Evaluation of Selected Seed, In-Furrow Liquid At-Planting, and Foliar Insecticides for Control of Thrips in Cotton, 2014 * Open Access

Selected seed-applied, in-furrow liquid at-planting, and foliar broadcast insecticides were evaluated for control of thrips in cotton. ‘DP 1028 B2RF’ cotton was planted 5 May at the Virginia Tech Tidewater Agric. Res. & Ext. Ctr., Suffolk, VA, using 36-inch row spacing. Liquid in-furrow treatments (Belay and Orthene) were applied into the seed furrow at 5 gpa using a microtube mounted between the disc openers, pressurized by CO ₂ at 51 psi. The foliar applications (Orthene and Knack) were broadcast at the first true leaf stage on 19 May with a CO ₂ -pressurized backpack sprayer calibrated to deliver 14.3 gpa at 18 psi through 8004VS nozzles spaced 18 inches apart on the spray boom. A RCB design was used with 4 replicates; plots were 4 rows by 40 ft. Thrips injury to plants was determined on four dates by visually rating injury using a 0–5 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 >25% buds injured; and 5 = dead plants. Yield was determined by harvesting two rows of each plot (end-trimmed to 64 row ft) using a commercial two-row cotton picker. Sub-samples were ginned to determine lint versus seed and trash weight (46.3% lint, 53.7% seed and trash). Data were analyzed using ANOVA and LSD statistical procedures.

There were differences in thrips injury ratings between treatments on each sample date ( Table 1 ). Injury ratings were significantly lower in treated plots compared to untreated check plots on each date. The plots using Aeris-treated seed along with Belay (at 6.4 oz/acre) did not have the lowest thrips injury rating on any date sampled, but did have the highest yield at the end of the season. There was no significant difference in yield between any treatments, including treatments using Knack, an insect growth regulator, and treatments that consisted only of Aeris-treated seed.

Author notes