Brown patch is a fungal disease that creates circular brown or tan patches in lawns, primarily affecting fescue and other cool-season grasses during hot, humid Oklahoma summers. The patches can range from a few inches to several feet across and often have a distinctive darker “smoke ring” border when active. To prevent brown patch, avoid evening watering, improve air circulation, don’t over-fertilize with nitrogen in summer, and mow at proper heights. Complete Lawn Care can diagnose lawn diseases and recommend treatment options.
What Is Brown Patch Disease?
Brown patch is caused by the fungus Rhizoctonia solani, which lives in the soil and becomes active when conditions are right: warm temperatures (75-90°F), high humidity, wet grass blades, and stressed turf. It’s one of the most common lawn diseases in Oklahoma, especially in fescue lawns.
The fungus attacks grass blades at the soil line, causing them to rot. Affected grass pulls out easily because the connection between blade and root is damaged. Unlike many other lawn problems, brown patch can spread rapidly, sometimes overnight under ideal conditions.
How to Identify Brown Patch
Circular patches: The most distinctive sign. Patches are roughly circular and can range from a few inches to several feet in diameter.
Smoke ring border: When actively spreading, you may see a darker, water-soaked-looking ring at the edge of the patch, usually visible in the early morning. This is the advancing edge of the infection.
Tan or brown grass: Affected grass turns tan to brown. Unlike drought stress (which looks similar), brown patch often has green grass remaining in the center of patches.
Easy pull test: Infected grass blades pull out easily at the base. You may see rotting at the soil line where the fungus attacked.
Timing: Brown patch typically appears in Oklahoma from late May through September when temperatures and humidity are high.
Conditions That Cause Brown Patch
Wet grass overnight: The fungus needs moisture on grass blades to infect. Evening watering or heavy dew that doesn’t dry provides ideal conditions.
High humidity: Oklahoma summers are often humid, especially after rain. Combined with warm nights, this creates prime brown patch weather.
Excess nitrogen: Too much nitrogen fertilizer creates lush, tender growth that’s more susceptible to fungal attack. Avoid heavy nitrogen applications in summer.
Poor air circulation: Lawns surrounded by fences, buildings, or dense landscaping don’t dry as quickly, keeping conditions favorable for fungus.
Stressed grass: Grass that’s already stressed by heat, drought, or improper care is more susceptible to disease.
How to Treat Brown Patch
Cultural controls (first line of defense):
Stop evening watering immediately. Water only in the early morning so the grass can dry during the day. Reduce watering frequency if possible (but don’t let grass drought-stress). Improve air circulation by pruning nearby shrubs or thinning tree canopies. Avoid fertilizing until conditions improve.
Fungicide treatment:
If cultural controls aren’t enough, fungicides can help. Products containing azoxystrobin, propiconazole, or myclobutanil are effective against brown patch. For best results, apply preventively before symptoms appear if you have a history of brown patch, or at the first sign of infection. Follow label directions carefully.
How to Prevent Brown Patch
Water in early morning only: This is the single most important prevention step. Grass should be dry by evening.
Avoid excess nitrogen in summer: Back off fertilization during hot, humid weather, especially for fescue.
Mow at proper height: Keep Fescue tall (3-4 inches). Don’t scalp the lawn, which stresses grass and makes it more susceptible.
Improve drainage: Address low spots where water collects. Aeration helps water penetrate rather than sit on the surface.
Reduce thatch: Heavy thatch holds moisture against grass blades. Regular aeration helps manage thatch.
Will My Lawn Recover?
Usually, yes. Brown patch typically damages grass blades but not roots. When conditions improve (cooler, drier weather), affected areas often recover on their own. Bermuda fills in quickly; fescue may need overseeding in fall to fully recover. Severe or repeated infections can eventually kill grass, making prevention important.
Complete Lawn Care Can Help
If you’re seeing circular brown patches in your lawn, contact Complete Lawn Care for diagnosis. Not all brown patches are brown patch disease. It could be grubs, drought, chemical damage, or other issues. We can identify the problem and recommend the right treatment. Our 7-step program builds overall lawn health, which helps prevent disease problems.
Contact Complete Lawn. Care:
Phone: (918) 605-4646 | Email: [email protected] | Online: completelawncaretulsa.com/get-a-quote