Purple Nutsedge (Cyperus rotundus) Control with Imazaquin in Warm-Season Turfgrasses

Postemergence applications of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} controlled higher levels of purple nutsedge (Cyperus rotundusL. # CYPRO) in common bermudagrass [Cynodon dactylon(L.) Pers.] and hybrid bermudagrass (′Tifgreen’ and ‘Tifdwarf′,C. dactylon×C. transvaalensisBurtt-Davy) than monosodium salt of methylarsonic acid (MSMA). Control was better at 560 or 840 g ai/ha of imazaquin than at lower rates. Postemergence applications of imazaquin plus 2240 g ai/ha of MSMA controlled more purple nutsedge than equivalent rates of imazaquin alone. Preemergence applications of imazaquin were not effective. Bermudagrass discoloration was observed in some experiments on turfs mowed at a height of 1.3 cm or less but usually disappeared within 2 to 3 weeks, especially when MSMA was used in combination with imazaquin. No injury was observed on bermudagrasses, zoysiagrass (Zoysia japonicaSteud. ‘Meyer′), St. Augustinegrass [Stenotaphrum secundatum(Walt.) Ktze. ‘Raleigh′], and centipedegrass [Erernochloa ophiuroides(Munro) Hack.] maintained at mowing heights above 1.3 cm.