<i>Zoysia</i> spp. putting green tolerance to postemergence herbicides

Abstract Species of Zoysia Willd. are used on approximately 9550 ha of golf course surfaces throughout the United States, primarily fairways and tees in transitional climates. Recently, cultivars featuring dwarf canopy height and improved quality have been released for putting green use; however, tolerance of these cultivars to postemergence herbicides is unknown. Field research was conducted in 2021 and 2022 evaluating the tolerance of Prizm ® [ Zoysia matrella (L.) Merr.] and Lazer ® [ Z. matrella (L.) Merr. × Zoysia minima (Colenso) Zotov] zoysiagrass to pyrimisulfan + penoxsulam (Aethon™), pyrimisulfan (Arkon™), flazasulfuron (Katana ® ), 2,4‐D + quinclorac + dicamba + sulfentrazone (Q4 ® Plus), 2,4‐D + MCPP + dicamba + carfentrazone (SpeedZone ® EW), 2,4‐D + MCPP + dicamba + sulfentrazone (Surge ® ), and pyrimisulfan (formulated as a granule; Vexis ® ). A nontreated check was included for comparison. All of these herbicides have commercial labeling for use on zoysiagrass ( Zoysia Willd.); however, none of these herbicides have labeling for use on zoysiagrass putting greens. Application rates in this study exceeded label maximums (for use on zoysiagrass) to ascertain the upper limits of Prizm ® and Lazer ® tolerance to these herbicides in Knoxville, TN and College Station, TX, respectively. Plots were arranged in randomized complete block design with four replications at both sites. Turfgrass injury was visually evaluated with data subjected to analysis of variance. Prizm ® in Tennessee exhibited commercially acceptable tolerance to the applied herbicides, resulting in ≤8% injury either year. Lazer ® in Texas sustained injury ranging from 21% to 61% and 10% to 31% in 2021 and 2022, respectively. Conditions of extreme heat and drought in Texas may have exacerbated differences in Lazer ® tolerance to applied herbicides between years. Additional research across varying geographies and environmental conditions is needed to better understand tolerance of new zoysiagrass putting green lines, particularly within Z. minima .