What can I do About Lawn Fungus?

Lawn fungus damages grass and causes conditions such as typhula blight, rhizoctonia blight, fusarium blight and pythium blight. The key to treating lawn fungus is to identify it, then change the conditions in which it thrives.

Typhula blight, also known as snow mold, is a common lawn fungus found on Kentucky blue grass and fescue grass. It appears as gray or pink patches on the grass. It is referred to as snow mold because it is usually discovered after the snow melts. Typhula blight is prevented by mowing the lawn and applying fertilizer before the snowfall. Fungicides are used to remove tyohula blight once it has developed.

Rhizoctonia blight, also called brown patch, usually occurs in the hot weather. It produces brown circular patches 1 foot (30.48 cm) in diameter. Rhizoctonia blight is not characteristic of a specific kind of grass. Prevent rhizoctonia blight by avoiding the use of nitrogen containing fertilizer during the dry season. Fungicide is required to remove it once it has developed.

Fusarium blight, also known as pink snow mold, is characteristic of Kentucky bluegrass and can be found after the snow melt when the grass is saturated. This type of lawn fungus causes pink-colored mold to develop. Prevent fusarium from developing by avoiding the use of fertilizer in the late summer and fall and mowing the grass before the snow fall. Fungicides will not remove this type of fungus, so it must dry out on its own.

Pythium blight is found in hot, humid areas. This lawn fungus appears to be soaked in water. The water appearance is caused by the 1 to 6 inch (2.5 to 15.2 cm) wide grease slicks produced by the fungus. Strict water management is effective in controlling this fungus. Avoid overwatering in humid weather. The use of nitrogen containing fertilizer is not recommended during the dry months.

Sclerotinia dollar spot is a lawn fungus that occurs in humid areas. It is characterized by tan-colored spots that resemble cobwebs. Sclerotinia dollar spot is usually found in grass that hasn't been fertilized. Fertilizing the lawn regularly helps prevent the development of this lawn fungus. A fungicide will effectively remove it once it has developed.

Necrotic ring spot develops can develop in dry or humid areas during the spring and fall. It resembles a frog's eye due to its brown and red rings. Preventive measures include keeping the grass cut short and watering the grass in frequent, light sessions. Once necrotic ring spots have developed the grass must be reseeded.