Corn Earworm Control on Sweet Corn, 1992

‘Maple Sweet’ cv. sweet corn was seeded on 15 May at the Wes Watkins A.R.E.C, Lane, OK. Plots 5.8 m long by 4 rows wide were arranged in a randomized complete block design with four replications. Rows were spaced 91 cm apart and plants were spaced 10-15 cm apart within rows. Two unplanted rows between plots and 1.5 m within rows served as spray buffers. Standard cultural practices were used throughout the trial. Treatments were applied with a tractor mounted PTO-driven air pressure sprayer calibrated at 95.8 liters per acre. Six insecticide applications were made on a 3 x per week regime on the following dates: 9, 13, 15, 17, 20 and 22 Jul. Three TX-10 spray nozzles per row were suspended from the boom with one nozzle on each side of the row directed inward at the level of the silks and one nozzle above the row. Thirty primary ears from each plot were harvested on 24 Jul and evaluated for CEW damage. Each ear was categorized according to USDA standards as undamaged, marketable or unmarketable. Marketability was determined by measuring the depth of CEW penetration from the tip of the ear. Ears with no damage beyond 38 mm from the tip or at least 12.7 cm in length after trimming all damage from them were considered marketable. Ears were considered unmarketable if damage extended beyond 38 mm from the tip or if total undamaged length was less than 12.7 cm after trimming. Average penetration depth was also calculated.