Grass Fungus Treatment - Learn More About Common Lawn Diseases

Two Blades Of Grass With Spots Of Fungus
leaf sop grass fungus
(Image credit: Elizabeth Bush, Virginia Polytechnic Institute,

There is nothing more frustrating than watching a well-manicured lawn fall victim to some kind of grass fungus. A lawn disease caused by a fungus of some kind can create unsightly brown patches and can kill large patches of a lawn. You can eliminate lawn fungus once you know what kind of fungus you have. Below is a description and treatment of the three most common lawn fungus problems.

Common Grass Fungus

Leaf Spot

This grass fungus is caused by Bipolaris sorokiniana. It is identified by the purple and brown spots that appear on the grass blades. If left untreated, it can travel down the blade of grass and cause the roots to rot. This will result in a thin looking lawn. Leaf spot grass fungus treatment consists of proper care of the lawn. Mow at the right height and make sure the lawn does not stay wet all the time. Water the lawn only once a week, if it has not rained in your area. Water only in the morning, so that the grass can dry out quickly. Keeping the moisture level down will allow the grass to fight the fungus and eliminate it on its own. If the grass is badly affected, you can use fungicide.

Melting Out

This grass fungus is caused by Drechslera poae. It is frequently associated with leaf spot because a lawn affected by leaf spot will be highly susceptible to melting out. This lawn disease starts out as brown spots on the grass blades that move rapidly down to the crown. Once they reach the crown, the grass will begin to die in small brown patches that will continue to grow in size as the fungus progresses. This disease commonly appears in lawns with major thatch presence. Melting out grass fungus treatment is to dethatch the lawn and apply a grass fungus spray to the lawn as soon as the disease is spotted -- the earlier, the better. Proper lawn care will help prevent this lawn disease from appearing in the first place.

Necrotic Ring Spot

This grass fungus is caused by Leptosphaeria korrae. This fungus is most likely to appear in the spring or fall. The lawn will start to get reddish brown rings and you will be able to see black “threads” on the crown of the grass. Necrotic ring spot grass fungus treatment is to dethatch the lawn vigorously. As with melting out, the thatch is how the fungus spreads. You can try adding a fungicide as well, but it will not help without dethatching regularly. Also, lower the amount of nitrogen fertilizer that you give the lawn. Even with dethatching and proper care, it may take up to two years for this lawn disease to come under control.

Heather Rhoades
Founder of Gardening Know How

Heather Rhoades founded Gardening Know How in 2007. She holds degrees from Cleveland State University and Northern Kentucky University. She is an avid gardener with a passion for community, and is a recipient of the Master Gardeners of Ohio Lifetime Achievement Award.