Corn Borer Insecticide Efficacy Trial, 1990

Abstract

Abstract This experiment was conducted in a furrow-irrigated corn field at the Southwest Research- Extension Center. Treatments were arranged in a randomized complete block design with 4 replications. Plots were 4 rows wide (10 ft), 50 ft long with a 10 ft border of untreated corn on each side and a 10 ft alley between plots. The simulated chemigation applications were made using 3 Delavan 100/140, .75- inch rain drop nozzles mounted on a high clearance sprayer at tassel height between rows. This sytem was calibrated to deliver the equivalent of a 0.2 inch irrigation on the 2 center rows (5227 gal/acre). The standard treatments were applied with a high clearance sprayer using a 10 ft boom with 3 nozzles directed at each row (1 nozzle directly over the row and 1 on each side of the row on 18 inch drop hoses). This system was calibrated to deliver 20 gal/acre using a ground speed of 2.4 mph and 30 psi. Treatments were applied on 27 Jul except for the simulated chemigation application of Dipel which was applied on 30 and 31 Jul. Treatments were interrupted on 27 Jul by 0.88 inch of rain immediately following the application of the simulated chemigation application of MVP. Another 0.44 inch of rain fell on the morning of 28 Jul. Comite was applied on 6 Aug to one set of plots to produce a mite free check. The purpose of a mite-free check is to reduce mite pressure in order to help evaluate the effect of mites on the corn border populations and corn yields. Corn borer counts were made between 29 Aug and 10 Sep by dissecting 15 corn plants from the center two rows in each plot. The number of larvae, the number of tunnels, and length of tunneling was recorded for each plant and the results were analyzed using SAS Proc ANOVA. Results are reported as the amount per 15 plants.