EVALUATION OF FOLIAR INSECTICIDES FOR CONTROL OF CORN BORERS IN FIELD CORN, 2004

Abstract

The objective of the study was to determine the effectiveness of insecticides applied to corn foliage against corn borers. Field corn ‘Pioneer 3345’, a non-BT cultivar, was planted with a John Deere 7100 Maximerge planter at a rate of 2.2 seed per row ft. at the Cotton Branch Experimental Station, Mariana, AR on 16 Apr (early planting) and 1 May (late planting) 2004. Soil type was silt loam and had been planted to cotton in 2003. Plots consisted of one row 45 ft long. Plots were separated by 80 inches. Replications were separated by 5 ft bare ground buffers. The experimental design was RCB with four replications. Applications were timed by splitting corn stalks in adjacent plots and searching for corn borer pupae. A single insecticide application was made on 30 Jun, one week after the first dark pupae were detected. Insecticides were applied with a CO2 propelled backpack sprayer equipped with two Delvan HB10 nozzles. Spray volume was 14.8 gpa at 25 psi. Insecticide effectiveness was assessed as follows. On 24 Aug 10 randomly selected plants were cut at soil level from each plot. Each stalk was split with a band saw and corn borer damage was assessed for each stalk internodes. On each plant, damage to the first 15 internodes beginning at ground level and counting upward, was determined. Any stalk with a single damaged internode was considered infested. Stalks with more than 2 damaged internodes were categorized as having major damage. Ear damage was rated on a 0 to 5 scale, with 5 the most severe. Data were analyzed using ANOVA and means were separated using an F-protected LSD (P ≤ 0.05).