Centers of the spots may recover, resulting in rings of diseased grass. Leaves and sheaths turn olive green, wilt, become light brown, and die. Stems, crowns, and roots also may be infected. In light attacks, roots and crown usually are not involved, and plants recover.
All lawn grasses are susceptible.
Rhizoctonia solani , a soil-inhabiting fungus. This fungus may survive on soil organic matter and thatch. Sclerotia are the chief overwintering structures. The disease is most common in the summer months and in warm, inland areas. Poorly drained soils, thatch, and night irrigation lengthen the period of leaf wetness and promote infection.