Experiments with DDT for the control of the European corn borer infesting sweet corn at Toledo, Ohio, in 1944

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Material Information

Title:
Experiments with DDT for the control of the European corn borer infesting sweet corn at Toledo, Ohio, in 1944
Physical Description:
11 p. : ; 27 cm.
Language:
English
Creator:
Batchelder, C. H
Questel, D. D ( David Dewitt ), 1899-
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:
European corn borer -- Control -- Ohio -- Toledo   ( lcsh )
Sweet corn -- Diseases and pests -- Control -- Ohio -- Toledo   ( lcsh )
DDT (Insecticide)   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
by C.H. Batchelder and D.D. Questel.
General Note:
Caption title.
General Note:
"E-659."
General Note:
"May 1945."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030289698
oclc - 779849470
System ID:
AA00025117:00001

Full Text
L1E'^'AKI
STATE PLANT BOARD
May 1945

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

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XPIRIMNTS WITH DDT FOR THE CONTROL OF THE EUROPEAN
CORN BOROR INFESTING SEIT CORN AT TOLIDO, OHIO, IN 1944

By C. H. Batchelder and D. D. (estel1/
Division of Cereal and Forage Insect Investigations


The experiments described in this report were conducted in
sweet corn grown near Toledo, Ohio, during 1944 for the purpose of
determining dosage requirements and effectiveness of DDT as an in-
secticide for control of the first generation (June-July)of the
lropean corn borer (Pyransta nubilalis (Hbn.)). The DDT sprays
and dusts were applied with a wheelbarrow sprayer, a self-propelled
ground duster, and air-borne dispensing equipment designed for
applying dusts and concentrated sprays. Although considered pre-
liminary in nature, the experiments have produced information
important to further use of this insecticide in field-plot tests
and in commercial applications.

DDT Sprays Applied with Ground Machine (D. D. (iestel)

The following water suspensions of DDT were tested as sprays in
comparison with a spray containing rotenone: DWT (technical,
undiluted), 10.8 percent of DDT in pyrophyllite, and 5 percent of
DDT in an unknown diluent (Gesarol Spray Insecticide). Sodium
monosulfomate of butylphenylphenol (Areskap) was added to all sprays.

The experimental plots were four rows wide and 25 feet long in
randomized blocks. All treatments were replicated four times and
each treatment consisted of three applications. For each application
approximately 175 gallons of spray per acre were applied with a
wheelbarrow sprayer operated by a gasoline engine and applied with
a hand-directed nozzle that produced a solid cone of spray. At the
time of the first application (June 17) the corn was 36 inches high
with 70 percent of the tassels merging. Additional applications
were made on June 22 and 27. Dates and amounts of rainfall for the
spraying season were as follows: June 19, 0.21 inch; June 22, 0.10
inch; and June 23, 2.13 inches. The results of these tests are given
in table 1.



I/ The self-propelled ground equipment utilized in these experi-
ments was designed and built by F. Irons and staff of the Bureau of
Plant Industry, Soils, and Agricultural Engineering. Mr. Irons and
his staff also rendered valuable aid in the application of insecticide
materials.



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Owing to the unusually short period during which oviposi-
tion took place in these plots, only 3 applications were made; yet
excellent control was obtained with these materials, without any
apparent injury or other effect on the corn. The spray in which 10.8
percent of DDT in pyrophyllite was used as the source of the DDT
was outstanding in control of the borer and reduced the population
in the plants from 1834 to 38 and in the ears from 496 to 4. The mixture
readily went into a water suspension, whereas much difficulty was
encountered in attempting to put undiluted DDT into suspension.

DDT Dusts Applied with Ground Machine (0. H. Batchelder)

An experiment was conducted to establish the dosage required
for application of DDT dust with ground equipment to infested corn.
Data of this kind were also considered necessary in connection with
the use of DDT in subsequent tests of new types of ground and aerial
equipment. For these reasons special attention was given the mechani-
cal adjustment of the duster equipment.

Precise control in the mechanical operation of the power-
operated and self-propelled duster used in this experiment assured
uniform dosage by regulation of travel speed, feed rate, ratio of
dust to air volume, and physical condition of each hopper load.
Dusts containing 0.75, 1.5, 3, and 6 percent of DDT were made from
a 10.8 percent DDT-pyrophyllite mixture by the addition of more
pyrophyllite. These dusts were applied at the rate of 40 pounds per
acre-application to obtain dosages of 0.3, 0.6, 1.2, and 2.4 pounds
of DDT per acre. No accessory agents were included in the mixtures.

This experiment was conducted in a'commercial planting of
extra-early hybrid sweet corn, Spancross, and the plots were arranged
in randomized blocks. All treatments were replicated 4 times, and
each treatment consisted of 4 applications. An infestation of 10
larvae per plant (primary stalk and ears) prevailing at the time of
harvest caused severe loss in untreated plots.

Applications were made on June 18, 25, and 30, end July 5.
They would have been started 5 days earlier but for mechanical diffi-
culties encountered in assembling the duster equipment. The first
application was made when the plants were in late whorl and early green
tassel, the second during late tassel, and the last two during silking
growth stages.







As shown in table 2, borer reduction increased with each in-.
crease in dosage without indication of leveling off within the dosage
range. Although a dosage of 1.2 pounds of DDT did not provide a
sufficiently high degree of control in these experiments, borer
mortality might have been considerably greater and 2.4 pounds might
have been more than necessary had there been no delay in the applica-
tion schedule.


Table 2.-Borer reduction in extra-early hybrid sweet corn, Spancross,
treated in dosage-mortality test of DDT applied in dust form
with ground equipment (4 replications, 40 pounds of mixed
dust per acre-application)

Dosage of Borers per 100 Reduction in
Concen- DDT plants surviving borers
ration per acre- at time of harvest ____
of DDT application in In In In
_________ _________ -lant ears lantear
Percent Pounds Number Number Percent Percent


6 2.4 91 19 91.0 95.1
3 1.2 277 90 72.5 76.9
1.5 .6 359 156 64.3 60.0
.75 .3546 197 45.8 49.5

Check (untreated) 1007 390 -



P/ Primary stalk and its appendages but not including tillers.


Bars of salable size were graded in three classes: (1) Ho. 1 and
borer-free, (2) salable-infested, having borers in silks or shank but
no injuries of kernels or husks, and (3) culled due to borers or to
borer injuries of kernels and husk. The yields are summarized in
table 3 according to treatment. Borer reduction is reflected in the
yields obtained in plots treated at the several dosage levels.
Particularly noteworthy are the higher yields in numbers of ears of
salable size in treated plots as compared with untreated plots. All
dosages more than doubled the number of salable as well as No. 1 and
borer-free ears, and the quality of the yield improved continuously
with dosage increase. No injury or other effect on the growth of
the corn was observed.





-5-


Table 3.-Yield increase in extra-early hybrid sweet corn, Spancoross,
treated in dosage-mortality test of DDT applied in duet form
with ground equipment. (4 replications, 40 pounds of mixed
dust per acre-application)

Distribution
Dosage Increase of ears of
of DDT Ears per 100 plants in ears salable size
per Sal- No. 1 No. I No. 1
Concen- acre- Culls able- and Total and Culls and Total
tration appli- due to in- borer- sal- borer- due to borer- sal-
of DDT cation borers tested free able free borers free able

Percent Pounds Number Number Number Per- Per- Per- Per- Per-
cent cent cent cent cent
6 2.4 1$ 7 126 280 530 10.1 85.1 89.9
3 1.2 22 106 266 430 20.5 65.8 79.5
1.5 .6 26 71 177 255 1.2 50.3 68.8
.75 .3 66 26 46 106 130 47.8 33.2 52.2
Check (untreated) 96 15 20 73.3 15.3 26.7

DDT in Dusts and in a Concentrated Spray Applied by Airplane
(C. H. Batchelder)

Preparations of DDT were dispensed with airplane equipment to deter-
mine their suitability and effectiveness when so applied for corn borer
control in plantings of sweet corn subject to heavy infestation and damage.
The materials used in these tests were a MDT dust, a cube-pyrophyllite dust,
and a concentrated spray containing DDT in an oil vehicle. The dusts were
applied at a rate of about 40 pounds and the spray at about 2.25 gallons
per acre-application. There was great variability, however, in the amount
of material deposited from the center of the swath laterally in each direc-
tion as well as along the line of flight taken by the plane.

The concentrated spray was assembled in the following proportions

Pounds per gallon
DDT, technical (GNB-A-DDT) .... ............... 0.67
Solvent, petroleum distillate (Sunoco 7-T) ......... 1.34
White-oil vehicle, Superla grade (125 seconds
Saybolt) ........................................ 5.36
Emulsifying agent (Triton X-100, an aralkyl
polyether alcohol) .......................... .. .16


Total


7.53





-6-


The petroleum distillate was a low-priced commercial prepara-
tion containing olefinic and aromatic hydrocarbons. This material
compared very well with other common solvents in its ability to
dissolve DDT and with reference to plant tolerance. The
white oil has been used for earworm control and was selected because of
its safety and availability. It is believed that grades of white oil
with lower viscosity would be Just as satisfactory. The emulsifying
agent was included to increase the mobility of residues in the presence
of surface moisture; it may not have been necessary.

The insecticides were applied with a Piper Cub plane carrying
interchangeable dusting and spraying equipment. Owing to unevenr, delivery
and also to reduction in deposit laterally from the central rows of the
treatment swath by both types of equipment, it was not possible to
compute exact delivery rates. Rates of 1.5 pounds of DDT and of 0.5
pound of rotenone per acre-application are therefore considered approxi-
mate averages for the five central rows of the treatment swath. It is
probable that improvements in airplane equipment now in progress will
eventually result in more even and better controlled dosages of dusts
and sprays.

Tests in single-strip plots were made in a field providing
three flight strips with ample buffer and check areas. The field had
been planted with three varieties of sweet corn-Earligold, Whipcross,
and Evergreen. These varieties differed in growth rate as well as in
rate of infestation and characteristic yields.

Treatments were applied on June 21, 24, and 29, and July 4.
It is of interest to note that,although it was impossible to keep to
schedule with the ground duster on account of a muddy field following
rain on June 23, the condition of the field was no hindrance to plane
operation.

Reduction of population in the plants and in the ears for a
five-row swath, and maximum reduction as obtained in the center row of
the swath, on which the average dosage was heavier than it was on the
lateral rows, have been summarized in table 4, The data show that
considerable variation in control occurred according to the variety.
In Evergreen DDT in an oil vehicle gave 92 percent reduction of borers
in ears in the swath, and 100 percent in the center row of the swath,
but in Vhipcross it gave only 65 percent reduction in the swath and
85 percent in the center row of the swath. This was apparently due
to differences in the growth stage of these varieties at the time of
treatment and accompanying differences in the development of the
infestation. Comparison of borer reductions on Evergreen following
applications of DDT in dust and in solution showed the concentrated
spray to be superior. It is also noteworthy that an average borer
reduction of 89 percent prevailed in the ears of Earligold treated
with cube dust. The potentiality of DDT as a corn borer insecticide
was shown by the 100 percent protection provided the ears of Zvergreen
in a central row of the plot treated with the solution of this in-
secticide in oil.







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The yields of 99 and 100 percent for No. 1 and borer-free
ears obtained with DDT in oil, shown in table 5, indicate higher
protection in Mvergreen than has been obtained with other insecti-
cides. Ears of salable size were graded in three classes as
described in the preceding experiments with ground-duster equipment.
Dust preparations of DDT and cube provided similar proportions of
total salable and No. 1 and borer-free er-xs,although these treat-
ments were applied to different varieties. As might be expected
from the lower borer-reduction shown in table 4, the yields of
salable and borer-free ears in Whipcross treated with DDT in oil
were also lower than those obtained in the later Evergreen variety.
The percentage of salable-size ears culled because of borer in-
festations was much less in all treated than in untreated plots,
and no injury or other effect on the growth of the corn was observed.














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Summary

In 1944 three applications with groun-sprayer equipment near
Toledo, Ohio, at 5-day intervals to early-market sweet corn gave
excellent borer control with three DDT preparations. Of three materi-
als tested, 10. percent of 'DDT in pyrophyllite was outstanding from
the standpoint of reducing borer populations in the plant as well as
of the ease with which it could be put into a spray suspension. This
material gave 97.9 percent reduction of borers in the plant and 99.2
percent reduction in the ears, when applied with a wheelbarrow sprayer
run by a gasoline engine and applied with a hand nozzle that produced
a solid cone of spray.

Your applications of dusts containing 0.75, 1.5, 3, and 6 per-
cent of DDT in pyrophyllite were made 5 to 7 days apart with a ground
machine to sweet corn in dosages of 0.3, 0.6, 1.2, and 2.14 pounds per
acre-application. Borer reduction increased with each increase in the
dosage rate, and at the highest rate provided 95 percent reduction of
corn borer larvae infesting the ears, even though the applications were
begun too late for best results against newly hatched larvae. The
yield resulting from treatments applied at a rate of 2.4 pounds of DDT
per acre-application was graded 59.9 percent salable and 85.1 percent
No. 1 and borer-free.

On the variety Rvergreen four airplane applications 3 to 5 days.
apart of a concentrated spray containing 8.9 percent of DDT in white
oil, at the rate of about 2.25 gallons per acre, provided borer reduc-
tions in plants of 98 percent with all ears salable size and borer-free
in center rows of the treated swath. DDT in dust form applied by air-
plane to the same variety was somewhat less effective than the concen-
trated spray. Aerial dust treatments resulted in 52.3 percent reduction
of borers in the ears, and a yield 55.6 percent of which was No. I and
borer-free.

All treatments resulted in an increase in the number of ears of
salable size as compared with the yield of untreated check plots.


.-'' s -.




UNIVERS TY OF FLORIDA
11111 III, III1 I',HI',I~~~
3 1262 09238 7041


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