Nonsynthetic herbicides for turfgrass: Optimizing performance of acid‐ and oil‐based chemicals via sequential treatment to dormant turfgrass

Abstract Consumer demand for certified‐organic weed control in turfgrass has grown, yet information on nonsynthetic herbicide performance, safety, and environmental impacts is limited. This study evaluated several acid‐ and oil‐based chemicals and synthetic comparisons for winter weed control in dormant bermudagrass [ Cynodon dactylon × C. transvaalensis (Pers. L.) ‘Latitude 36’] and zoysiagrass [ Zoysia matrella (L.) Merr. ‘Cavalier’]. Four nonsynthetic herbicides (ammonium nonanoate, acetic acid, citric acid + clove oil, and d‐limonene) applied twice or thrice were compared to glufosinate and glyphosate applied once. Acetic acid was also tested at three concentrations (20%, 30%, 40%) when applied thrice. Results showed that acetic acid consistently controlled corn speedwell ( Veronica arvensis L.) and common chickweed [ Stellaria media (L.) Vill] as well as glufosinate and glyphosate, but annual bluegrass ( Poa annua L.) control by acetic acid was concentration‐ and application frequency‐dependent. Other nonsynthetic chemicals did not acceptably control any of the weeds evaluated at 91 days after treatment. Acetic acid applied thrice controlled annual bluegrass similar to glufosinate and glyphosate. However, lower concentrations of acetic acid were less effective against mature annual bluegrass. The study highlights the potential of acetic acid as an organic herbicide for weed control in turfgrass, especially for broadleaf weeds. However, organic chemicals cost 240–2370 times more than glyphosate and deliver 132–1596 times more active ingredient into the environment. Further research on optimizing application strategies is warranted to enhance weed control efficacy, equitable access, and environmental sustainability of organic weed control in turfgrass systems.