Tolerance of Five Warm-Season Turfgrass Species to Flumioxazin

Flumioxazin provides PRE and POST, annual weed control in dormant bermudagrass, but applications during active growth may be injurious. Flumioxazin could also provide an alternative chemistry for POST annual bluegrass control in other turfgrasses, but research is limited on tolerance levels. The objective of this research was to evaluate tolerance of five warm-season turfgrasses to flumioxazin applied at various rates and timings. Late-winter applications of flumioxazin at 0.21, 0.42, or 0.84 kg ai ha(-1) caused acceptable (< 20%) injury to bermudagrass, seashore paspalum, St. Augustinegrass, and zoysiagrass at 3, 6, and 9 wk after treatment (WAT) in both years. In 2012, late-winter applications to centipedegrass caused unacceptable injury at 6 WAT, but turf recovered to acceptable levels by 9 WAT at all rates. Applications made during active turfgrass growth caused unacceptable initial injury to all species. However, bermudagrass, seashore paspalum, St. Augustinegrass, and zoysiagrass recovered to < 20% injury by 9 WAT from all rates. In 2012, centipedegrass treated in midspring had 0, 24, and 74% injury from flumioxazin at 0.21, 0.42, and 0.84 kg ha(-1)., respectively, at 9 WAT. In 2013, midspring applications to centipedegrass caused 13, 48, and 71 % injury from 0.21, 0.42, and 0.84 kg ha(-1), respectively at 9 WAT. Overall, flumioxazin has the potential to control annual weeds in bermudagrass, seashore paspalum, St. Augustinegrass, and zoysiagrass with late-winter applications before greenup, but all turfgrasses may be excessively injured during active growth.