Use of Appear II in Fungicide Programs for Control of Dollar Spot Disease with Effects on Localized Dry Spot in a Creeping Bentgrass Putting Green in Chicago, IL, 2023

Dollar spot, caused by Clarireedia jacksonii, is a chronic fungal disease of creeping bentgrass in cool, humid environments in the United States. In closely mown golf playing surfaces, symptoms include small, circular, sunken spots of blighted turf that eventually coalesce if left untreated. This report evaluates the efficacy of preventative fungicide programs to suppress dollar spot in golf greens. Programs contained broad spectrum fungicides mixed with Appear II, a systemic potassium phosphite fungicide that is formulated with a green pigment. A study was conducted on an ‘L-93’ plus ‘Providence’ creeping bentgrass ( Agrostis stolonifera) push-up constructed nursery green originally seeded in 2000 at the North Shore Country Club in Glenview, IL. Results indicated fungicide programs that contained Appear II can provide complete control of dollar spot and can also significantly reduce localized dry spot, an abiotic disorder of turfgrass caused by hydrophobic soils, which commonly occurs in sand-based putting greens.