Evaluation of Conventional Insecticides for Western Flower Thrips Control in Lettuce, 1997

A field trial was conducted at the University of Arizona Yuma Agricultural Center. Lettuce was direct seeded Dec 2 into double-row beds on 42-inch centers. Plots consisted of 4 beds, 60 feet long with a two-bed buffer between the plots. Plots were arranged in a RCB design with four replications. The foliar treatments were applied in 40 gpa total volume at 160 psi. A spreader/sticker was used with all treatments (Latron at 0.25% v/v). Three disc-type cone nozzles were used per bed. Two applications were made in each trial; 12 and 24 Feb. Evaluations of thrips control were based on the number of live adults and nymphs per plant sampled from the center 2 rows of each replicate on 11, 18 Feb, and 2 Mar. Numbers of thrips from 5 plants per replicate were recorded on each sample. Samples were taken by removing plants and beating them vigorously against a screened pan. Inside of the pan was a sticky trap to catch the dislodged thrips. Sticky traps were then taken to the laboratory where adult and immature thrips were identified to species and counted. Data were analyzed as a one-way ANOVA using a protected LSD F test to distinguish treatment mean differences.