Evaluation of Insecticides for Control of Lesser Cornstalk Borers on Peanuts, 1992

Abstract

Abstract This test consisted of two parts, a field application of the granular insecticides and a laboratory bioassay. Insecticides were applied to conventionally planted and tilled peanuts in a light loamy sand soil at the Wiregrass Substation of Auburn University at Headland, AL. Twelve treatments and a control were replicated four times in randomized complete block design. Each plot was six rows wide (36 in row spacing) and 50 ft long. Insecticides were applied, at flowering, on 30 Jun with a small-plot granular applicator in a 7 inch band over the row. A second application of Dyfonate 20G and PCB-coated Dyfonate was made 27 d after flowering on 27 Jul. The soil sample was taken from each plot once per wk by collecting 3 subsamples (12-in wide by 4-in long by 1-in deep) from within each plot. The soil sample was collected from underneath the peanut canopy by removing the plant. Soil samples were taken to the laboratory and refrigerated at 0°C until assayed the following week. Soil from each treatment was air dried to <1.0% moisture and placed in 1-oz plastic diet cups at a depth of 0.5 in. First instar larvae placed in these cups were provided diet as a continuous food source. Pesticide efficacy was evaluated by exposing 36 larvae (4 replicates times 3 cups per replicate times 3 larvae per cup) to each soil sample or treatment. At the end of a 72h exposure, the number of live and dead insects were counted.