Evaluation of Insecticides for Control of Lepidoterous Larvae in Lettuce, 1992

Lettuce was direct seeded into double-row beds on 17 Sep at the Yuma Valley Agricultural Center, Yuma, AZ. The plots were not thinned prior to the experiment. Each plot consisted of three, 50 ft long beds spaced 42 inches apart and bordered on each side by an untreated bed. Plots were arranged in a completely randomized block design with 4 replicates. Foliar treatments were applied on 8, 13, and 19 Oct with a tractor-mounted boom sprayer (2 TX-8 nozzles/row) operated at 40 psi, delivering 25 gal/acre. Spreader-sticker (Dynamic) was included in all spray treatments at a rate of 0.5% of the total volume. Insecticide efficacy was determined by counting the total number of small (1st and 2nd instars) and large (> 2nd instar) BAW and CL larvae on 25 randomly selected lettuce plants per replicate. Insect counts were conducted on 7, 13, 19, and 25 Oct. Data were analyzed for treatment differences using ANOVA and a protected LSD.