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CF Central Science
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CENTRAL FLORIDA RESEARCH AND EDUCATION CENTER
Sanford, Florida OCT 23 1987
Research Report SAN 86-08 S1 p d9 rida
EVALUATION OF INSECTICIDAL SEED COATINGS FOR THE CONTROL OF FALL
ARMYWORM ON SWEET CORN AND FIELD CORN SEEDLINGS GROWN IN
SANDY AND ORGANIC SOIL, EXPERIMENT II, 1984
G. L. Leibee
Treated seed for this experiment was provided by Union Carbide.
The treatments consisted of 'Jubilee Fl' sweet corn seed treated with UC
80502 at 8 and 16 oz of ai/cwt, Orthene 80 seed protectant (the
standard) at 8 oz/cwt, and an untreated check; and 'AD 3995 R23' field
corn seed treated with UC 80502 at 4 and 8 oz of ai/cwt., Orthene 80
seed protectant (the standard) at 8 oz/cwt, and an untreated check.
Eighty 4-inch plastic pots of unsterilized soil were prepared; 40 pots
of Myakka fine sand from the Central Florida Research and Education
Center and 40 pots of Lauderhill muck from Zellwood, FL. Each of the 8
treatments was planted in 5 pots of each soil type. Five seeds were
placed per pot 3/4 inch deep on October 11, 1984. The entire experiment
was conducted in the greenhouse. All pots were watered equally when the
soil surface was dry. The corn plants began to spike on October 14.
Each plant was infested with 2 first instar fall armyworm, Spodoptera
frugiperda, larvae on October 19 when the corn was in the 2-3 leaf
stage. The pots were spaced about one foot apart to prevent migration
of the fall armyworms between pots. On October 22, the sweet corn grown
in the sand was 7 inches tall and had 3 leaves, and that grown in the
muck was 7.5 inches tall and had 4 leaves, while the field corn grown in
the sand was 11.5 inches tall and had 3-4 leaves, and that grown in the
muck was 11.5 inches tall and had 4-5 leaves. The plants were rated for
damage on October 23 as follows: 1=no damage; 2=damage to outer leaves
only; whorl clean; and 3=whorl damaged.
The results of this experiment are presented as the mean percentage
of the plants per pot with a damage rating of 3. A damage rating of 3
indicated that the first instar fall armyworm larvae survived long
enough to damage the new growth that occurred during the infestation
period of 4 days. All the seed treatments significantly (P<0.05)
reduced the amount of damage when compared to the untreated check. All
the seed treatments were equally effective in the sand, and there were
no apparent differences due to the kind of corn. The muck reduced the
effectiveness of some treatments when compared to the sand results.
Also, the kind of corn had a significant (P<0.05) effect on the efficacy
in the muck. Specifically, the effectiveness of Orthene seed coating
was greatly reduced and the effectiveness of UC 80502 at 4 oz. was
increased in the field corn relative to the sweet corn. It is
interesting to note that within each type of corn for both soil types,
the higher rate of UC 80502 was less effective than the lower rate, but
this difference was significant (P
phytotoxicity was observed.
Evaluation of seed coatings for the control of fall armyworm on
sweet corn and field corn seedlings grown in sandy and muck soils.
Treatment-oz. of % with damage rating of 3~
Crop ai/cwt of seed Sand Muck
UC 80502, 8 oz.
UC 80502, 16 oz.
UC 80502, 4 oz.
UC 80502, 8 oz.
Means within each column followed by the same letter are not
significantly different at the 0.05 level by DMRT. Analysis was
performed on transformed (arcsine) data.