Dollar Spot Disease name comes from the silver-dollar sized straw-colored spots this disease causes on putting greens. On longer grass, the shapes are more irregular. When dew is on the grass, look for white cob-webby fungus. Blades of grass show straw-colored lesions with reddish-brown borders. Of the common lawn grass, bluegrasses and fescues are most affected. Improper mowing, watering and excessive thatch buildup are all contributing factors.