Here in the Hendersonville and Asheville areas, Brown patch is a common lawn fungus triggered by high heat, humidity, and extended leaf wetness. The combination of late afternoon thunderstorms followed by a humid nights makes our cool season grasses ripe for this fungus during the summer.
Why Brown Patch Happens
- The fungus becomes most active when the combined air temperature and relative humidity equal 150 or higher, particularly when nighttime temperatures stay above 65°F to 70°F. We often refer to this as the 150 degree rule.
- Excess Nitrogen Fertilization: Fast-release nitrogen pushes lush, succulent growth, which is highly susceptible to fungal infection.
- Moisture & Shade: Standing water, lack of air movement, and grass staying continuously wet for 10 or more hours create the perfect breeding ground for the fungus to grow.
How to Avoid Brown Patch
- Water in the Morning: Only irrigate early in the morning (between 4 AM and 8 AM) so the morning sun can dry the grass blades. Never water in the late afternoon or evening. Unfortunately, Brown Patch is often confused with dryness, leading the unwary homeowner to only make the condition worse.
- Adjust Your Mowing: Mow cool-season grasses (like Tall Fescue) to the optimal height of about 4 inches Mowing too short stresses the grass, while cutting too high traps moisture. If the disease is active, bag your clippings to avoid spreading spores.
- Limit Summer Nitrogen: Avoid high-nitrogen fertilizers during the summer months. Instead, focus on slow-release fertilizers during the cooler fall months for cool-season grasses.
- Improve Drainage & Airflow: Aerate your lawn annually to reduce soil compaction. Trim back overgrown shrubs, bushes, and low-hanging tree branches to increase sunlight and improve air circulation over your turf.
- Apply Preventative Fungicide: If you know your lawn is prone to brown patch during hot/wet stretches, apply a preventative fungicide (like those containing azoxystrobin or pyraclostrobin) before the disease window opens in late spring or early summer.
And if this sounds like a lot of work, don’t worry. Call us to schedule an appointment and one of our lawn care professionals can give you a no obligation quote for making your lawn the envy of the neighborhood.