Evaluation of Herbicides and Tank-Mixes for Suppression of Bermudagrass in Zoysiagrass

Zoysiagrass (Zoysia spp.) is a popular turfgrass species for use on lawns, sod farms, and golf courses in the transitional and southern climatic zones of the U.S. One common problem in managing zoysiagrass is the contamination and subsequent removal of bermudagrass (Cynodon spp.). Fluazifop and fenoxaprop are utilized for bermudagrass control in zoysiagrass and zoysiagrass injury from these herbicides can be reduced by tank-mixing these herbicides with triclopyr, a synthetic auxin herbicide. Aminocyclopyrachlor, another synthetic auxin herbicide, has similar potential for reducing injury to zoysiagrass. Research was conducted in Fayetteville, Arkansas and Auburn, Alabama to evaluate aminocyclopyrachlor, fluazifop, fenoxaprop, triclopyr, and their combinations for bermudagrass suppression in zoysiagrass. Fluazifop at 0.105 kg active ingredient (ai) ha^-1 suppressed bermudagrass most, but this application caused unacceptable injury and quality reduction to zoysiagrass. Tank-mixing fluazifop or fenoxaprop at 0.14 kg ai ha^-1 with triclopyr at 0.56 kg acid equivalent (ae) ha^-1 reduced zoysiagrass injury and improved turf quality over fluazifop or fenoxaprop alone. Fluazifop + triclopyr provided more bermudagrass suppression than fenoxaprop + triclopyr. Aminocyclopyrachlor (0.026 or 0.071 kg ae ha^-1  ) did not reduce herbicide injury from fluazifop or fenoxaprop applications to zoysiagrass and did not provide significant bermudagrass suppression. Results suggest that fluazifop + triclopyr and fenoxaprop + triclopyr remain the best treatments for bermudagrass suppression in zoysiagrass because they provide bermudagrass suppression without reducing zoysiagrass quality.