Suppression of Dollar Spot on Creeping Bentgrass and Annual Bluegrass Turf with Compost-Amended Topdressings. Eric B. Nelson, Assistant Professor, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca 14853. Cheryl M. Craft, Research Support Specialist II, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca 14853. Plant Dis. 76:954-958. Accepted for publication 24 April 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0954.

Topdressings formulated with mixtures of sand and various composts or organic fertilizers (70:30, v/v) were applied to putting greens of creeping bentgrass and annual bluegrass and evaluated for their ability to suppress dollar spot disease development. When applied as preventive treatments at monthly intervals, topdressings amended with selected commercial organic fertilizers composed of animal and plant meals were highly suppressive to dollar spot consistently over a 3-yr period. The level of suppression in some experiments did not differ from that of the fungicide propiconazole. Additionally, a poultry litter compost and a 2.5-yr-old sludge compost from Endicott, New York, also were consistently suppressive to dollar spot. All effective amendments remained suppressive for up to 1 mo after application, but by 2 mo after application, dollar spot incidence did not differ among treatments. When curative treatments of a poultry-cow manure compost, a sludge compost, and an organic fertilizer composed of animal and plant meals were compared with the fungicide iprodione, only the organic fertilizer and the poultry-cow manure compost were effective in reducing dollar spot severity. Results indicated that application of certain composts and organic fertilizers to golf course turf may suppress dollar spot symptoms as effectively as conventional fungicides.

Keyword(s): biological control, cultural control, Sclerotinia homoeocarpa.