EVALUATION OF SELECTED IN-FURROW AND SEED APPLIED INSECTICIDES, WITH AND WITHOUT AN ADDITIONAL FOLIAR BROADCAST APPLICATION AT COYTLEDON OR FIRST TRUE LEAF STAGE, FOR CONTROL OF THRIPS, 2004

Abstract

Selected insecticides applied onto seed or into the seed furrow at planting, both with and without an additional broadcast treatment at cotyledon (BC at cotyl) or first true leaf stage (BC at 1 tl), were evaluated for control of thrips in cotton. ‘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. Cruiser 5FS and Gaucho 480 seed treatments were 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 11 May at the cotyledon stage or on 17 May at the first sign of true leaf emergence after the cotyledon 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 (41% lint, 59% seed and trash). Data were analyzed using ANOVA and means were separated using LSD (P ≤ 0.10).