Field tests with insecticides to control the European corn borer in early market sweet corn at Toledo, Ohio, in 1943

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Title:
Field tests with insecticides to control the European corn borer in early market sweet corn at Toledo, Ohio, in 1943
Physical Description:
16 p. : ill. ; 26 cm.
Language:
English
Creator:
Questel, D. D ( David Dewitt ), 1899-
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Dept. of Agriculture, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
European corn borer -- Control -- Ohio   ( lcsh )
Sweet corn -- Diseases and pests -- Ohio   ( lcsh )
Insecticides -- Testing   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
by D.D. Questel.
General Note:
Caption title.
General Note:
Typescript.
General Note:
"January 1944 ; E-609."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030289069
oclc - 779843880
System ID:
AA00025106:00001

Full Text
STATE PLANT BOARD


January 1944

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

F130 TESTS WITH INSECTICIDES TO CONTROL TM EUROPEAN CORN
BORER IN EARLT MARKET SWEET CORN AT TOLEDO, OHIO, IN 1943

By D. D. Queetel, Division of Cereal and Forage Insect Investigations

Introduction

Three fields of early market sweet corn were used in conducting
insecticide tests in 1943 against the first generation of the European
corn borer (Pyrausta nubilalis (Ebn.)). The work was divided into
(1) tests of experimental sprays and dusts to find a substitute for
ground derris, (2) commercial field tests for the purpose of improving
application methods, (3) the comparison of sprays and dusts, and (4) the
comparison of various dust materials.

Experimental Spray Tests

The spray experiments were conducted in a field of early
Spancross on a light sandy loam in the truck-crop section southwest of
Toledo, Ohio. The following materials were tested as sprays (1) A
crude product containing 60 percent 2-chlorofluorene, 4 pounds, dis-
solved in 2,000 cc. of benzene, per 100 gallons of water; (2) ground
derris root containing 4.7 percent of rotenone, 4 pounds per 100 gallons
of water (standard treatment); (3) ground derris at the same rate for
the first two applications, followed by synthetic cryolite for the last
two applications at the rate of 1 pound per 100 gallons of water; (4)
ground derris for the first three applications, followed by synthetic
cryolite for the. last application; (5) phthalonitrile, 4 pounds per 100
gallons of water; (6) synthetic sassafras oil, 1 part to 800 parts of
water, plus ground derris root, 1 pound per 100 gallons of water; (7)
6 pounds of spray powder containing 5 percent of DDT per 100 gallons of
water; and (8) a nicotine bentonite containing 12.8 percent of nicotine,
applied as a spray containing 0.125 percent of nicotine, which is twice
the usual recommended concentration.







-2-


The first application was made on June 21, while the corn
was still in the whorl stage and averaged 18 inches in height.
Four applications were made, the first three at 5-day intervals.
Bains and cool weather caused a 4-day delay in making the fourth
application. Dates and amounts of rainfall for the spraying season
were as follows: June 28. 0.71 inch; July 4, 1.15 inches; July 7,
1.44 inches; and July 10, 0.37 inch.

Sodium butylhydroxyphenylbenzenesulfonate (Areskap) was
added to all experimental sprays at the rate of 1:2,500 by weight.
Treatments were replicated four times. All plots were laid out in
random blocks, each plot being 4 rows wide and 25 feet long. To
save time and materials, all buffer rows were sprayed with derris
by using the high-clearance, self-propelled machine. This left
only the two middle rows to be treated by hand with the small wheel-
barrow sprayer. The spray was applied at 150 pounds' pressure, all
areas on the plant where the borers were feeding being thoroughly
sprayed. Borer populations in 1943 ran high in the early market
sweet corn. The performance of the spray materials is given in
table 1.

Ground derris spray (standard treatment) gave the highest
borer reductions that we have ever obtained with any insecticide,
notwithstanding the fact that borer populations in the nontreated
plots averaged more than 32 borers per plant. There was no signifi-
cant difference between the performance of the standard ground derris
treatment and those treatments in which cryolite, at the rate of 1
pound per 100 gallons, was substituted for derris in the last appli-
cation or last two applications. Cryolite injured the plants,
causing some of the leaves to turn yellow.

DDT., 2,2-bis(p-~hlorophenyl)-ll,l-trichloroethane, looked
very promising. It reduced the borers 91.9 percent in the plants and
96.1 percent in the ears and did not cause any apparent injury to the
corn plants. Higher concentrations of this insecticide might give
control equal to that with ground derris.







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Although derris (1 lb. per 100 gallons) plus synthetic sassafras oil
(1 part to 800 parts water) gave 85.2 percent borer reduction in the plant
and 89.6 percent reduction in the ears, the sassafras oil caused consider-
able injury at this concentration. Previous laboratory tests shoved sassa-
fras oil to be highly toxic to the corn borer at concentrations of 1:100 to
1:400, but when this material was sprayed on the corn plants at these higher
concentrations severe injury resulted.
The nicotine bentonite, although applied at approximately twice the
nicotine concentration usually recommended, gave only 67.6 percent reduction
of borers in the plants and 82.8 percent in the ears. The cost, as well as
such low control as it gave in this experiment, would limit the value of this
material in its present form for corn borer control.
The crude 2-chlorofluorene used in 1943 was a different product from
that used in 1939 and gave a much lower kill, even though used in higher con-
centration, the reduction in number of borers in the plants being only 50.5
percent. In addition, injury to the plants was observed, probably due to the
benzene used in dissolving the 2-chlorofluorene. The material used in 1943
had a very disagreeable odor and could not be readily dissolved for spraying.
Phthalonitrile not only gave poor control of the borers but caused
considerable injury to the corn plant.
Experimental Dust Tests
All experimental dusts were applied with a hand duster to randomized
plots of the same size and in a layout similar to that described for the ex-
perimental sprays. Applications were made on June 22, June 27, July 2, and
July 10.
At the suggestion of R. C. Roark, five samples of cube powder supplied
by Derris Incorporated, New York, were tested. These contained the following
mixtures with talc:
Rotenone 0.15 percent with 0.75 percent of phenothioxia.
Rotenone 0.15 percent without phenothioxin.
Rotenone 0.25 percent with 0.75 percent phenothioxin.
Botenone 0.25 percent without phenothioxin.
Botenone 0.5 percent alone, to be used as a check.
It was thought that the substitution of phenothioxin for part of the
rotenone might give results comparable to those of straight cube dust con-
taining 0.5 percent of rotenone.
In addition, dust mixtures made up as follows were tested:
Crude 2-chlorofluorene (5.0%) diluted with a pyrophyllite carrier.
Phthalonitrile (0.25%) diluted with a pyrophyllite carrier.
Synthetic sassafras oil, 25 cc. thoroughly mixed in 10 pounds of
pyrophyllite carrier.
As shown in table 2, the 0.5-percent rotenone dust was the most ef-
fective, and the phenothioxin was of no appreciable value, in the concentra-
tion used, as a substitute for rotenone. At the 5.0-percent strength used,
crude 2-chlorofluorene was significantly less effective than the 0.5-percent
rotenone dust. Phthalonitrile and synthetic sassafras oil were about equally
ineffective in controlling the borer. Both 2-chlorofluorene and phthalo-
nitrile injured the corn plants.
None of the dust treatments gave efficient control of the borer, and
owing to the very heavy infestation the yield on all the dusted plots was
greatly reduced.








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Commercial Field Tests of Spray and Dusts

Applied with a Self-Propelled Boom Sprayer-Duster
S
Tests were conducted in two fields of early Spancross and one field
of Earligold to compare spraying with dusting, to compare various dust
materials, and to test improvements in application methods. Borer popu-
lations in these fields were higher than any encountered before im in-
secticide tests. One field contained an average of 7 egg masses per
plant before any hatching occurred. This field at harvesttime averaged
50 borers per plant. Very little untreated early market sweet corn near
Toledo was sold in 1943, owing to heavy borer damage.

Strips 4 rows wide extending completely across the field, and
usually replicated 3 times, were treated with each spray and dust mater-
ial. On the date of first application, June 18, the corn was 26 inches
high and just beginning to tassel. High temperature with much hatching
between the second and third applications necessitated a shortening of
the spray interval.

All spray treatments were made with 4 pounds of ground derris root
(containing 4.7 percent of rotenone) per 100 gallons of water, plus wet-
ting agent (Areskap) 1:2,500. Three solid-cone nozzles per row were used,
the apertures being 3/64 inch for the two outer nozzles and 4/64 inch for
the center nozzle. Spray dosages averaged approximately 170 gallons per
acre per application, applied at a pressure of 150 pounds.

Dust treatments consisted of (1) ground derris in pyrophyllite
containing 0.5 percent of rotenone, (2) dual-fixed nicotine (4 percent
nicotine), and (3) a nicotine bentonite containing 12.8 percent of nico-
tine, diluted to 4 percent nicotine with walnut-shell-flour carrier. One
derris treatment applied with a fan-case housing having a 1-1/2 inch out-
let and tubes leading to the nozzles was compared with another treatment
applied with a fan-case housing having a 2-inch outlet and tubes.

A high-clearance, self-propelled sprayer and duster, constructed
by the Bureau of Plant Industry, Soils, and Agricultural Engineering,
was used to apply the materials. The duster was mounted on the same
chassis as the sprayer. Two nozzles per row were used. Previous to the
dusting season the machine had been calibrated to deliver the desired
dosages of the various dusts.

Field No. 1 Commercial Test

In field No. 1 derris spray was compared with derris dust. It was
planned to apply spray with 0.024 percent of rotenone to these spray plots,,
but owing to an error by the manufacturer in reporting the analysis of one
lot of derris the first and third applications in this field received
0.0396 percent of rotenone. The derris-pyrophyllite dust was applied at
the rate of 50 pounds per acre per application. For two of the treatments,
the occurrence of rain made it necessary to use 2 days to complete a single
application. In all other cases all replicates were treated on the same deay.








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-8-


This field (fig. 1) contained the highest borer populations (4,938
per 100 plants in the nontreated) of the three fields treated. The non-
treatment plots were a complete loss owing to heavy borer damage, net
one ear having been harvested (figs. 3 and 4). The borer-reduction data
obtained from dissection of plants are given in table 3.

Derris spray reduced the population to 270 borers per 100 plants,
a reduction of 94.5 percent in the entire plants and 97.1 percent in
the ears, as compared with the untreated plots (figs. 1 and 2). The
number of No. 1 ears infested per 100 plants was reduced from 102 in the
untreated plots to 36 in the sprayed plots. Practically all the borers
surviving in the latter were in the silks, and very little damage was
done to the kernels (fig. 3).

While the derris dust caused 78.6 percent reduction of borers in
the plants and 79.6 percent reduction of borers in the ears, the numbers
of borers remaining in the plants and ears were still very high, owing to
the extremely heavy borer infestation in this field. These percentage
reductions are higher than are usually obtained with dusts, but they
show the need for more efficient control, especially in cases where
heavy borer populations occur.

Field No. 2 Commercial Test

In field No. 2 the following materials were compared: (1) Derris
spray (0.024 percent rotenone); (2) derris-pyrophyllite dust (0.5 percent
rotenone) applied at the rate of 50 pounds per acre per application,
through 2-inch housing outlets and tubes, so as to have a larger volume
of air carrying the dust but with a reduced velocity; (3) the same dust
applied at the same rate, but with standard duster housing outlets and
tubes (1-1/2 inches in diameter); (4) nicotine bentonite dust contain-
ing approximately 4 percent of nicotine and applied at the rate of 40
pounds per acre per application; (5) dual-fixed nicotine dust contain-
ing 4 percent of nicotine and applied at the rate of 40 pounds per acre
per application.

As shown in table 3, the derris spray was much more effective
than any of the dust materials in reducing the borer infestation in
both plants aed ears. The nicotine bentonite and dual-fixed nicotine
dusts were much less effective than the derris dust in controlling the
borers in both plants and ears, and none of the dust treatments was
satisfactory against the heavy population, which averaged 4,080 borers
per 100 plants in the untreated plots encountered in this field. Only
the derris spray gave satisfactory control in all plots where it was
used.
Approximately 20 percent better control of the borers was ob-
tained where the 2-inch tubes were used than where the 1-1/2 inch
tubes were used to apply the derris dust, at the same rate per acre in
both cases, thus indicating better control with reduced air velocity
in applying dust preparations.






-9-


Yield No. 3 Commercial Test

This was a later field of corn of the variety Zarligold and was
only 12 inches high on June 21 at the time of the first application.
Because of the later planting the infestation in the untreated plots
was only 2,804 borers per 100 plants.

Two treatments were applied to this field, ground derris spray
containing 0.024 percent of rotenone and derris-pyrophyllite dust
containing 0.5 percent of rotenone. The latter was applied at the
rate of 50 pounds per acre per application. As shown in table 3, the
derris spray gave very efficient control, which averaged about 30
percent better in the plants and 27 percent better in the ears than
that given by the derris dust.

Cost of Spray and Dust Materials

With the price of ground derris (5 percent rotenone) at 35
cents a pound, the cost of materials, including the vetting agent,
for four applications of spray per acre totaled $10.73. The cost of
the derris-pyrophyllite dust (home-mixed) for four 50-pound applica-
tions of dust per acre was $8. The cost of dual-fixed nicotine at
15.5 cents per pound totaled $24.80 for four 40-pound applications of
dust per acre. The cost of nicotine bentonite mixed with walnut-shell
flour totaled $23.12 for four 40-pound applications of dust per acre.

Comparative Yields and Income

At the beginning of the experiments a row was staked off in each
plot for use later in determining the size and character of the har-
vest. A record was made of the yield, quality, and disposal of the
corn harvested from these rows by the grower, and of the ears of
salable size remaining on the stalks after the grower had completed
his harvest.

All sprayed ears from the three fields were sold at from 60 to
75 cents per dozen wholesale, and there was a big demand for this
corn. The price for the dusted corn ranged from 25 to 40 cents per
dozen. The yield of ears of salable size, as well as the quality, was
considerably higher for the sprayed corn than for the dusted. Because
of the heavy damage done to the ears by the many borers present, no
corn was picked from any of the untreated parts of the three fields.
Other early fields near Toledo were plowed under before harvesttime
in 1943 because of the heavy borer damage. As shown in table 4, grass
income per acre, based on an assumed normal yield of 800 dozen ears
per acre, ranged from $480 to $600 for the spray treatments and from
$514 to $196 for the dust treatments.





-10-


Table 4.--Yields (number of ears) of early market sweet corn per acre
from insecticide tests in commercial fields at Toledo, Ohio,
1943


Class No. 1,
borer free
or lightly
infested
(no side iniurv)


Class No. 2,
infested,
sold at a
lower Income
rice per acre


Glass No. 3,
unsalable
ears left
in
field


7ield No. 1

Derris spray
Derris dust
No treatment


Yield No. 2 -I

Derris spray
Nicotine bentonite
dust
Derris dust
Dual-fixed nicotine
dust
No treatment


Yield No. 3


9,600


2,592
4.992

4,992
o


Derris spray
Derris dust
No treatment


9,.6oo
0
o


0
5,875
0


4so
196


1,324
1,827
Not counted


_/ Smut was extremely heavy in the nontreated and dusted portions of
this field.,.


Treatment


9,600oo
0
0


0
6,o700
o


$6oo
150
o


570
54
lo4


634
1,083
6, 03.8
6, 48


1,152

1,728
2,016

2,687
, 516
4,516





-11-


For purposes of comparison in table 4 a yield of 800
dozen ears per acre was assumed for the commercial spray
treatments, because practically all ears were salable and in
a normal year 800 dozen would have been a moderate estimate.
Owing to heavy rains and cool weather, however, the stand was
poor and the yield below 800 dozen. The numbers of ears per
acre given for the dusted and untreated plots are in the same
ratio to 800 dozen as the numbers of ears actually harvested
in the dust or check plots were to those actually harvested
from an equal length of row in the sprayed plots.

Harvest data are not so accurate in determining the
effects of an insecticide as are dissection data because they
show only the numbers of ears infested and not the degrees of
infestation. Although all ears harvested in both the derris
and dual-fixed nicotine plots were infested, a comparison of
the umbers of borers in the plants and ears given in table 3
shows that derris dust was more effective than the nicotine
dusts.

Dissection data were obtained prior to harvest dcata,
which probably accounts for the fact that the former indicate
the presence of borer-free ears in the dusted plots whereas
the latter do not.

Some conclusions drawn from the commercial-scale tests
are (1) that derris spray was considerably more effective in
corn borer control than any of the dust materials used, (2)
that derris dusts were more effective than nicotine dusts, (3)
that none of the dusts tested were satisfactory when dealing
with high borer populations, and (4) that very heavy infesta-
tions of the borer can be satisfactorily and profitably con-
trolled in early market sweet corn with ground derris spray.

Summary

The following materials were applied as spreays in small
plots in 1943 to find a substitute for ground derris spray or
to lower the cost of treatment: (1) Crude 2-chlorofluorene.
(2) derris root (standard treatment for comparison), (3) derris
for the first two applications followed by synthetic cryelite
for the last two. (4) derris for the first three applications
followed by synthetic cryolite for the last application, (5)
phthalonitrile, (6) synthetic sassafras oil plus der.-is, (7)
DDT, and (8) a nicotine bentonite containing 12.8 percent of
nicotine.




-12-


The derris-cryolite combination gave high control, but
some plant injury was caused by the cryolite. Both phthalonitrile
and the synthetic sassafras oil-derris combination injured the
plants. The most promising of the new materials tested was DDT,
which gave satisfactory control and no injury to the corn plants.

The following dusts were compared in small-plot tests:
(1) Cube dust containing 0.5 percent of rotenone, (2) cube dust
containing 0.15 percent of rotenone plus 0.75 percent of phenothiexin,
(3) cube dust containing 0.15 percent of rotenone without pheno-
thioxin, (4) cube dust containing 0.25 percent of rotenone plus 0.75
percent of phenothioxin, (5) cube dust containing 0.25 percent of
rotenone without phenothioxin, (6) crude 2-chlorofluorene (5.0 per-
cent) dusts, and (7) a 0.25-percent phthalonitrile dust.

None of the foregoing dusts proved satisfactory from the
standpoint of borer control. Phthalonitrile and crude 2-bchloroflue-
rene both injured the corn plants. Phenothioxin vas of no appreci-
able value, in the concentrations tested, as a substitute for rote-
none in the form of cube dust.

Comparisons were made, in three commercial fields, of spray
and dust materials applied with a self-propelled sprayer and duster.
Borer populations in the nontreated portions of these fields ranged
from 2.804 to 4,938 per 100 plants.

Very satisfactory control was obtained with ground derris
spray in all three fields. Borer reductions produced by the spray
treatments ranged from 90.5 to 94.5 percent in the plants and from
94.3 to 97.3 percent in the ears.

Dust treatments in commercial fields produced borer reduo-
tions ranging from 37.9 to 78.6 percent in the plants and from 46.1
to 79.9 percent in the ears. With high borer abundance in 1943
these reductions meant high borer populations remaining in the plants
and ears after the dust treatments.

Gross returns per acre ranged from $480 to $600 for the spray
treatments and from $54 to $196 for the dust treatments.

The conclusions drawn from the 1943 commercial tests are as
fellows: (1) Derris spray was considerably more effective in corn
borer control than any of the dusts used; (2) derris dusts were
more effective than nicotine dusts; (3) none of the dusts tested
were satisfactory when dealing with high borer populations; (4) very
heavy infestations of the corn borer can be satisfactorily and
profitably controlled in early market sweet corn with ground derris
spray.







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Figure 1.-Nontreated strip adjacent to a derris-spr-iyed strip,
photographed at the same time after harvest in commercial field
No. 1 (compare with fig. 2). Toledo, Ohio, 1943. (Photo-rap'h by
Bureau of Plant Industry, Soils, arid. Agricultural Engineering).





































Figure 2.--Derris-sprayed strip Just after harvest in commercial
field No. 1 (compare with fig. -l). Toledo, Ohio, 1943. (Photograph
by Bureau of Plant Industry, Soils, and Agricultural Engineering.)






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~

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I I













Figure 3.--ars from the nontreated strip (above) and from the derrie-
sprayed strip (below) in field No. 1. These were taken at the time of
the fifth and last picking from the sprayed plot and are more irregular
and somewhat smaller than the bulk of harvest. No marketable ears were
produced on the untreated strip. Toledo, Ohio, 1943. (Photograph by
Bureau of Plant Industry, Soils, and Agricultural Engineering.)





UNIVERSITY OF FLORIDA

3 1262 09228 0048


1igure 4.--Ies picked from 15 consecutive plants in the nontreated
strip in commercial field No. 1, showing borer injury to the husks,
and. small ears caused by the heavy borer population in the plants.
Toledo, Ohio, 1943. (Photograph by Bureau of Plant Industry, Soils,
and, Agricultural Mpgineering.)