Purple nutsedge is a competitive and persistent perennial weed in the agronomic and horticultural cropping systems of the southeastern United States. Its management is a challenge during the growing season due to its ability to propagate vegetatively through underground rhizomes and tubers. Therefore, effective herbicide programs are needed that can check the spread of purple nutsedge and protect crop yields. Greenhouse experiments were conducted in 2024 to evaluate the response of purple nutsedge at two different growth stages (10 to 15 cm and 15 to 20 cm heights) to herbicides currently labeled for use in Mississippi cropping systems. Herbicides tested were glyphosate at 1,260 g ai ha–1, glufosinate at 672 g ai ha–1, bentazon at 1,680 g ai ha–1, halosulfuron at 69.5 g ai ha–1, and trifloxysulfuron at 6.9 g ai ha–1. Glyphosate was the most effective herbicide against purple nutsedge, providing >90% control, followed by halosulfuron, which provided 70% to 90% control at both growth stages. New shoot emergence was highest when glufosinate and bentazon were applied, and no new shoots emerged when glyphosate and halosulfuron were applied. More new shoots were observed when glufosinate and bentazon were applied when plants were 15 to 20 cm high compared to 10 to 15 cm. Shoot regrowth at 21 d after cutting the aboveground shoots indicated similar trends. A reduction of >90% in shoot and root biomass was observed when glyphosate, halosulfuron, and trifloxysulfuron were applied, whereas glufosinate and bentazon applications resulted in 50% less biomass reduction. Overall, herbicide efficacy against purple nutsedge was greater when plants were treated at the recommended height of 10 to 15 cm rather than 15 to 20 cm. The study results indicated that both herbicide mode of action and application timing are important for better purple nutsedge management in cropping systems.

Herbicide resistance poses an escalating challenge to successful weed management in contemporary cropping systems, prompting growing interest in integrated strategies to reduce reliance on herbicides. Although cover cropping has long been recognized for its potential to suppress weeds, it has recently gained renewed attention as a weed management tool and for its ability to help producers achieve broader goals of soil health and environmental sustainability. Although research on its efficacy in the midsouthern United States has accumulated, a meta-analytic synthesis has been lacking. This meta-analysis synthesized 746 effect sizes from 27 peer-reviewed studies (selected based on explicit reporting of weed suppression metrics, conducted in the midsouthern United States between 1991 and 2023) to assess cover crop weed suppression in the midsouthern region, which includes Alabama, Arkansas, Louisiana, Mississippi, eastern Oklahoma, Tennessee, and eastern Texas. Six key moderators and their two-way interactions were evaluated: tillage status of no-cover-crop controls, cover crop termination timing, weed control evaluation timing, cover crop type, weed functional group, and crop type, using a multivariate framework capturing study-level variation. The overall effect size was 36 (confidence interval [CI], 25–47], with most moderator levels showing positive effect sizes. Suppression was pronounced against no-till controls (mean difference [MD] = 43; CI, 30–55), while tilled controls exhibited moderated effects (MD = 27; CI, 14–39) due to the inherent weed suppression provided by tillage. Effects were greater for early evaluation timing (MD = 47; CI, 33–61) than late timing (MD = 34; CI, 20–48). Grass-legume mixtures provided the greatest suppression (MD = 70; CI, 56–84), while brassicas were ineffective (MD = 13; CI, 0–27). However, substantial two-way interactions among these moderators were prevalent, accompanied by high heterogeneity, indicating complex context specificity. Nonetheless, these findings highlight the weed suppression potential of cover crops and provide agroecologically informed quantitative insights into using cover crops for weed management in the region.