Investigations of sprays for control of the European corn borer, Toledo, Ohio, 1945-1946

\T AI" " E-743


United States Department of Agriculture
Agricultural Research Administration
Bureau of Entooilogy and Plant Quarantine



ImSTIGATIONS OF SPRAYS FOR CONTROL OF THE URJBOPEA CORN BORDER,
TOLEDO, OHIO, 1945-1946

By D. D. Qiestel and B. V. Connin,
Division of Cereal and Forage Insect Investigations


Investigations of insecticides applied as sprays for control of
the European corn borer (&Eausta nubilalis (Hbn.)) were continued
during the seasons of 1945 and 1946 in the vicinity of Toledo, Ohio,
and the results obtained are presented herewith.

Small-Plot Tests

aSmall plots were laid out in randomized blocks, each plot being 4
rows wide and 20 feet long, and each treatment was replicated 4 times.
A wheelbarrow sprayer powered with a gasoline engine and equipped with
nozzles that produce solid cones of spray was used in the application of
water suspensions. All buffer rows were treated with a spray containing
ground cube root (4.8 percent rotenone) applied with a self-propelled
boom sprayer. All the insecticides were tested as water suspensions,
and sodium butylbydroxyphenylbenzene sulfonate (Areskap) was used as the
wetting agent at the rate of 1/3 pound per 100 gallons of water. The
plants were thoroughly sprayed, enough spray being applied to cause free
run-off at the base of each plant. The quantities used were increased
during the season as the plants grew larger. No accurate record of the
gallons used per acre was practical, but the dosage was estimated at
150-175 gallons per acre in 1945 and 170 gallons in 1946.

In 1945 borer development was late but corn development was later.
The egg-hatching period began in the earliest fields on June 25, or 10
days later than in 1944, and ended after July 11, 11 or more days later
than in 1944. The first spray application was made on June 29, when the
corn was 9 inches high. This is in contrast with the 1944 season, in
which the first application was made on June 17, when the corn was 36
inches high. Additional applications in 1945 were made on July 4, 9,
and 14. Only slightly more than 1 inch of rain fell during the spraying
season.

In 1946 egg hatching began on June 25, and the first spray was
applied on June 28, when the corn was 38 inches high with tassels begin.-
ning to emerge. Three additional applications were made on July 3, 8,
and 13. At the time of the second application the corn was fully tasseled
and silking.






-2-


In both years 100 corn plants, 25 from each plot, for each treatment
were dissected at the roasting-ear stage to determine the effectiveness
of the treatments. The results are presented in tables 1 and 2.

In 1945 the compounds l-isobutyryl-2-phenylhydrazine and 1-phenyl-
2-(phenylsulfonyl) hydrazine were among the more effective of the insecti-
cides tested. 1-Trichloro-2,2-bis(3,5-dichloro-2-hydroxyphenyl)-ethane,
tetrachlorodiphenylethane, benzene hexachloride, and 1-phenyl-semioxama-
zide were apparently somewhat less effective, though not significantly so,
at odds of 19 to 1. Both bis(3,5,6-trichloro-2-hydroxyphenyl)methane and
l-phenyl-2-(2-tolysulfonyl)hydrazine greatly reduced borer populations in
both plants and ears, but were significantly less effective than the first
eight materials listed. However, a rather heavy dosage of all these
chemicals except belizene hexachloride was used.

The particle size of the high-rotenone (9.6 percent) cube powder tested
in 1945 was very small (300-500 mesh). Although this material gave satis-
factory control, it did not reduce the borer population in the plants so
much as did the cube of lower rotenone content which had a somewhat larger
particle size.

Byania, l-trichloro-2 2-bis(3,5-di chloro-2-hydroxyphenyl) ethane,
l-phenyl-2-(phenylsulfonyl)hydrazine, cube, and DDT gave good spray sus-
pensions. The remaining materials gave poor to medium suspensions.

Of the nine materials tested in 1946, five showed very promising
results. Chlorinated camphene and 2,2-bis(3-bromo-5-chloro-2-hydroxyphenyl)-
1-trichloroethane were both about as effective as DDT but were used at
considerably heavier dosages.

The sample of methoxy analog of DDT (trichloro-bis(methoxyphenyl)-
ethane) used in these tests was highly effective, although a different,
highly purified sample that was tested at the same strength in the labora-
tory during the winter of 1945 caused no appreciable mortality of corn
borer larvae. In view of these results, a comparative test of both samples
was run in the laboratory. The 1945 material again caused no mortality,
whereas the 1946 material was quite toxic at low concentrations. This
discrepancy was apparently due to some difference in the preparation of the
two samples.














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In 1945 the corn plants showed moderate injury by bis(3,5,6-
trichloro-2-hydro3yphenyl)methane, l-trichloro-2, 2-b i s(3, 5.i-dichloro-
2-hydrozyphenyl)ethane, l-'phenylsemioxamazide, 2-isobutyryl-2-
phenylhbydrazine, l-phenyl-2(phenyl ulfonyl)hydrazine, and l-'phenyl-
2-(p-tolylsulfonyl)bydrazine 2 days after the first application. On
July 17, 3 days after the last application, 1-phenylsemioxamazide and
bis(3,5, 6-trichloro-2-hydroxyphenyl)methane showed moderate injury, and
1-t richloro-2, 2-mbis(3, 5-dichloro-a-hydroxrphenyl)ethane and l-phenyl-
2-( -tolylsulfonyl)hydrazine showed slight injury. There was no apparent
redaction in yield as a result of the use of any material tested.

In 1946, prior to the actual spraying season, the plytotoxicity of
all new materials to be used in the small-plot tests was tested by apply-
ing them to young corn plants in the field with a hand sprayer. Three
successive applications were made, the first on May 29, when the plants
were 8 inches high, and the others on May 31 and June 3. The materials
were applied in suspensions of 8, 4, and 2 pounds per 100 gallons of
water, in sufficient quantity to provide run-off. None of them caused
any observable injury to the plants.

In experiments conducted during 1946 with a field-model aerosol
generator, highly refined airplane-engine oil applied as an aerosol
produced severe burning. Crude soybean oil caused no injury when applied
with the same machine, even when the plants close to the machine were
covered with sufficient oil to cause run-off, A powder containing 50
percent of DDT applied as a water suspension at the rate of 1/2 pound of
the mixture per gallon of water caused no injury to corn or pepper plants
when applied with the aerosol generator.

As a further test of tolerance of corn to exceptionally high dosages
of DDT, the two buffer rows between each treated plot were sprayed four
times at the very heavy rate of 7 pounds of DDT per acre, making a total
of 28 pounds per acre. These buffer rows were watched closely for injury
to the plants, but none was observed.

Field Tests

DDT, 4ania. and rotenone were tested in 1945 and 1946 in commercial
fields containing the earliest planted, most rapid growing market sweet
corn. Strips four rows wide extending across the field, replicated three
times for each treatment, were sprayed with a two-row self-propelled
machine equipped with a stalk-gathering attachment and nozzles which pro-
duced solid cones of spray. The stalk gatherers consisted of metal rods,
one pair to each row, with one end fastened to the machine so that they
were freely adjustable in any direction. These rods lifted the lower
leaves of the plants and tillers and held them directly under the spray
nozzles as the sprayer passed over the plants. If the sprayer was guided
off the row, the gatherers bent the plants into the spray from the nozzles.









o tyitdd. as npij & ispat-isonis in 19"4^-&
i,.ji a I s~~otair 2.,g -5 per.ant of D on fulldrs earth, ground
at it a of s.A p ..it aund ground uube root containing 4. 8 percent
of rotinua,. The same materials were tested in 1946 except that the WD
dust contained. 50 percent of MD. Ultrawet (an aromatic monosodium
sulfonate) was used as the wetting agent in all sprays at the rate of
1/3 pound per 100 gallons of water,

In 1945 the fiLat appi-Lcation was made on June 25, when the corn was
aopproximately 14 ichas high and in the whorl stage. MAditional sqplica-.
tione were ao.e orn Juno 30 and July 5 and 10. From 170 to 190 gallons of
spray ex'e applied per togr&eiEqplication, larger quantities being used as
the plants grow larger. In 1946, all four applications were made at the
untiforu rai of 1T5 gallons per &:;ea At the time of the first applies'-
tion, June 26, the pluts were 38 inches high with the tassels beginning
to emerge. MiMitional applications were made on July 1, 6, and. 10, and at
the roasting-ear stage in both years a total of 50 plants were dissected
from the three replicate strips for determining the borer populations*.
The r'eolts are given in table 3.

A in the "alldlot tfrats, the DDT micronised on fullerts earth
g&ve the beet control in both years, evren though the dosage was only
1/2 pound of DDT por acre in 1945. The results obtained with kania were
practically the sam as those obtained with rotenone in 1945, each giving
satisfactory control, but the Ryania appeared to be somewhat more effective
in 1946.

Under the cwaapatively heavy infestation in 194 there were only
8 No. 1 borer-fres ears per 100 plants in check plots as compared with
96 in the plots treated with MW.

The higher control obtained in 1945 than in 1946 with 1fania and
rot .ic.ne ay have been due partially to the fact that the corn was in
the whzorl stage in 1945 at the time the applications were made, as higher
control is usually obtained at this stage than at the tasseling and
Otlkin3d atagun,

Jsiinee of MT on Sprayed. Corn Plants

*tpl z;' gras&n ar. plants that had been treated four times with
)DM at lpuiwiz. and '-pouad dosages in the amall-plot tests were taken at
.oagtit. -di .ryt time and sent to the Division of Insecticide
Iuw tfigati..i f,1. dte',iiat.f&tion of 3DT residues. The chemical analyses
showed that, baisd oa the green heights and the organic chlorine founi,
0.8 p.y,. of DW s pieseat on the unhasked ears and 17.8 pop-a. on
the l&6twas &tJ stalkb of the plants that had been prayed with WT at a
total of 4 pomiz&s per acre, and 15.0 p.p.uo on the unbusked ears and
190,2 p.p.m. on the l.,vsas and stalks of the plants that had. been sprayed
with ef dtI a t~tal .128 ^ eouiida per acri&.





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UNIVERSITY OF FLORIDA

3 1262 09239 2082


Summary

Investigations of insecticides appliable as sprays for control of the
European corn borer (Pvyrausta nubilalis (Hbn.)) were continued during the
seasons of 1945 and 1946 in the vicinity of Toledo, Ohio. In small-plot
tests thirteen preparations applied with a wheelbarrow sprayer in 1945 re-
duced the borer population in the plants 89 percent or more. Of the new
materials tested in the small-plot teats in 1946, five gave satisfactory
control-technical DDT micronized on fuller's earth, l,l-dichloro-2,2-bis-
(p-chlorophenyl)ethane, chlorinated camphene, 2,2-bis(3-bromo-5-chloro-2-
hydroxyphenyl)-l-trichloroethane, and trichloro-bis(methosyphenyl) ethane.
None of the five caused spray injury when applied to growing corn plants.

Highly refined airplane-engine oil, one of the carriers used with DDT
as an aerosol, caused severe injury to corn plants, but crude soybean oil
similarly used caused no apparent injury.

Twenty-eight pounds of DDT per acre applied in four applications as a
water suspension caused no observable injury to growing plants.

In comparisons of DDT, Rania speciosa, and cube powder applied with
a self-propelled power sprayer in commercial fields of early-market sweet
corn, DDT was the most effective against the borer although very good con-
trol was obtained with the other two.

DDT residues amounting to 0.8 and 15.0 p.p.m. were present on roasting
ears taken from plots that had been sprayed with DDT at totals of 4 and 28
pounds per acre. Samples of leaves and stalks from the same plots bore DDT
residues amounting to 15.0 and 190.2 p.p.m., based on their green weights.