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Agricultural industry

Cover Crops Show Promise in Suppressing Herbicide-Resistant Weeds

Strategic Insights

— 2 min read

Researchers at Kansas State University and Cornell University have conducted a study on the effectiveness of cover crops in suppressing herbicide-resistant weeds in the semiarid Central Great Plains. The study, which was conducted from 2021 to 2024, involved planting a mixture of oats, barley, and spring peas as cover crops in no-till sorghum stubbles and terminating them at the oats heading stage. The results showed that the cover crops reduced total weed density by 78% to 99% and total weed biomass by 93% to 99% compared to weedy fallow. The study also found that the combination of cover crops and residual herbicide continued to suppress weeds for at least 90 days and did not affect subsequent wheat grain yield.

Key Takeaways:

  • The study found that cover crops can reduce total weed density by 78% to 99% and total weed biomass by 93% to 99% compared to weedy fallow.
  • The combination of cover crops and residual herbicide can continue to suppress weeds for at least 90 days.
  • The study did not find any significant difference in wheat grain yield between cover crop treatments and chemical fallow in certain years, but found that chemical fallow and cover crops terminated with glyphosate + flumioxazin/pyroxasulfone had greater wheat yield than cover crops terminated with glyphosate only in one year.
  • The research suggests that integration of spring-planted cover crops with residual herbicide may help suppress glyphosate-resistant kochia and Palmer amaranth in the semiarid Central Great Plains.
  • The study was conducted from 2021 to 2024 and was supported by the NC SARE Graduate Student Grant.
  • The research was peer-reviewed and published in the journal Weed Science.

Statistics:

  • Total weed density reduction by cover crops: 78% to 99%
  • Total weed biomass reduction by cover crops: 93% to 99%
  • Weed suppression by combination of cover crops and residual herbicide: 52% to 80% (total weed density) and 70% (total weed biomass)
  • Wheat grain yield difference between cover crop treatments and chemical fallow: not significant in 2021-2022 and 2022-2023, but significant in 2023-2024

Sources:

  • Combined Effects of Spring-planted Cover Crops and Residual Herbicide On Weed Suppression and Subsequent Wheat Yield In the Semiarid Central Great Plains. Weed Science, 2025;73(1). Cambridge Univ Press, Edinburgh Bldg, Shaftesbury Rd, CB2 8RU Cambridge, England.
  • NewsRx. New Findings on Cover Crops from Cornell University Summarized (Combined Effects of Spring-planted Cover Crops and Residual Herbicide On Weed Suppression and Subsequent Wheat Yield In the Semiarid Central Great Plains). Agriculture Week. August 14, 2025; p 1758.

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