Early and Late Postemergence Control of Dallisgrass in Tall Fescue

摘要

Dallisgrass (Paspalum dilatatum Poir.) is a problematic turfgrass weed throughout the southern United States. A two-year study was conducted evaluating applications of fluazifop at 105 g/ha, mesotrione at 280 g/ha, and fluazifop + mesotrione at 105 +280 g/ha, respectively, for control of dallisgrass in tall fescue (Festuca arundinacea). Treatments were applied in early spring shortly after dallisgrass broke dormancy [< 160 growing degree days (GDD10C)] and early summer well after dallisgrass broke dormancy (> 500 GDD10C). Yearly accumulated GDD10C values were calculated using a base temperature of 10deg C beginning on 1 January. Applied at < 160 GDD10C in 2008, a single application of fluazifop provided 73% control of dallisgrass at 28 days after treatment (DAT) and 90% control at 76 DAT. When applied at > 500 GDD10C in 2008, a single application of fluazifop only provided 46% and 0% control of dallisgrass at 28 and 76 DAT, respectively. Similar trends were also observed with sequential applications each year. Dallisgrass control with fluazifop + mesotrione was not greater than fluazifop alone at either timing. These data suggest dallisgrass is more susceptible to fluazifop when emerging out of dormancy in early spring.