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 rotundus L. # CYPRO) in common bermudagrass [Cynodon dactylon (L.) Pers.] and hybrid bermudagrass (′Tifgreen’ and ‘Tifdwarf′, C. dactylon × C. transvaalensis Burtt-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 japonica Steud. ‘Meyer′), St. Augustinegrass [Stenotaphrum secundatum (Walt.) Ktze. ‘Raleigh′], and centipedegrass [Erernochloa ophiuroides (Munro) Hack.] maintained at mowing heights above 1.3 cm.

Sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio) propyl]-3-hydroxy-2-cyclohexen-1-one} at 0.34 kg ai/ha, fluazifop {(+)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} at 0.13 kg ai/ha, and SC-1084 {3-hydroxy-4-[4-[[5-trifluoromethyl)-2-pyridinyl] oxy] phenoxy] pentanoic acid} at 0.28 kg ai/ha controlled ‘Tifway’ bermudagrass [Cynodon transvaalensis Burtt-Davy #3 CYNTR] x [Cynodon dactylon (L.) Pers. # CYNDA] nearly 100% when applied for 2 consecutive years. Tall fescue (Festuca arundinacea Schreb. ‘Ky 31’ # FESAR) tolerated fluazifop at 0.13 kg/ha and SC-1084 at 0.07 to 0.28 kg/ha; however, centipedegrass [Eremochloa ophiuroides (Munro) Hack, ‘common’ #ERLOP] and zoysiagrass (Zoysia japonica Steud. # ZOYJA x Zoysia tenuifolia Willd. ex trin. ‘Emerald’ #ZOYTE did not tolerate these treatments. Centipedegrass tolerated sethoxydim, zoysiagrass tolerance was intermediate, and tall fescue was injured severely. Sethoxydim at 0.22 kg/ha discolored leaves of zoysiagrass, but the turf recovered fully. Thus, bermudagrass, when mixed with either tall fescue, centipedegrass, or zoysiagrass, can be controlled selectively with herbicides applied postemergence.