THE EFFECTS OF THE SECOND GENERATION EUROPEAN CORN BORER, OSTRINIA NUBILALIS (HUBNER) (LEPIDOPTERA: PYRALIDAE) ON HARVEST LOSSES IN FIELD CORN
Abstract
Research was conducted in 1981 and 1982 to quantify losses due to stalk breakage and dropped ears caused by 2nd-generation European corn borer under present corn production systems in Indiana. Insecticide treated and untreated portions of corn fields were compared at all test locations. Artificial infestation was achieved by pinning 2 egg masses (near hatching) through the leaf midrib of the ear leaf during the period of pollen shed. Chlorpyrifos (0.96 kg a.i./ha) was applied 1 or 2 times using a Solo 425('R) Knapsack sprayer and a Hi-Boy('R) sprayer in 1981 and 1982 experiments, respectively. Control was determined by counting entrance holes in the stalk and cavities caused by corn borer feeding in the stalk and ear shank. Stalk breakage before harvest was categorized as to its location in the stalk as top, above-ear, below-ear and bottom. Plants with visible ear shank damage were noted. Ears dropped to the ground before harvest and unpicked ears after harvest were counted and collected. Number of entrance holes was reduced by insecticide application in all experiments. The number of stalk cavities was lower in insecticide-treated plots than in untreated plots in all experiments, although not significantly different in the 1981 experiment. Insecticide application had an effect on number of the borer cavities in the ear shank only in the 1981 experiment. Grain weight was higher in plots with insecticide application than no-insecticide treatment in 1981. No difference in grain weight was detected in 1982. The number of insecticide treatments did not affect stalk breakage in any experiment. Stalk breakage in the above-ear, below-ear and top areas did not affect mechanical picking since the highest ear losses, were associated with stalks broken in the bottom area of the stalk. Ears dropped before harvest in all experiments were negligible.
Degree
Ph.D.
Subject Area
Entomology
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