Turfgrasses have been utilized by humans for >10 centuries to enhance their environment, but the modern turfgrass industry developed primarily during the past three decades, largely in response to increased population growth and urbanization. Turfgrass culture represents an important economic component of horticulture in North America with annual expenditures of $25 to $45 billion in the United States between 1982 and 1993 (Beard and Green, 1994; Gibeault and Cockerham, 1985). In return, turfgrass provides numerous benefits, including functional (e.g., reduction of soil erosion, pollution, and noise), recreational (e.g., provision of recreational surfaces for improved health and safety), and aesthetic benefits (e.g., improved aesthetic value and community pride) (Beard and Green, 1994; Gordon et al., 1996). Because of these economic and environmental benefits, turfgrass and turfgrass health have become increasingly important. Dollar spot (Sclerotinia homoeocarpa F.T. Bennett) is one of the most important diseases that affect turfgrass; it can cause considerable damage, particularly to highly maintained golf course putting greens, closely mown fairways, and bowling greens (Goodman and Burpee, 1991). This disease can also damage less intensively managed turfgrass grown on home lawns, recreational and athletic facilities, and educational or industrial properties. Dollar spot reduces the aesthetic and playing quality of infected turf, and can contribute to weed encroachment and plant death (Fig. 1) (Smith et al., 1989). Dollar spot is a widespread disease that affects many turfgrass species throughout North America, Central America, Australia, New Zealand, Japan, the British Isles, and continental Europe (Couch, 1995; Fenstermacher, 1980; Vargas, 1994). Except for western Canada and the Pacific northwest region of the United States, dollar spot is the most common disease of turf in North America (Couch, 1995). The persistent nature of this disease in turfgrass swards often requires intensive control measures. As a result, more money is spent to manage dollar spot than to control any other turfgrass disease on golf courses (Goodman and Burpee, 1991).