Evaluation of Insecticides for Control of Lesser Cornstalk Borer on Plants, 1989

Abstract

Abstract This test consisted of 2 parts, a field application and a laboratory bioassay. The field application was applied to conventionally planted and tilled peanuts in a light loamy sand soil at the Wiregrass Substation of Auburn University at Headland, AL. Ten treatments and a control were replicated 3 times in a randomized complete block design. Each plot was 6 rows wide (36 inch row spacing) and 50 ft long. Granular treatments were applied, at pegging, on 30 Jun with a small-plot granular applicator in a 7 inch band over the row. Penncap M was applied over the row once a week on four consecutive weeks beginning 30 Jun. It was applied, in water, using a boom sprayer with one hollow cone nozzle/row at 40 psi, delivering 8 gal/acre. One soil sample was taken from each plot at 0, 6, 11, 19, 25, 39, 53, and 67 DAT. Each soil sample was taken by collecting 3 subsamples (12-inch wide by 4-inch long by 1-inch deep) from within each plot. Sampled areas were flagged to prevent resampling. Soil samples were taken to the laboratory and refrigerated at 0°C until use. Soil from each treatment was air dried to <1.0% moisture and placed at a depth of 0.5 inch in 1-oz plastic cups. Larvae were placed in these cups and provided sorghum seedlings as a continuous food source. Pesticide efficacy was evaluated by exposing 27 first-instar lesser cornstalk borer larvae (3 replicates times 3 cups per replicate times 3 larvae per cup) to each soil sample or treatment. At the end of 72 h exposure, the number of live and dead insects was counted.