PROTECTING THE EARS OF SUEET CORN FROM INSECT
DAMAGE IN THE EVERGLADES AREA
Norman C. Hayslip and W. H. Thames, Jr.
This report is made available as a guide to
commercial growers of sweet corn in the Ever-
glades area for use in formulating an insect
control program. The information represents
the best that is available to date on the basis
of experiments conducted at Everglades Experi-
ment Station and Indian River Field Laboratory.
EVERGLADES STATION MIMEO REPORT 55-11
Belle Glade, Florida .
April 22, 1955
PROTECTING THE EARS OF SWEET CORN FROM INSECT
DAMAGE IN THE EVERGLADES AREA
Norman C. Hayslip and W. H. Thames, Jr.Q/
Caution: Parathion and DDT are reconrmended for use on sweet corn.
These insecticides must be used carefully, especially
parathion dust and spray. Read precautions on labels
and follow directions.
I- CONTROL OF INSECTS DURING THE TASSELING PERIOD TO REDUCE MIGRATION TO THE CORN
A- Corn-silk fly Plants should be checked when the tassels begin to appear
for restless inch long flies with distinct black cross stripes on the wings.
These insects run up and down the plants, periodically stretching their wings
outward. Use 2 percent parathion dust at 30 pounds per acre, or 2 pounds of
15 percent wettable parathion per 100 gallons of water to kill flies before
they deposit eggs in tips of the young corn ears.
B- Fall armyworms and corn earworms in the buds and tassels of corn.* The buds
and young tassels should be inspected as soon as the first tassels can be
seen. Large worms are easily detected, however very small ones feeding in
the tassels may be overlooked unless the tassels are carefully examined, If
worms are present, dust or spray every two days while the tassels are grow-
ing out and until they are open. Two or three applications will be necessary.
The tassels push the worms out of the buds and expose them to the insecticide.
If not controlled at this time they will migrate to the developing ears.
Toxaphene or DDT 10 percent dust, or 2 pounds 50 percent wettable per 100
gallons water is suggested if no aphids or corn-silk flies are present. Other-
wise, 2 percent parathion dust or 2 pounds of 15 percent wettable parathion
per 100 gallons of water should be used.
C- Aphids Aphids often become established in the corn tassels, and migrate to
the ears when the tassels mature. A check should be made when first tassels
appear. If aphids are present, spray or dust with parathion at 2-day inter-
vals as the tassels emerge and open. Two or three applications should be
Note: A dust mixture of 5 percent DDT and 1 percent parathion,
or a spray mixture of 2 pounds of 50 percent wettable DDT
and 1 pound of 15 percent wettable parathion may be used
at 2-day intervals as the tassels appear forcontrol of
all of the above insects during the tasseling period,
II- PROTECTION FROM INSECTS DURING THE SILKING PERIOD.
A- Corn-silk fly and aphids These insects should be eliminated before the
silks appear, however, if they re-infest the crop parathion is recommended.
Use 30 pounds per acre of 2 percent parathion dust as often as is necessary
to keep the adult silkflies eliminated, and to hold the aphid population low.
7 Associate Entomologist, Indian River Field Laboratory and formerly Assist-
ant Entomologist, Everglades Experiment Station, respectively.
- 2 -
B- Corn earworm If there have been no insecticide treatments during the
tasseling period, a pre-silking treatment is recommended about 2 days
before the first silks appear.
1- Fall, winter and early spring corn (light to moderate infestations
of corn earworms can be expected during these periods).
a- Dust: Apply one of the following formulations every 2 days
from time of first silks, until silks are brown.
About 8 applications, 25 to 30 pounds per acre re-
quired. Direct the dust at the silks&
1- Ten percent DDT.
2- Two percent parathion.
3- Five percent DDT plus one percent parathion.
b- Spray: Six to seven applications at 2-day intervals.
First application when first silks appear.
Direct spray to thoroughly wet silks.
1- Three to four quarts per acre of 25 percent
emulsifable DDT in 50 gallons of water ap-
plied to one acre.
2- Late spring corn (severe infestations of corn earworms can be
expected during this period and control is therefore difficult.
It is suggested that growers may want to avoid planting late
spring corn which silks in May and June in order to escape
these severe earworm populations).
a- Dust: Apply one of the following formulations every day
from the time of first silks, until the silks are
brown. About 10 to 12 applications required at
30 to 35 pounds per acre.
1- Ten percent DDT.
2- Five percent DDT plus one percent parathion.
3- Two percent parathion.
b- Spray: Apply 5 treatments at 2-day intervals, 50 gallons
per acre. First treatment one day after first
silks appear. Arrange spray nozzles to thoroughly
wet silks. Do not spray entire plant.
1- Four quarts of 25 percent DDT emulsion and 2.5
gallons of mineral oil per acre per treatment.
Mix DDT and oil together in stock solution, and
mix 3.5 gallons of the stock solution with 46.5
gallons of water. Commercial mixtures of the
DDT-oil formulas are available at some supply
houses. Do not use DDT-oil except for late
spring corn which is threatened by heavy ear-
worm attack. It gives the most effective con-
trol, however, a yield reduction may occur in
some instances. Do not mix this formula with