Threshold Control of Armyworm on No-Till Field Corn, 1992

Abstract

Abstract An experiment was conducted in 1992 in Pulaski County, VA, to determine the effectiveness of Asana XL and 2 formulations of Lorsban (4 E and 4 E-HF) against amryworm in field corn. Plots were established in a 7 acre field. The recent cropping history for this field included field corn planted in 1990 and 1991 followed by a cover crop of barley each year. Corn rows were spaced at 30 inches. The field was being scouted every 5 to 6 d for armyworm. On 16 Jun armyworm levels in the field approached the established economic threshold. Armyworms were early 5th instar and corn was at the 6 to 8 leaf stage. The experimental design was a randomized complete block with 4 replications. Each plot was 4 rows wide by 50 ft. Treatments were applied on 18 Jun. Just before and 7 d after treatments were applied, armyworms were counted on 25 corn plants in the middle 2 rows of each plot. A backpack sprayer, fitted with stainless steel 8002VS spray tips, was used to broadcast the insecticides approximately 18 inches above the corn canopy. The sprayer was calibrated to deliver a rate of 20 gal/acre at 40 psi. Approximately 0.1 to 0.2 inches of rain fell on the plots shortly after the Lorsban treatments were applied. Data analysis were done using SAS.