Evaluation of PRE Herbicides and Seed Treatment on Thrips Infestation and Cotton Growth, Development, and Yield

Abstract

The use of preemergence (PRE) herbicides may result in decreased early season cotton (Gossypium hirsutum L.) growth, which may exacerbate injury from thrips. Studies were conducted in 2013 and 2014 at the Black Belt Branch Experiment Station near Brooksville, MS; at the R.R. Foil Plant Science Research Center near Starkville, MS; and at the Delta Research and Extension Center in Stoneville, MS, to evaluate the impact of PRE herbicides and insecticide seed treatments on thrips infestations in cotton. DP 0912 B2RF was treated with thiamethoxam + fungicide, imidacloprid + fungicide, and fungicide only. All cotton seed, including the fungicide‐only treatment, were base treated with metalaxyl, pyraclostrobin, and fluxapyroxad. Preemergence herbicides included fluometuron at 1.12 kg a.i. ha−1, diuron at 1.12 kg a.i. ha−1, fomesafen at 0.28 kg a.i. ha−1, S‐metolachlor at 1.07 kg a.i. ha−1, and S‐metolachlor at 1.07 kg a.i. ha−1 + fluometuron at 1.12 kg a.i. ha−1. An untreated check was included for comparison purposes. Cotton injury from thrips was less prevalent on cotton grown from seed treated with imidacloprid. Immature thrips counts at the 4‐leaf cotton growth stage were greatest on cotton grown from seed treated with thiamethoxam, which had 136 thrips per five plants. Preemergence herbicides did not impact thrips infestations at the 2‐ or 4‐leaf cotton growth stage. No significant differences in cotton lint yield were observed due to PRE herbicide application. Seed treatments that included imidacloprid resulted in 80 kg ha−1 more lint than cotton grown from seed treated with thiamethoxam.Core Ideas Cotton seed treated with imidacloprid resulted in greater cotton yields compared with cotton grown from seed treated with thiamethoxam. Preemergence herbicide application had no impact on cotton yield. Based on these data, growers are encouraged to utilize a preemerence herbicide of their choice to manage Palmer amaranth, and imidacloprid‐based seed treatments are recommended.