Dollar spot

Symptoms. On fine textured and close-cut turf, the disease appears as round, brown to straw-colored and somewhat sunken spots approximately the size of a silver dollar. In coarse textured grasses maintained at taller cutting heights, the dead spots are larger and more diffuse. Spots are often seen in clusters. Dollar spot is readily distinguished from other turf disease by light-tan lesions with a reddish-brown border on the leaf blades of live plants near the edge of the affected area. On fine bladed grasses, the lesions usually girdle the leaf blade. Early in the day or in periods of extended dew, cobweb-like mycelium of the fungus can be seen growing on affected areas. During early stages of the disease, affected plants may appear water-soaked and wilted, but spots quickly fade to a characteristic straw color. The mycelium found on foliage is often confused with that of Pythium, Nigrospora, and Rhizoctonia.
Disease cycle. The pathogen overwinters and survives unfavorable periods as dormant mycelium on infected plants and plant debris. In addition to mycelium, dollar spot survives harsh environments in stromata on leaf surfaces. Apothecia occasionally are formed by the pathogen, but are sterile. Sexual spores have not yet been discovered in North America.
Dissemination of the pathogen is restricted to the movements of infected leaf debris via equipment, people, animals, wind, or water. When environmental conditions become favorable for pathogen activity (warm, humid, high moisture in canopy), the dormant mycelia and stromata on the infected debris resume growing on the plant tissues. If moisture is sufficient in the turf canopy, mycelium can begin to penetrate new leaves and new host, causing infection.