Estimation of acetic acid as a natural-product herbicide for controlling purple nutsedge weed associated with maize plants in organic agriculture

Purple nutsedge ( Cyperus rotundus L.) is a highly invasive perennial weed known for its wide distribution, fast growth, and adaptability across various cropping systems. In organic farming, controlling this persistent weed poses a significant challenge due to limited safe and effective management options. Therefore, greenhouse experiments were conducted to evaluate the response of purple nutsedge and maize plants to acetic acid as a natural-product herbicide at three successive concentrations (2.5, 5.0, and 7.5%). Additionally, this study investigated pre-emergence and post-emergence application of acetic acid to estimate the most efficient time of application. The results revealed that post-emergence application of acetic acid at all tested concentrations proved more effective than pre-emergence application in suppressing the growth parameters of purple nutsedge at both 45 and 90 days after sowing. Although 7.5% post-emergence application of AA achieved the strongest suppression of P. nutsedge, 5.0% AA applied post-emergence provided the most favorable balance between weed control and maize growth, resulting in the highest maize growth values among the tested treatments. The improvement in maize growth was mainly associated with reduced competition from P. nutsedge. Therefore, post-emergence application of 5.0% AA represents a promising treatment for further evaluation. Nevertheless, these results were obtained under greenhouse conditions and field scale studies are required to verify crop safety, persistence of weed suppression, application requirements, and effects on final maize yield.