EVALUATION OF AN IN-FURROW AND SEED APPLIED INSECTICIDES, WITH AND WITHOUT ADDITIONAL BROADCAST APPLICATION FOR CONTROL OF THRIPS, 2004A

Abstract

Selected insecticides applied onto seed or into the seed furrow at planting, both with and without an additional broadcast treatment at first true leaf stage (BC at 1 tl), and an insecticide with broadcast applications at both first true leaf and 2-3 leaf stages (BC at 2-3 leaf), were evaluated for control of thrips. ‘Delta Pine 432 RR’ cotton was planted 28 Apr at the Virginia Tech Tidewater Agric. Res. & Ext. Ctr., Suffolk, VA, using 36-inch row spacing. In-furrow (IF) treatments were applied into the seed furrow at the time of planting using tractor-mounted inverted jars with lid holes calibrated to deliver exact amounts via gravity. Gaucho 480 seed treatment was applied commercially. The foliar treatments were applied with a CO2 pressurized backpack sprayer as a broadcast at 14.3 gpa and 18 psi through 8002VS nozzles spaced 18 inches apart on the spray boom. Foliar applications were made on 17 May at the first sign of true leaf emergence after the cotyledon stage and on 24 May at the 2-3 leaf stage. A RCB design was used with 4 replicates; plots were 4 rows by 40 ft. Thrips injury to plants was determined by visually rating injury using a 0 to 5 scale, where 0 = no thrips induced plant injury, 1 = 10% injured leaves, no bud injury; 2 = 25% injured leaves, no bud injury; 3 = 75% injured leaves, and 0 to 25% buds injured; 4 = 90% injured leaves, and greater than 25% buds injured; and 5 = dead plants. Yield was determined by harvesting the 2 center rows of each plot (80 row ft) using a commercial 2-row John Deere cotton picker. Sub-samples were ginned to determine lint versus seed and trash weight (40% lint, 60% seed and trash). Data were analyzed using ANOVA and means were separated with LSD (P ≤ 0.10).