Supplemental Control with Diamides for Heliothines in Bt Cotton

Abstract

Abstract. Supplemental control with diamides for bollworm, Helicoverpa zea (Boddie), in Bt cotton is becoming more frequent, but there is little information on net returns to growers. The value of spraying Bt cotton with commercially available diamides was evaluated at seven locations in the Mississippi Delta cropping region in 2014 and 2015. Plots of Bollgard II®, Widestrike 3®, and non-Bt cotton varieties planted at each location were divided into five subplots. Treatments randomly assigned to subplots of each cotton cultivar were: 1) lowest labeled rate of chlorantraniliprole applied at threshold, 2) lowest labeled rate of flubendiamide applied at threshold, 3) lowest labeled rate of λ-cyhalothrin + chlorantraniliprole applied at threshold, 4) sprayed check, which was the maximum labeled rate of chlorantraniliprole applied on a 3-week schedule and initiated before first bloom to minimize damage from heliothines, and 5) nontreated check. Each plot was monitored weekly for larval abundance and plant dama...