Second Generation European Corn Borer Control, 1994

Abstract

This study was conducted in a furrow-irrigated corn field at the Southwest Research-Extension Center, Finney County, KS. Treatments were arranged in a RCBD with 4 replications. Plots were 4 rows, (10 ft) wide and 50 ft long, with a 4 row border of untreated corn on each side and a 10 ft alley at each end. The single application was made on 28 or 29 Jul, while the double corn borer treatments were made on 22 Jul and 1 Aug. The simulated chemigation applications of insecticides were made using 3 Delavan 100/140, % inch raindrop nozzles mounted on a high clearance sprayer at tassel height between rows. This system was calibrated to deliver the equivalent of 0.21 in irrigation on the 2 center rows (5730 gal/acre). The standard insecticide treatments were applied with a high clearance sprayer using a 10 ft boom with 3 nozzles directed at each row (1 nozzle directed at the top and one on each side of the row on 16-inch drop hoses directed towards the ear zone). The sprayer was calibrated to deliver 20 gal/acre at 2 mph and 40 psi. The granular applications were made with electric Gandy® boxes mounted on the high-clearance sprayer using a 7 inch bander directed over each row. Corn borer control was evaluated by dissecting 15 plants per plot between 23 and 30 Sep to determine the number of corn borer larvae and length of tunneling per plant. Grain yield was determined by machine harvesting the two center rows in each plot and correcting to 15.5% moisture.

Verification of a European Corn Borer (Lepidoptera: Crambidae) Loss Equation in the Major Corn Production Region of the Northeastern United States

“…This was a major step forward in European corn borer management because Bt corn provided season-long protection of corn plants at a much lower cost than would be incurred with spraying (about one-Þfth the cost of an insecticide application). Bt corn hybrids also reduced European corn borer populations between 96 and 99% compared with insecticide applications that reduced population levels from Ͻ50 to 95%, depending upon, for example, timing and amount applied (Ostlie et al 1997, Buschman et al 1995. The combination of reduced cost and increased efÞcacy resulted in substantially lower economic thresholds and an increased percentage of acreage (Ϸ80%) that could justify the use of Bt corn (Calvin 1995).…”