2017 ASHS Annual Conference

Seashore paspalum (Paspalum vaginatum) has seen increased popularity in Hawaii due to use of non-potable water on various sports venues. Bermudagrass (Cynodon dactylon) and goosegrass (Eleusine indica) are problem weeds infesting both fairways and greens in many seashore paspalum golf courses. Herbicide efficacy studies were conducted at the Pali Golf Course (greens cut, cv. Salam), in windward Oahu, and the Hoakalei (fairway cut, cv. SeaDwarf) and West Loch (greens cut, cv. Salam) Golf Courses on leeward Oahu. The herbicides metribuzin, topramezone, mesotrione, and ethofumesate were evaluated alone and in tank mixtures for Bermudagrass and goosegrass control and seashore paspalum injury. At the Pali Golf Course maximum goose grass control in seashore paspalum greens was obtained with a tank mix of metribuzin (0.11 kg ai/ha), topramezone (0.010 kg ai/ha), and mesotrione (0.056 kg ai/ha). However, seashore paspalum injury was severe. Excessive bleaching of turf foliage caused by mesotrione and topramezone was significantly reduced with the addition of metribuzin to the tank mix. At the Hoakalei Golf Course 2, 3, and 4-way tank mixes of metribuzin (0.21 kg ai/ha), topramezone (0.021 kg ai/ha), mesotrione (0.056 kg ai/ha), and ethofumesate (0.94 kg ai/ha) were evaluated for Bermudagrass management in seashore paspalum maintained at a fairway cut. Unacceptable turf injury was obtained in all treatments that did not include metribuzin. Although the 3-way tank mixes of metribuzin, mesotrione, ethofumesate and metribuzin, topramezone, ethofumesate provided acceptable seashore paspalum turf discoloration, long-term suppression of Bermudagrass was not obtained. Turf foliage bleaching caused by mesotrione and topramezone was further reduced with the addition of ethofumesate to the tank mix. Goose grass in seashore paspalum greens at the West Loch Golf Course was controlled with 3-way tank mix of metribuzin (0.11 kg ai/ha), topramezone (0.010 kg ai/ha), and ethofumesate (0.94 kg ai/ha) with an acceptable level of discoloration of the turf. Overall, tank mixes of metribuzin, topramezone, mesotrione, and ethofumesate have the potential for post-emergent goosegrass control and bermudagrass suppression in seashore paspalum turf.