Application Timing Affects Tolerance of Zoysiagrass to Fluazifop‐P‐butyl and Safening Effect of Triclopyr (original) (raw)

Z oysiagrass (Zoysia spp.) is a warm-season turfgrass widely adopted in the transitional zone and southeastern regions of the United States due to good turf quality and low nutrient input requirements. Zoysiagrass exhibits more shade and winterkill tolerance than bermudagrass (Cynodon spp.), fewer disease and insect problems than St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze], and moderate salinity tolerance and wear tolerance compared with other warm-season grasses (Patton, 2010; Patton et al., 2017a). The most troublesome weeds in zoysiagrass turf are frequently other warm-season grasses with a similar growth habit and growing season. For example, bermudagrass is often one of the most problematic weeds to control, especially for golf courses during the process of transitioning from bermudagrass to zoysiagrass fairways (Johnson, 1992). Use of nonselective herbicides for long-term bermudagrass control is usually not practical and can be costly, since bermudagrass will eventually regrow from rhizomes and compete with the zoysiagrass (Johnson and Carrow, 1995). The aryloxyphenoxyproponiate (AOPP) herbicide fluazifop-P-butyl is labeled for bermudagrass suppression in zoysiagrass; however, previous studies reported significant injury to zoysiagrass despite nearly 100% control of bermudagrass (Johnson, 1987). Finding ways to increase the rate of AOPP