Efficacy of Bt Corn Hybrids Compared to Pre-Plant, Planting-Time, Pre-Emergence, and Rescue Insec-Ticide Treatments for Black Cutworm Control, 1997

Abstract

Abstract Each plot consisted of four rows by 40 feet long, with treatments applied tc the center two rows, leaving two untreated rows between each plot. A RCB design with four replications was used. Two untreated check plots were includec in each replication and were averaged for ANOVA. Fifteen third- to fourth-instar laboratory reared BCW larvae were placed in each barrier arena on 2’. May. Corn plants within each barrier were in the Vl-2 stage (Iowa State Special Report, No. 48), at the time of larval release. The larvae used in this tes were supplied by Dr. Armon Keaster and Mary Jackson of the University of Missouri. Pre-plant insecticide treatments were applied with a CO2 back-pack sprayer utilizing four 8003VS nozzles calibrated to deliver 18.7 gpa at 25 psi, broadcast over what would become the center two rows of the four-row plots Planting-time granular insecticides were metered through Noble units mounted on each of the center 2 planter units. These granules were applied in a 7-incl band ahead of the firming wheels on the planter. Spring tines mounted behind each planter unit were used to incorporate insecticides into the soil. Planting time microtube liquid treatments of (Regent 4SC 0.13 lb(AI)/acre and Regent 4SC 0.13 lb(AI)/acre + Pounce 3.2 EC 0.05 lb(AI)/acre) were applied usinj microtubes directed into the furrow and calibrated to deliver 1.0 gpa at 20 psi. Planting-time banded liquid treatments of (Regent 4 SC 0.13 lb (AI)/acre anc Regent 4 SC 0.13 lb (AI)/acre + Pounce 3.2 EC 0.05 lb (AI)/acre) were applied with two 80067 TeeJet nozzles (1 per row), in a 7-inch band, with a compressed-air system calibrated to deliver 3.3 gap at 16 psi and a speed of 2.5 mph. Pre-emergence insecticide treatments were applied with a CO, back-pack sprayer utilizing 4 8003VS nozzles calibrated to deliver 18.7 gpa at 25 psi, over the center two rows of the four-row plots. Rescue insecticide treatment; were applied utilizing the same equipment used for the pre-emergence treatments over the center two rows of the four-row plots.