Evaluation of Selected In-Furrow and Foliar Applied Insecticides for Control of Thrips on Cotton, 1997

Abstract

Abstract ‘Delta and Pine Land 51’ cotton was planted 1 May at the Virginia Tech Tidewater Agric. Res. & Ext. Ctr., Suffolk, VA using a 36-inch row spacing. In-furrow treatments (IF) were applied at the time of planting, granules using tractor-mounted inverted jars with lid holes calibrated to deliver exact amounts via gravity, liquids with a CO2-pressurized tractor-mounted sprayer calibrated to deliver 5.0 gpa at 24 psi through one SS8001E flat-fan nozzle mounted just above the planter disks and turned parallel to row direction to deliver the spray fan into the seed furrow. Gaucho 480 seed treatment was applied commercially. Foliar materials were applied in a 12-to 14-inch band over the row with a CO2-pressurized backpack sprayer calibrated to deliver 17.0 gpa at 22 psi through one 8004E flat-fan nozzle per row. A RCB design was used with 4 replicates; plots were 4 rows by 40 ft. Thrips injury to plants was rated visually on a 0 to 5 scale: 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. Flowers were counted on 23 and 30 Jul, and open bolls were counted on 15 and 22 Sep in the 2 center rows of each plot. Yield was determined by harvesting the 2 center rows of each plot (80 row-ft per plot) using a commercial 2-row John Deere cotton combine. Lint values were calculated as 37% of total plot weights, assum-ing 63% was seed and trash. Data were analyzed using ANOVA and LSD, or Duncan’s New Multiple Range statistical procedures.