EVALUATION OF ENTRUST AGAINST WESTERN FLOWER THRIPS FOR ORGANICLETTUCE PRODUCTION, 2003

Abstract

The objective of the study was to evaluate the efficacy of Entrust insecticide against WFT when applied alone or and in combination with other bio-based insecticides used for organic lettuce production. Lettuce was direct seeded on 30 Sep at the Yuma Valley Agricultural Center, Yuma, AZ into double row beds on 42-inch centers. Stand establishment was achieved using overhead sprinkler irrigation, furrow irrigated thereafter. Plots were 2-beds wide by 35-ft long and bordered by two untreated beds. Four replications of each treatment were arranged in a RCB design. Formulations and rates for each compound are provided in the tables. Foliar applications were made with a CO2 operated boom sprayer operated at 60 psi and 20 gpa. A broadcast spray was delivered through two nozzles (TX-18) per bed. Sprays were applied on 29 Oct and 5 Nov. No adjuvants were added to the treatments. WFT populations were assessed by sampling plants and recording the numbers of adults and larvae from five plants per replicate on 31 Oct, 4, 7, 11 and 14 Nov. Relative WFT numbers were measured by randomly removing plants from each replicate 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 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 1-way ANOVA with means compared where appropriate using an F protected LSD (P ≤ 0.05).