Integrating cover crops and targeted herbicide applications in cotton production

Abstract

Cover crops are part of integrated weed control management to help mitigate herbicide resistance evolution. Targeted sprays from the John Deere See & Spray are currently not recommended in cover crops. Experiments were conducted yearly from 2022 to 2024 in Keiser, AR, to evaluate targeted applications (TAs) with cover crops in cotton (Gossypium hirsutum L.). Treatments assessed the main effect of winter cover crop (fallow, cereal rye [Secale cereale L.], or hairy vetch [Vicia villosa Roth]), herbicide application methods (nontreated, broadcast [BC], TA + BC residuals [TA + BCRs], or TA only), and the interaction on cotton tolerance, weed control, and herbicide savings. Cereal rye generally aided weed control efforts across the weeds evaluated, and there were instances of herbicide savings at the preemergence and mid-postemergence (MPOST) timings when using TA or TA + BCR relative to BC. In some instances, TA POST + RES reduced weed control. At layby, TA-only applications reduced Palmer amaranth control by 5–10 percentage points in winter fallow systems compared to the BC in 2022 and 2023. In 2024 at MPOST, low herbicide savings occurred in the winter fallow cover systems (2.9%), whereas TA + BCR saved 29.4% and 26.5% for cereal rye and hairy vetch, respectively. In conclusion, See & Spray improved environmental stewardship and could detect and treat weeds in standing cover crop biomass, providing comparable control to the BC application at the end of the season (≥92% for all species).