INFLUENCE OF SPRAY ADJUVANTS ON THE EFFICACY OF SUCCESS AGAINST WESTERN FLOWER THRIPS, SPRING 2002

Abstract

The objective of the study was to compare the efficacy of Success against western flower thrips (WFT) when applied alone and in combination with several spray adjuvants. 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 randomized complete block design. Formulations and rates for each compound are provided in the tables. Foliar applications were made with a CO2 operated boom sprayer at 40 psi and 26.5 gpa. A directed spray (~75% band, with rate adjusted for band) was delivered through three nozzles (TX-18) per bed. Sprays were applied on 7 and 19 Feb, and 5 Mar. Numbers of thrips adults and larvae from 5-8 plants per replicate were recorded on each sample date. Relative thrip numbers were measured by removing plants and beating them vigorously against a screened pan for a predetermined time. A 6 inch by 6 inch sticky trap was placed inside of the pan to catch the dislodged thrips. Sticky traps were then taken to the laboratory, where adults and larvae were counted under magnification. WFT counts were transformed (log10 n+1) before ANOVA to stabilize variances that were found to be heterogeneous. Untransformed means are presented in tables. Data were analyzed as a one-way ANOVA with means compared where appropriate using a protected LSD F-test(P < 0.05).