Brown patch: what it is, and what to do about it.

If circular brown patches have shown up in your lawn during a hot, humid stretch, there's a good chance you're looking at brown patch, a common fungal disease in North Texas yards, and one that spreads quickly if it's ignored.

What causes it

Brown patch is caused by a fungus called Rhizoctonia solani, which thrives in hot, humid conditions. Overwatering, poor soil drainage, and a heavy thatch layer create the ideal environment for it to take hold. Low mowing height, poor soil fertility, and heavy foot traffic can all make a lawn more susceptible.

How to recognize it

Look for roughly circular brown patches, anywhere from a few inches to several feet across. The edges often look yellow or reddish, and affected grass can appear slimy or greasy when wet. Left untreated, the grass inside the patch can die off entirely, leaving bare spots.

Brown patch spreads through moisture. Every watering habit that keeps grass wet overnight gives it more room to grow.

Prevention beats treatment

• Water deeply and infrequently, and avoid watering in the evening or overnight.
• Avoid over-fertilizing, especially with fast-release nitrogen during hot, humid stretches.
• Mow at the correct height for your grass type, scalping stresses the lawn and opens the door to disease.
• Keep thatch under control with regular aeration.

If it's already there

An affected lawn may need a fungicide application to stop the spread, along with aeration and dethatching to improve airflow at the soil surface. Adjusting your watering and fertilizing habits at the same time helps prevent it from coming right back.