Control of Heliothis Species, 1986

Abstract

Abstract The relative efficacy of 6 Bacillus thuringiensis strains against Heliothis spp. was evaluated at the Macon Ridge Branch of the Northeast Research Station, Winnsboro, La., in a randomized complete block design with 5 replicates. Plots were 6 rows (40-inch spacing) by 100 ft. Cotton was planted 30 Apr on a loessial silt loam soil (Jigger-Gilbert complex) and fertilized with 70 lb nitrogen/acre. Temik (0.5 lb [AI]/acre) and Terraclor Super X (Terraclor 1.0 lb + Terrazole 0.25 lb [AI]/acre) were applied in furrow behind the planter. B. thuringiensis strains supplied by Ecogen, were applied with a high-clearance sprayer equipped with a compressed-air system for spraying small plots and delivering 10 gal/acre. Applications were made 10, 15, 22, and 29 Jul and 5, 12, 19, and 28 Aug. Methyl parathion (0.25 lb [AI]/acre) was applied on 17 Jun, 26 Jun, 1 Jul, and 6, 12, 15, and 19 Aug for boll weevils. The cotton was irrigated during droughty periods. The effects of the B. thuringiensis strains on Heliothis spp. were measured by observations of cotton terminals, squares, blooms, and bolls on the 2 center rows of each plot. Yields were determined by picking the 2 center rows of each plot (converted to lb seed cotton/acre) with a mechanical harvester 25 Sep and 16 Oct.