Application of Glufosinate on Dormant Zoysiagrass (Zoysia japonica) Turf

Abstract

Winter application of glyphosate on dormant zoysiagrasses (Zoysia spp.) is a common practice for control of fall-emerging weeds in the upper transition zone. However, repeated application can lead to selection of resistant weed populations. This study evaluated glufosinate, another non-selective herbicide, for weed control and safety on dormant zoysiagrass turf. Field plots were established on three sites during two growing seasons. At two application timings, glufosinate at rates of 0.84 or 1.68 kg·ha−1 were compared with glyphosate at 0.56 kg·ha−1 and a nontreated control. Application timings included 2 to 3 weeks or 2 to 3 days before zoysiagrass spring green-up. Regardless of rate, glufosinate was similar in effectiveness to glyphosate for control of annual bluegrass (Poa annua L.) and mouseear chickweed (Cerastium vulgatum L.). Application timing significantly affected phytotoxicity on zoysiagrass turf. For applications at 2 to 3 weeks before initiation of zoysiagrass green-up in spring, no negative impact on zoysiagrass was found. However, when applications were made within days of zoysiagrass resuming growth, both glufosinate and glyphosate reduced turf quality up to 40%. This study suggests that glufosinate can be an alternative to glyphosate for weed management on dormant zoysiagrass turf, but applications should be timed at least 2 weeks before initiation of spring growth.