This disease is prevalent in April, May, and June and again in September and October when the weather is cool and wet.
Damage is greatest on lawns that are deficient in nitrogen.
The characteristic symptom on the bentgrass turf is the appearance of dark, water-soaked spots about the size of silver dollars. These turn brown, but later are bleached to a light tan. As the disease develops, the spots merge and large irregular areas cover the lawn. In the early morning, when dew is on the grass, a fine white cobwebby growth can be seen on the grass blades. This is the fungus mycelium.