In-Whorl Treatments for Fall Armyworm and Second-Hrood European Corn Horer in Late-Planted Field Corn, 1987

Abstract

Abstract Corn was planted on 22 Jun and 2 Jul at the Highland Rim Experiment Station, Springfield, Tenn. Twelve and 20 treatments in the 1st and 2nd plantings, respectively, replicated 4 times were arranged in a randomized complete block design. Plots were 3 rows × 30 ft in the 1st planting and 4 rows × 30 ft in the second planting. Blocks were separated by 5-ft alleys, and rows were spaced 40 inches apart with 45 plants/30 row-ft. The middle row was evaluated for whorl damage and ensilage yield in the 1st planting, and the 2 middle rows in the 2nd planting were evaluated for whorl damage and stalk feeding. Liquid formulations were applied using 2.5-gal compressed-CO2 sprayers at 30 psi and 30 gal/acre. Granular insecticides were applied with shaker jars. In the 1st planting, 1 insecticide application was made on 28 Jul, when 57% of the plants were infested with an average of 1.9 larvae/plant. Ensilage yield was determined on 7 Oct at 46.3% moisture. In the 2nd planting, the 1st insecticide application was made on 3 Aug, when 78% of the plants were infested with an average of 2 larvae/plant; the 2nd application was made on 18 Aug. Whorls with new damage caused by the fall armyworm (FAW) were counted 14 days after each application. European corn borer (ECB) stalk feeding counts (average number of basal tunnels/45 stalks) were made on 7 Oct at harvest. Soil type was Dixon silt loam, 2-5% slope. Total rainfall for the growing season was 8.64 inches.