EVALUATION OF SELECTED SEED TREATMENTS AND IN-FURROW INSECTICIDES, WITH AND WITHOUT AN ADDITIONAL FOLIAR BROADCAST APPLICATION AT FIRST TRUE LEAF STAGE, FOR CONTROL OF THRIPS IN VIRGINIA COTTON, 2005

Abstract

Selected insecticides applied onto seed or into the seed furrow at planting were evaluated for control of thrips in Virginia cotton. 'Delta Pine 444 BG/RR' cotton was planted 3 May at the Virginia Tech Tidewater Agric. Res. & Ext. Ctr., Suffolk, VA, using 36-inch row spacing. Avicta 500FS, Cruiser 5FS, and Gaucho Grande seed treatments were applied commercially. 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. 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 broadcast on 23 May at the first sign of true leaf emergence after the cotyledon stage (BC at first true leaf). A RCB experimental design was used with four replicates; plots were four 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 cotton picker. Sub-samples were ginned to determine lint versus seed and trash weight (43% lint, 57% seed and trash). Data were subjected to ANOVA and means were separated using LSD (P = 0.01).