Abstract Cover crops have been progressively adopted by growers as a sustainable approach to control problematic and herbicide-resistant weeds. Understanding the critical period of crop-weed competition is essential for timely and effective weed management tactics in cropping systems. The two-year field experiment was conducted in Alabama to evaluate the effect of a cover crop mixture that included cereal rye, crimson clover, and hairy vetch, and solo cereal rye on the critical period for weed control (CPWC) in soybean. The experiment was implemented in a split-plot design in which the main plots were cover crop mixture, cereal rye, and winter fallow, and subplots were five durations of weed-free and weed-interference plots. The presence of a cover crop mixture and cereal rye delayed the critical timing for weed removal (CTWR) by approximately 2 wk compared with winter fallow. The results in 2019 showed the predicted duration of CPWC following cover crop mixture, cereal rye, and winter fallow was 4.8 wk, 0 wk, and 5.1 wk, respectively. Furthermore, in 2020, the estimated CPWC duration following cover crop mixture, cereal rye, and winter fallow was 1.4 wk, 0.1 wk, and 2.6 wk, respectively. In both years, single-species cereal rye resulted in the shortest CPWC due to its early-season weed suppression, while winter fallow resulted in the longest CPWC duration. In conclusion, a shorter duration of CPWC with the incorporation of cover crops could help soybean growers enhance their weed control and provide greater yield protection to soybeans.
Kumari et al. (2026) studied this question.