Suppression of seashore paspalum in bermudagrass with herbicides.
A mixture of P. vaginatum with Cynodon spp. results in an overall poor quality turf on golf course fairways. A field experiment was conducted at two locations in Hawaii during 1997 to determine if herbicides would control P. vaginatum encroachment without causing undesirable injury to the Cynodon spp. Three applications of Asulox (asulam) applied alone at a total rate of 4.4 kg/ha or with Image (imazaquin) suppressed P. vaginatum by ≥97% by 8 weeks after the initial treatment and ≥83% by 10 weeks. The suppression from 3 applications of Trimec Plus (MSMA + 2,4-D + mecoprop + dicamba) at a total rate of 11.1 kg/ha was ≥63% at 8 weeks and ≥70% by 10 weeks. P. vaginatum suppression from an initial application with Trimec Plus followed by two Asulox treatments was not advantageous, compared with three Asulox treatments. Three applications of Trimec Plus suppressed at least 70% P. vaginatum by 10 weeks. The suppression was poor when treated with Ally (metsulfuron) and sequential applications with Surflan (oryzalin) and MSMA. Tifway bermudagrass (C. transvaalensis × C. dactylon) was severely injured when treated with all these herbicides except Ally and Surflan plus MSMA. Maximum injury ranged from 40% when treated sequentially with Trimec Plus and Asulox, to 50% when treated with Asulox, 57% when treated with Asulox plus Image, and 91% when treated with Trimec Plus. By 10 weeks, Cynodon spp. had started to recover but the overall injury ranged from 28 to 40%.