Field Corn, Wireworm Larval Control, 1994

Planting-time soil insecticides and seed-treatments were evaluated for wireworm control in a silt loam field near Farmington, IA. The field had been no-till planted into corn stubble and required replanting due to severe wireworm damage. The test plot was no-till planted 12 May into an area of the field that had received the most damage. The experimental design was a RCB with 4 replications. Treatments were applied to single, 50-ft length rows with 30-inch row spacing. Granular insecticide formulations were applied with modified Noble metering units that had been laboratory-calibrated to accurately deliver material at a speed of 4 mph. The applicators were mounted on a 4-row John Deere Max-Emerge 7100 integral planter. Liquid formulations were applied with a compressed-air delivery system built directly into the planter; 8003E nozzles delivered 13 gpa at 23 psi. Each row was constantly monitored to ensure that insecticide was being correctly applied at all times. Planter-mounted drag chains were used for incorporation. Seed treatments were assigned to extra, individual seed hoppers. Following corn emergence, stand counts were taken from 1/1000 acre per treatment. Seeds/seedlings were then carefully extracted from two, 1-m sections of each treatment row, inspected for wireworm feeding damage, and rated on the following 1 to 4 damage scale: (1) seed/seedling undamaged, (2) seed/seedling damaged but plant established, (3) seed/seedling damaged, plant showing some signs of stress, (4) seed/seedling damaged, no plant or questionable establishment Insecticide efficacy was analyzed using ANOVA and means were separated with Ryan’s Q test (REGWQ).