Homeowners may find a cottony fungus on their grass, which is often the result of a fungal disease. Fungal growths on grass adversely affects the health of the lawn, as well as its appearance.
Pythium blight is a fungal disease also known as cottony blight. This disease affects all types of turfgrass and is most common during hot, humid weather. Pythium blight spreads rapidly and can kill large portions of grass in a short time. Powdery mildew is another fungal disease that affects lawn grass, especially in shaded areas. Shade, high humidity and and improper aeration favors the development of powdery mildew.
Pythium blight causes small blighted patches of grass, which often appear greasy. As time goes by, grass blades wilt and the patches turn brown. During the early morning, a cottony fungal growth is present on lawn grass. Powdery mildew causes grass blades to develop a white, cottony substance that turns grass yellow. Eventually, patches of grass die as a result.
Controlling cottony fungal growths in your lawn is best accomplished with fertilization, proper watering practices and fungicide applications. Repeat fungicide applications as necessary until symptoms are controlled.