Persistence of Dipel Es, 1994

Dipel ES was evaluated for persistence and efficacy against tobacco budworm in a field of Deltapine 51 cotton planted at the Macon Ridge Branch of the Northeast Research Station near Winnsboro, LA on 18 Apr. Plots consisted of two rows of cotton plants (40 inch centers) by 50 ft. Treatments were arranged in a RCB design with 4 replications. Insecticide treatments (untreated, Dipel ES at 4.0 and 16 oz (form)/acre) were evaluated at 3 time intervals after treatment (2, 24 and 48 h). Insecticides were applied on 6 Jun with a tractor mounted spray boom equipped with a compressed air delivery system calibrated to deliver 10 GPA at 42 psi through two 8001 fiat fan nozzles equally spaced per row. No rainfall occurred during this study. At 2, 24 and 48 h after insecticide application (HAT), 25 cotton plant terminals were randomly collected from each plot and placed in florist water pics. Two 2nd instar LSU-LAB tobacco budworm larvae (S4 days old; 3.3-7.7 mg) were placed on each plant terminal. Larvae were confined to plant terminals for 72 h after which mortality was recorded. A larva was considered dead if it was unable to right itself within 15 s after being prodded. Mortality was corrected for that observed on untreated plant terminals using Abbott’s formula. All data were subjected to ANOVA and means were compared using Least Significant Differences.