Binary Mixtures of Selected Insecticides for Control of Heliothis Spp. in Cotton, 1987

Abstract

Abstract A small-plot field study was conducted at the Texas A&M University Research and Extension Center at Corpus Christi to evaluate several insecticides (applied singly and in binary mixtures) for control of Heliothis spp. in dryland cotton. Nine treatments and an untreated check were compared in 3-row × 30-ft plots of cotton planted 16 Apr on 38-inch rows. Treatments and the untreated check were replicated 4 times in a randomized complete block design. The first application of treatments occurred 3 wk past first-bloom-stage of cotton growth on 24 Jun; treatments were applied again on 30 Jun. One day prior to the first application of treatments, random inspection of plants showed that the test site was infested with 48 Heliothis eggs and 5 small Heliothis larvae/100 plant terminals; there were no Heliothis damaged squares (n = 100 squares). Also, identification of Heliothis larvae (n = 25) collected from the test site one day prior to the first application of treatments indicated that the infestation consisted of 65% H. virescens and 35% H. zea. Treatments were applied with a CO2-pressurized (35 psi) backpack sprayer, calibrated to deliver 4.5 gal total spray/acre through 2 size 3X hollow-cone nozzles/row. After each application, efficacy of each treatment was evaluated by inspecting the terminals of 20 randomly chosen plants in each plot for presence of Heliothis feeding damage and numbers of larvae and by inspecting 20 randomly chosen squares and bolls in each plot for presence of Heliothis feeding damage and numbers of larvae. Seed cotton was hand harvested from a 13.6-ft section of row in each plot for yield analysis.