Integration of cover crops and herbicides for weed control in cotton

Authors: KUMARI, ANNU - Auburn University; Price, Andrew; GAMBLE, AUDREY - Auburn University; LI, STEVE - Auburn University

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/10/2023
Publication Date: 1/30/2023
Citation: Kumari, A., Price, A.J., Gamble, A., Li, S. 2023. Integration of cover crops and herbicides for weed control in cotton [ABSTRACT]. National Cotton Council Beltwide Cotton Conference.

Interpretive Summary: An experiment was conducted with the objective of increasing the adoption of integrated weed management tactics by combining weed-suppressive cover crop qualities and chemical weed control to maintain long-term viability for sustainable agriculture. Six cover crop systems were utilized as main plots in a split-plot design: winter fallow, cereal rye, black oats, crimson clover, radish, and a mixture. In addition, four herbicide treatments were used in subplots: no herbicide, a combination of two preemergence herbicides (Prowl H2O + Reflex), a combination of two postemergence herbicides (Liberty + Dual Magnum), and pre followed by postemergence herbicides. Results showed that the rye, clover, mixture, and oats with pre, post, or both treatments have significantly higher relative weed biomass reduction (>92%) than fallow pre, post, or both treatments (<80%). Cover crops with herbicides have significantly higher relative weed biomass reduction than fallow with herbicides. Additionally, pre + postemergence herbicides were most effective in weed control, and their effect remained late season. Among non-treated check of cover crops, rye has significantly higher weed biomass reduction than radish. In conclusion, cover crops, along with the inclusion of both preemergence and postemergence herbicides, suppressed weed density in cotton and significantly higher relative weed biomass reduction than non-treated checks.

Technical Abstract: In the southeastern United States, Palmer amaranth (Amaranthus palmeri S. Wats), morning glories (Ipomoea spp.), nutsedges (Cyperus spp.), sicklepod (Senna obtusifolia L.), prickly sida (Sida spinosa L.) and large crabgrass (Digitaria sanguinalis L. Scop.) are the major weed species threatening crop production systems. However, cotton grows comparatively slower than other row crops in germination and root development during the initial vegetative stage. Therefore, it is essential to keep cotton weed-free during the critical phase to maintain lint yield. An experiment was conducted with the objective of increasing the adoption of integrated weed management tactics by combining weed-suppressive cover crop qualities and chemical weed control to maintain long-term viability for sustainable agriculture. Six cover crop systems were utilized as main plots in a split-plot design: winter fallow, cereal rye, black oats, crimson clover, radish, and a mixture. In addition, four herbicide treatments were used in subplots: no herbicide, a combination of two preemergence herbicides (Prowl H2O + Reflex), a combination of two postemergence herbicides (Liberty + Dual Magnum), and pre followed by postemergence herbicides. Results showed that the rye, clover, mixture, and oats with pre, post, or both treatments have significantly higher relative weed biomass reduction (>92%) than fallow pre, post, or both treatments (<80%). Cover crops with herbicides have significantly higher relative weed biomass reduction than fallow with herbicides. Additionally, pre + postemergence herbicides were most effective in weed control, and their effect remained late season. Among non-treated check of cover crops, rye has significantly higher weed biomass reduction than radish. In conclusion, cover crops, along with the inclusion of both preemergence and postemergence herbicides, suppressed weed density in cotton and significantly higher relative weed biomass reduction than non-treated checks.