Creeping bentgrass infestations in cool-season turfgrass are unsightly and difficult to control. Field tests were conducted at Stoney Creek Golf Course in Wintergreen, VA, in 2002 and 2003 on a Kentucky bluegrass rough and at the Turfgrass Research Center in Blacksburg, VA, in 2003 on a perennial ryegrass lawn to determine the efficacy of imazaquin, isoxaflutole, and mesotrione for creeping bentgrass control and turfgrass tolerance. Isoxaflutole and mesotrione each applied in two sequential applications at 280 g ai/ha or three sequential applications at 170 or 60 g/ha and imazaquin in two sequential applications at 390 g/ha controlled bentgrass at least 92% 14 wk after initial treatment (WAIT) at all locations. Sequential applications were applied at 2-wk intervals. Isoxaflutole and mesotrione, regardless of rate or sequential treatment, injured turfgrass less than 20% at all rating dates and locations. Imazaquin in two sequential applications at 390 g/ha injured Kentucky bluegrass and perennial ryegrass greater than 50% at all locations 14 WAIT. Results indicate isoxaflutole or mesotrione could be used for selective bentgrass control in Kentucky bluegrass or perennial ryegrass.
Nomenclature: Imazaquin; isoxaflutole; mesotrione; creeping bentgrass, Agrostis stolonifera L. #3 AGRST; Kentucky bluegrass, Poa pratensis L. ‘Blacksburg’ and ‘Midnight’; perennial ryegrass, Lolium perenne L. ‘Prosport’.
Additional index words: Golf course rough, turfgrass injury, weed control.
Abbreviations: SCG, Stoney Creek Golf Course; TRC, Turfgrass Research Center; WAIT, weeks after initial treatment.