Annual Bluegrass Control and Tolerance of Kentucky Bluegrass and Perennial Ryegrass to Ethofumesate

Abstract

Abstract Various rates of ethofumesate were evaluated for annual bluegrass (Poa annua L.) control in a perennial ryegrass (Lolium perenne L.) fairway. The tolerance of ‘Merion’, ‘Mystic’, and a blend of Kentucky bluegrasses (Poa pratensis L.) to ethofumesate also was assessed. Ethofumesate at 0.84, 1.1, and 0.84 + 0.84 kg·ha–1 provided poor annual bluegrass control; 2.2 and 1.1 + 1.1 kg·ha–1 provided good control; and 2.2 + 1.1 and 2.2 + 2.2 kg·ha–1 provided excellent control. Overall quality of Kentucky bluegrass was only slightly reduced by ethofumesate at 1.1 or 2.2 kg·ha–1; however, split applications at 2.2 + 1.1 and 2.2 + 2.2 kg·ha–1 severely reduced bluegrass cover and overall quality for 7 months. Foliar growth of sequentially treated Kentucky bluegrass appeared suppressed throughout fall and winter. Between January and April, Kentucky bluegrass plots treated with split applications of 2.2 + 1.1 or 2.2 + 2.2 kg·ha–1 had a dark-green color. No visual injury was observed in perennial ryegrass. Ethofumesate applied at 2.2 or 1.1 + 1.1 kg·ha–1 provided the best combination of safety to Kentucky bluegrass and control of annual bluegrass. Chemical names used: (±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate (ethofumesate).