Evaluation of Imidacloprid for Control of Sweetpotato Whitefly in Lettuce, 1994

Lettuce was direct seeded into double-row beds on 1 Sep and immediately irrigated with overhead sprinklers at the Yuma Valley Agricultural Center, Yuma, AZ. Plots consisted of four, 75 ft long beds spaced 42 inches apart and bordered on each side by two unplanted beds. Plots were arranged in a completely randomized block design with 4 replicates. The Admire 2F treatments placed below the surface at 1.5 and 3.0 inches were applied by injecting the material into the beds with long, narrow shanks before seeding. The Admire surface band application was applied as a 2 inch band using 8003 flat-fan nozzles centered on the seedline immediately following planting and preceding irrigation. All Admire treatments were applied with water and delivered at 20 gal/acre total volume. Foliar treatments of Admire 2F and Capture + Thiodan were applied on 15, 20, 28 Sep and 6, 13, 18 Oct with a CO2-powered backpack sprayer with a two-bed boom, having two nozzles per bed (TX 12 hollow cone), and delivering 20.5 gal/acre at 40 psi. SPWF densities were estimated by counting the number of eggs and nymphs on two-cm2 disk sections from each of 20 leaves per plot on 22 Sep, 17 Oct, and 10 Nov. All heads in a single, randomly selected 20 ft section per plot were harvested on 11 Nov and evaluated for head weight and size. Because of heterogeneity of mean variances, insect data was transformed (logl0 x + 1) prior to analysis. Treatment differences among means were estimated with a protected LSD0.05.