Control of Corn Earworm on Sweet Corn, 1991

Abstract

On 11 Apr, Florida Stay Sweet' sweet corn was seeded into fine, sandy loam soil at the Wes Watkins A.R.E.C., Lane, OK. Plots were 12 ft long and 4 rows wide with 3 ft spacing between rows and 4-6 inch spacing between plants. Plot buffers were 8 ft long with two unplanted rows between plots. Plots were arranged in a randomized complete block design with four replications. Fertilizer and herbicides were applied at recommended rates. Overhead irrigation was initially used to establish plant stand, but was later replaced with a trickle irrigation system. All insecticide applications were made with a tractor-mounted PTO-driven air pressure sprayer calibrated at 35.0 gallons per acre. Three TX-18 spray nozzles per row were suspended from the boom with two nozzles at the level of the silks and one nozzle above the row. A single broadcast application of Javelin WG at 0.5 lbs per acre was made on 7 Jun to control larvae in the whorls. Eight insecticide applications were made on a two-day schedule on the following dates: 13, 15, 17, 19, 21, 24, 26, and 28 Jun. Plots were harvested on 1 Jul. Each ear was evaluated for CEW damage and categorized as undamaged, marketable, or unmarketable. Marketability was determined by measuring the depth of CEW penetration from the tip. Ears less than five inches in length after trimming all CEW damage from them were considered unmarketable. Each ear was also evaluated for pollination and categorized as complete (100% filled kernels), marketable (80-90% filled kernels), and unmarketable (less than 80% filled kernels).