Plan the perfect garden with our interactive tool →

Types of Lawn Fungus

grass image by Marek Kosmal from

Lawn grass diseases are overwhelming and stem from invasive, harmful fungi. Fungi are microorganisms that live in soil, on dead organic material or on living plants and animals. Many types of lawn fungus are benign; however, certain types of lawn fungus can cause unsightly discoloration that eventually can lead to grass death. The best way to prevent fungal diseases is to properly care for your lawn with the correct amount of water and fertilizer. If a lawn disease does develop, fungicides are an effective method of removal.

Brown Patch

Brown patch disease begins as a small, brown patch that expands outward in a horseshoe or circular pattern. As it spreads, the area inside the ring can sometimes recover from the disease, leaving the area with what looks like a smoke ring. This fungal disease is common in Bermuda, St. Augustine, rye, centipede and Kentucky bluegrass. The best preventative measures include aerating often and reducing shady lawn areas. Effective fungicides for brown patch include benomyl and chlorothalonil.


Snowmold can occur on lawns with standing amounts of snow during the winter months and appears as a brown, mold color on the grass blades. Snowmold is most commonly found in fescue and Kentucky bluegrass, and it is preventable with adequate amounts of aerating and fertilizing during the spring and fall months. Benomyl is the most common fungicide for treatment of snowmold.


Rust disease is commonly found on rye and Kentucky bluegrass and is identified by an orange, rusty color on the grass leaves. It spreads in shady areas and in places where there is morning dew, low fertility or high soil compaction. Mowing, aerating, watering and fertilizing at the correct amount and interval will help to prevent rust fungal disease. Anilazine and triadimefon are the most common fungicides for the treatment of rust.

Dollar Spot

Dollar spot fungal disease is identified by small, circular and brown or straw-colored discolorations that can grow into areas several feet wide. This fungus is found most commonly in bent, Bermuda and Kentucky bluegrass; dollar spot is also found in humid climates and is preventable with regular aeration and morning watering. Thiophanate, anilazine and benomyl are the best fungicide chemicals to use to remove dollar spot.

Grease Spot

Grease spot lawn disease can affect all warm- and cool-season grasses in humid climates. This fungus, which can grow in streak-like patches across a lawn, is identified by brown spots with a greasy, slimy texture and a white, cottonlike fungus visible on the grass blades. Proper aeration and reduced shade will aid in the prevention of grease spot. Metalaxyl is the best fungicide chemical for the problem.

Garden Guides