EVALUATION OF DPX-E2Y45 FOR CONTROL OF LEPIDOPTEROUS LARVAE ON FALL LETTUCE, 2004

Abstract

The objective of the study was to evaluate the efficacy of the new compound DPX-E2Y45 relative to standard materials used against lepidopterous larvae on head lettuce under desert growing conditions. Lettuce was direct seeded on 26 Aug 2004 at the Yuma Valley Agricultural Center, Yuma, AZ into double-row beds on 42-inch centers. Stand establishment was achieved using overhead sprinkler irrigation, with furrow irrigation used thereafter. Plots were two beds wide by 40-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. Sprays were applied on 9 Sep, 16 Sep, 24 Sep and 1 Oct. A rotation treatment was included that consisted of alternating compounds in the following manner: first spray was Lannate (0.75 lb product/acre) + Renounce (3 fl oz product/acre); second spray was Lannate (0.5 lb product/acre) + Orthene (1.0 lb product/acre); third spray was Intrepid (8 fl oz product/acre); and the fourth spray was Proclaim (3.2 oz product/acre). The applications were made with a CO2-operated boom sprayer at 60 psi and 21.5 gpa. A broadcast application was delivered through two TX-18 ConeJet nozzles per bed. An adjuvant, DyneAmic, was applied at 0.125% v/v with all but the DPX-E2Y45 treatments. Evaluation of efficacy was based on the number of live larvae per plant. Ten plants per replicate were destructively sampled on each sample date. The sample unit consisted of examination of whole plants for presence of small and large BAW and CL. For BAW, larvae were considered small if 5mm in length. For CL, larvae were considered small if 10 mm. Treatment means were analyzed using a 1-way ANOVA and means separated by a protected LSD (P = 0.05).