Why Do I Have Small Brown Patches in My Lawn?

Updated November 21, 2016

Brown patches appearing on the lawn may be attributed to a variety of diseases and conditions. Some diseases, like the common Rhizoctonia brown patch, may develop and spread quickly, leaving the lawn looking sickly. Fortunately, most brown patch problems can be treated and many are preventable. Understanding good lawn care practices is the best way to keep grass looking healthy and green throughout the growing season.

Brown Patch Lawn Disease

According to the Texas A&M Extension, Rhizoctonia brown patch disease is a common fungal disease causing small, round, brown patches to appear on the grass. This disease is especially common in the spring and fall. Temperatures above 21.1 degrees C cause the fungus to spread rapidly throughout the yard.

Other Causes

Rhizoctonia brown patch is not the only cause of brown patches in the grass, according to the Plant Answers website. Other common causes include drought, take-all patch disease, chinch bug infestation or grub infestation. Lawn care services and horticultural experts may help homeowners properly diagnose the conditions afflicting their lawn.


According to the University of Missouri, Rhizoctonia brown patch commonly causes round patches to appear on the ground. Other symptoms include grass appearing dried out even with sufficient watering. Doughnut-shaped patches with healthy centres are also indicative of Rhizoctonia brown patch. Brown, irregular patches in the summer may indicate take-all patch disease, another type of fungus disease.

Types of Grasses

Virtually all types of grasses are prone to brown patches caused by fungal diseases or pest infestation. According to the Texas A&M Extension, the Flora-TAM brand of St. Augustine grass is the most naturally resistant to Rhizoctonia brown patch disease, take-all patch disease and chinch bug infestations.


Homeowners can take several steps that will help prevent fungal infection, pest infestations and drought symptoms. Proper irrigation is essential to a healthy, green lawn. According to the Texas A&M Extension, grass should only be watered when necessary; overwatering can contribute to fungus production. Water to a depth of 4 to 6 inches and always water grass in the morning. Prevent thatch build-up, which may contribute to bug and fungus growth, by mowing grass frequently and removing clippings during warm, humid weather. Avoid the use of high-nitrogen fertilisers, which contribute to the prevalence of take-all and Rhizoctonia brown patch diseases.


Treat fungal diseases by regularly applying fungicides. Apply them nightly during the warm season when nighttime temperatures reach 21.1 degrees C. Stop using fungicides when the nighttime lows fall below 21.1 degrees C. According to Texas A&M, some recommended chemical fungicides are propiconazole, mancozeb, PCNB, triadimefon and myclobutanil.

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