Foliar Sprays to Control Lepidopteran Larvae on Late-Planted Sweet Corn, 1983

Abstract

Abstract ‘Silver Queen’ sweet corn was planted 14 July to a Sassafras sandy loam field. Plots were four rows wide on 30-in. centers and 25 ft long. Whorl sprays were applied with a tractor-mounted boom sprayer with one nozzle centered over the row calibrated to deliver 55 gal/acre at 200 lb/in2; foliar sprays at silking were applied with a self-propelled, high-clearance sprayer with four nozzles per row, directed at the ear zone, which delivered 220 gal/acre at 200 lb/in2. Whorl treatments were applied 23 and 31 Aug. Foliar sprays at silking were applied 16, 19, and 29 Sept. Twenty plants from the middle two rows were evaluated on 6 Sept. for armyworm damage. The categories for armyworm foliar feeding damage are as follows: 0, no damage; 1, slight damage; 2, 10% damage; 3, moderate damage, 25% of whorl destroyed; 4, heavy damage, 50% of whorl destroyed; and 5, severe damage, skeletonized, whorls destroyed. At harvest (1 Oct.) 20 ears from the middle two rows of each plot were evaluated for ‘worm’ damage as “none” (clean-no damage), “tip” (less than 1.5-in. tip damage) and “side” (culls). On 10 Oct., 20 stalks from the middle two rows of each plot were split from tassel to soil surface; each inch of European corn borer damage was recorded as one cavity.