Grass Fungus: How to Spot It, How It Grows, and Treatment

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Have you started noticing round, discolored patches in your lawn? You may have grass fungus. 

Grass fungus can be ugly, but it doesn’t have to destroy your lawn. 

 First, it’s important learn how to identify grass fungus. Then, find out about treatment for grass fungus and how to prevent fungus from coming back. 

Fall Grass Fungus in Florida 

Fungi are the main cause of disease in Florida turfgrass. If you have lawn fungus in the fall, it’s likely to be brown patch fungus. This type of fungus is also called large patch or rhizoctonia blight. Brown patch affects the blades of grass. It doesn’t harm the crown of the plant or the roots. 

Cooler weather combined with humidity and high moisture content in the soil provides ideal conditions for brown patch. Brown patch usually starts appearing in mid-October. It will disappear once the weather gets too warm, which usually happens near the end of April. 

Brown patch fungus affects all warm-season turfgrasses, including zoysia grass and St. Augustine grass. 

How to Recognize Brown Patch Fungus 

Brown patch looks like round, discolored patches in the lawn that get larger over time. These circles range in size from 6 inches to several feet in diameter. The edges of the patches can be orange. The center is brown and can look sunken. 

 The ring is usually less than an inch wide, and it’s most visible in the morning.The grass within the ring will sometimes die entirely, but more commonly it just gets thinner. 

Conditions that Contribute to Brown Patch Fungus Growth 

Brown patch fungus stays in the grass or soil during the winter. It can survive for years waiting for the right conditions. 

 In addition to humidity and favorable temperatures, too much nitrogen and water are the main factors contributing to the appearance of brown patch. Poor soil drainage, a build-up of thatch, and compacted soil are other factors that favor brown patch fungus. 

Controlling and Preventing Brown Patch Fungus 

Stopping fungus from growing is easier than trying to get rid of it later. You can take several steps to prevent brown patch from taking hold in your lawn. These measures will also help to control an outbreak if it has already started. 


Water your grass early in the morning. The lawn can dry during the day, which helps prevent fungus. Be sure not to overwater. 

H2: Mowing 

Sharpen the blades on your lawnmower. Dull mower blades tear off the grass instead of cutting it cleanly. Torn blades of grass develop fungus more easily. 

You should cut no more than a third of the grass height at a time. Cutting the grass too short weakens it. Stressed grass has a greater risk of developing fungus. 

 Mow any affected parts of your lawn last. Wash the underside of the mower to avoid spreading fungus. 


Using too much or too little fertilizer makes the grass more likely to have a fungal disease. Choose a fertilizer for the type of grass you have. Be sure you apply only as much as the manufacturer recommends. 

Air Circulation 

Improving the air circulation in your lawn reduces humidity. Aerate and dethatch the lawn yearly to help the soil breathe. 

Treatment for Grass Fungus 

Even after adjusting your lawn care practices to control and prevent brown patch, you may need a fungicide to fully get rid of it. You can do it yourself, but a professional lawn care company is better equipped for the job. 

 A lawn care specialist will ensure that your grass gets the right product with the correct application. You get better results. It’s safer for you and for the environment. 

 One Two Tree will treat your grass fungus and prevent it from coming back. Check out our lawn care services and contact us for a free quote.

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