COMPARISON OF SUCCESS TREATMENTS FOR CONTROL OF WESTERN FLOWER THRIPS ON ROMAINE, SPRING, 2003

Lettuce was direct seeded on 12 Dec at the Yuma Valley Agricultural Center, Yuma, AZ into double-row beds on 42-inch centers. Stand establishment was achieved using overhead sprinkler irrigation, and irrigated with furrow irrigation thereafter. Plots were two-beds wide by 50-ft long and bordered by two untreated beds. Four replications of each treatment were arranged in a RCB design. Foliar applications were made with a CO2 operated boom sprayer operated at 60 psi and 27 gpa. A directed spray (nozzles directed toward the plants) was delivered through three nozzles (TX-12) per bed. A total of two spray applications were applied on 22 Jan and 8 Feb. An adjuvant DyneAmic, was applied at 0.125% v/v to all foliar treatments. Numbers of WFT from five randomly selected plants per replicate were recorded on each sample date. Relative WFT numbers were measured by removing plants and beating them vigorously against a screened pan for a predetermined time (15 sec). A 6 × 6-inch sticky trap was placed inside of the pan to catch the dislodged WFT. Sticky traps were then taken to the laboratory where adult and larvae were counted. WFT counts were transformed (log10 n + 1) before analysis of variance to stabilize variances that were found to be heterogeneous. Untransformed means are presented in tables. Data were analyzed as a 1-way ANOVA with means compared where appropriate using a protected LSD (P = 0.05).