Whorl Applications to Control Fall Armyworm in Corn, 1986

Abstract

Abstract Silver Treat’ sweet com were planted 10 Jul into a Sassafras sandy loam field. Plots were 4 rows wide on 30-inch centers and 25-ft long. Treatments were replicated 4 times in a randomized complete block design. Granular whorl treatments were applied with a hand shaker in a 7-inch band over the whorl; whorl sprays were applied with a self-propelled, high-clearance ·prayer with one nozzle centered over each of the middle 2 rows calibrated to deliver 24 gal/acre at 40 psi operated at 2 mph. All treatments were applied on 18 Aug. Twenty plant whorls were rated for fall armyworm damage on 22 Aug as follows: (0) no damage; (1) slight damage, up to 10% whorl feeding; (2) moderate damage, 10-25% whorl feeding; (3) heavy damage, 25-50% feeding damage; (4) severe damage, 50-75% whorl feeding, tassel damaged; and (5) whorl destroyed. Twenty whorls were removed from the plants, unrolled, and all live armyworm larvae were counted. On 29 Sep, 20 ears were harvested, weighed, and rated for ‘worm’ damage as follows: (1) clean ear, no damage; (2) tip-damage, less than 3.6 cm of visible damage from the tip; and (3) culls (damage greater than 3.6 cm from the tip or damage to the side and/or bottom of the ear).