Chemigation Applications for Second-Generation Corn Borer Control, 1988

Abstract

Abstract This experiment was conducted in furrow-irrigated corn in Finney County, Kans. Standard and simulated chemigation applications of corn borer insecticides were made to evaluate their efficacy under 2 methods of application. Untreated and miticide-treated (Di-Syston) plots were included as controls. Treatments were arranged in a randomized complete block design with 4 replicates. The plots were 4 rows wide (10 ft) and 45 ft long. The standard insecticide applications were made with a high-clearance sprayer using a 10-ft boom with 3 nozzles directed at each row (one nozzle directly over the row and 2 suspended on 18-inch drop hoses). The sprayer was calibrated to deliver 40 gal/acre with 30 psi of CO2 pressure. The simulated chemigation applications were made using 3 Delvan 100/140, 3/4-inch raindrop nozzles mounted on the high-clearance sprayer at tassel height between the rows. This system was calibrated to deliver 5,400 gal/acre on the 2 center rows (equivalent to a 0.2-inch irrigation). Chemicals were added to 200 gal of water in the main tank of the sprayer and agitated by recirculation and applied within 20 min of mixing. The treatments were applied on 4 Aug and some were retreated on 12 and 17 Aug. The timing of applications was based on the Kansas State University SWCB and ECB models and the presence of corn borer eggs in the field. Evaluations were made 21-27 Sep by dissecting 10 corn plants from each plot (5 consecutive corn plants from each of the 2 center rows). The number of larvae of each species and the length of tunneling was recorded for each plant.