

5 5.70 5.08 2.11 12.89

5 5.70 4.16 1.72 11.5g

5 5.70 4.74 1.96 12.40

2 1.94 3.22 1.34 6.5o

4.3 4.76 4.30 1.7 10.84

Value of cot- Net
ton gained pr
Lint Seed Total acre








L9. 24


























31262 09230 4053

An 80-acre field of short-staple cotton grown in the Salt River
Valley near 1lesa during 1940 was dusted four times during the season
for hemipterous insect control but was not included in the above summary.
The season's records on insect populations, boll injury, form counts,
etc. indicated that a profit from the dusting operations would be made
in this field. However, owing to adverse weather conditions during the
picking season and a shortage of labor, the cotton was not picked.
It was allowed to stand in the field until January 1941, when it was
finally snapped. While the dusted portion of the field produced 306
pounds or 20.6 percent more snapped cotton per acre than did the
undusted, the field showed a loss from the dusting. The lint cotton
from the field sold for 6.5 cents per pound irrespective of grade and
color, and after all expenses for dusting, picking, weighing, hauling,
bagging, ties, and ginning were deducted the increased yield made from
the dusting showed a net loss of 17 cents per acre. This experiment
indicates that no profit can be made from dusting cotton if it is
not picked and handled in a normal way.

Summary and Recommendations

The series of airplane-dusting experiments conducted during the
season of 1940 show that a reasonable profit can be made from dusting
long- and short-staple varieties of cotton with a mixture of 7 1/2
percent paris green and 92 1/2 percent dusting sulfur for the control
of hemipterous insects.

The dust should be applied at the rate of 15 pounds per acre
at 7-day intervals when 12 or more mirids (Lu, etc.) or other in-
Jurious hemipterous insects can be collected per 100 sweep-not strokes,
or when 6 or more stinkbugs can be found by examining 100 plants.
When the insect populations drop below these numbers the poison appli-
cations should be discontinued until populations again reach 12 or
more per 100 sweep-net strokes or 6 or more stinkbugs per 100 plants.
Applications should be made during the early morning when conditions
are most favorable for thorough coverage.