Boll Weevil Control with Insecticide Applied in Sprays with Narrow-Spectrum Droplet Sizes123

Abstract

Results of tests initiated in 1967 to determine the effect of size of spray droplets on boll weevil control showed that adequate control could be obtained with 0.125 Ib per acre of azinphosmethyl applied in ultra-low-volume (ULV) sprays with droplet sizes of 140, 200, or 300 µ at 4- to 5-day intervals. The treatments were as effective as a wide spectrum of droplet sizes applied with a spinning-disc sprayer. Azinphosmethyl applied at 0.0625 lb per acre on a 4- to 5-day schedule in a ULV spray in droplet sizes of 100 and 140 µ was as effective as when it was applied in a wide spectrum of droplet sizes at 0.125 or 0.0625 lb/acre. Sprays with droplet sizes of 200µ gave marginal control when used to apply azinphosmethyl in a ULV spray at 0.0625 lb/acre on a 4- to 5-4day schedule and control with 300 µ droplets under the same conditions was inadequate.