Control of Corn Earworm on Sweet Corn, 1990

Abstract

Abstract On 19 Jun 1990, 'Florida Stay Sweet' sweet corn was seeded into fine, sandy loam soil at the Wes Watkins AREC, Lane, OK. Plots were 12 ft long and 4 rows wide with 3 ft spacing between rows and 6 in between plants. Plot buffers were 10 ft long and 2 unplanted rows were left between plots. A randomized complete block design was used with four replications. Fertilizer was applied according to soil test recommendations. Overhead irrigation was used to establish the plant stand initially, but was later replaced with trickle irrigation. Treatments with 2-day application schedules were sprayed on six dates: 9, 11, 13, 15, 17 and 20 Aug. Insecticide application on plots with 4-day application schedules had three applications made on 9, 13 and 17 Aug. Treatments were made using a tractor-mounted PTO-driven air pressure sprayer which delivered 16.7 gal/acre at 40 psi. Two TX-10 spray nozzles per row were suspended from the boom at the level of silks on both sides of plant. Harvests were made on 17 and 21 Aug. Each ear was evaluated for CEW damage by rating the tip (proximal 3.8 cm) and ear (excluding tip area) using a scale of 1-5 where 1 = no damage, 2 = slight damage (<20%), 3 = moderate damage (20-50%), 4 = heavy damage (50-75%) and 5 = severe damage (>75%). A rating system of 1- 5 was used to evaluate the degree of pollination on each ear, where 1 = complete pollination (100% full kernals) to 5 = no pollination. The percentage of ears with no damage was also calculated from these ratings.