Abstract/Contents: | "Field studies were conducted at three locations in central Texas and along the upper Texas Gulf Coast to evaluate various turf herbicides for phytotoxicity, coverage over time, and harvestability on 'Raleigh' St. Augustinegrass (Stenotaphrum secundatum), 'Tifway 419' hybrid bermudagrass(Cynodon spp.) , and 'Palisades' Zoysiagrass(Zoysia japonica). St. Augustinegrass was present at all three locations while bermudagrass and Zoysiagrass was present at one location. Herbicides selected were based on mode of action which included growth regulators (Trimec Southern, Confront, Lontrel, and Drive), photosynthesis inhibitors (Atrex, Basagran, Buctril, and Princep), amino acid synthesis inhibitors (Image, Manage, Manor, and Plateau), lipid synthesis inhibitors (Acclaim Extra), organic arsenicals (MSMA), and seedling growth inhibitors (Asulam, Balan, Barricade, Betasan, Dimension, Gallery, Pennant, Pendulum, Prograss, Ronstar, and Surflan). Herbicides were applied with a hand-held, six foot boom calibrated to deliver 20 to 40 GPA approximately 14 days after turf harvest in mid to late May at two locations and late July at another location. Plot design was a randomized complete block with 3 replications per location. Plot size was 6 ft wide by 10 ft long for each treatment. Percent ground cover was evaluated periodically throughout the growing season using a visual scale (0=no growth, 100=complete growth) and also using Sigma Scan Technology. Phytotoxicity was also evaluated (0=none, 5=complete death). At approximately 170 days after treatment, plots were rated for harvestability (0=not harvestable, 5=completely harvestable). Phytotoxicity on St. Augustinegrass was significant higher from the untreated check with Acclaim Extra, Drive, and MSMA at all three locations. Plateau resulted in significant toxicity at two locations, while Confront, Image, and Simazine caused significant phytotoxicity at only one location. With hybrid bermudagrass, Acclaim Extra, Plateau, and Prograss caused phytotoxicity while on zoysiagrass Manor, Plateau, and Prograss resulted in significant phytotoxicity. Ribbon recovery on St. Augustinegrass was significantly reduced when compared with the untreated check by Acclaim Extra, Drive, Image, Manor, and Plateau at all three locations; Manage and Surflan at two locations; and Barricade, Confront, Gallery, MSMA, and Pendulum at only one location. With hybrid bermudagrass, Gallery, Image, Manor, Plateau, Prograss, and Surflan reduced recovery while with zoysiagrass, Betasan, Manor, Plateau, Prograss, and Surflan reduced ribbon recovery. Plateau reduced St. Augustinegrass harvesability at two locations while Betasan, Drive, Image, Manage, Manor, and Surflan reduced harvestability at one location. Hybrid bermudagrass harvestablity was reduced by Image, Plateau, and Prograss." |