Tuesday, November 14, 2006

Blue Grama Seedling Tolerance to Postemergence Herbicides.

Shane M. Andersen and Leo C. Schleicher. South Dakota State Univ, Brookings, SD 57007-0996

Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] is a warm-season grass species that has shown potential as a reduced-input turf. Blue grama turf establishment could be improved using effective weed management strategies, including herbicides.  Imazapic is the only postemergence herbicide currently labeled in blue grama turf and little information is available on blue grama seedling tolerance to herbicides.  In 2005 and 2006, 17 postemergence herbicides were applied to field plots of blue grama seedlings at the 3 to 4-leaf stage.  Plots were evaluated for visual herbicide injury at 3, 5, 7, 10, 14, 21, and 28 days after treatment (DAT) and percent blue grama coverage at 7, 14, 21, and 28 DAT.  Preliminary results suggest seedling tolerance to fluroxypyr, triclopyr, clopyralid, 2,4-D, fenoxaprop-ethyl, simazine, metsulfuron methyl, and halosulfuron methyl.  Quinclorac, imazapic, MSMA, carfentrazone-ethyl, and dicamba caused initial minor injury, but seedlings generally recovered at 28 DAT.    Mesotrione and isoxaflutole caused significant bleaching, stunting and turfgrass coverage reduction at all rating dates.    Results from this study indicate that several postemergence herbicides may safely be applied to seedling blue grama to control problematic weeds during establishment.