Removal of Creeping Bentgrass from Kentucky Bluegrass with Mesotrione

Creeping bentgrass (Agrostis stolonifera L.) creates a dense, high-quality playing surface on golf courses, but often encroaches adjacent areas of Kentucky bluegrass (Poa pratensis L.). Callisto, a herbicide produced and marketed by Syngenta containing the active ingredient mesotrione, provides preemergence and postemergence control of broadleaf and annual grassy weeds. Preliminary field trials show that mesotrione kills creeping bentgrass, but more information is needed regarding the application protocol. Research was conducted to determine: 1) what rates of mesotrione are best for removing creeping bentgrass from Kentucky bluegrass, and 2) what mesotrione rates are safe for Kentucky bluegrass