Brown patch disease is one of the most common and annoying lawn diseases homeowners face. It appears suddenly and can spread quickly across turf, leaving large areas of faded grass in its wake. Lawn Doctor understands how worrying it can be to discover these ugly patches in your yard, and we’re here to help. 

What Is Brown Patch Fungus?

Brown patch fungus (sometimes called brown patch turf disease or brown patch lawn disease) is caused by a certain fungal pathogen called Rhizoctonia solani. It grows well in warm, humid conditions and can infect different types of turfgrass. 

When the fungus grows, it weakens grass blades and creates large brown rings or patches across the lawn. In severe cases, these patches join and cause plenty of damage, leaving turf looking thin, faded and unhealthy.

How to Spot Brown Patch Fungus

Although brown patch disease is one of the more common lawn problems, it can be hard to spot at first. Knowing what it is and how it spreads is the first step in protecting your yard from this harmful fungus.

• Circular or irregular patches: Brown patch fungus creates circular or oddly shaped patches that range from a few inches to several feet in diameter. Affected areas can appear tan, yellowish-brown or a shade darker than the nearby healthy grass.
• Distinctive rings: In some cases, the affected areas form rings with stronger green grass in the center. That pattern is known as a smoke ring, which happens when fungal activity concentrates on the perimeter of the patch.
• Spots on grass blades: Dark brown or gray spots with reddish-brown edges appear on individual grass blades. They can cause the blades to wither and collapse, producing a ragged look on the lawn.
• Increased damage in humid weather: Brown patch fungus usually grows in warm, moist conditions. Fast growth of patches after times of high humidity or rainfall can be a strong sign of brown patch lawn disease.

What Causes Brown Patch Fungus in Grass?

Brown patch disease grows well in places with moisture and heat. Extended periods of humidity, especially nighttime temperatures above 65 degrees Fahrenheit, create ideal conditions for fungus growth. The fungus can stay dormant in soil or thatch until conditions encourage it to grow.

• Excessive moisture: Overwatering or poor drainage keeps grass blades damp. Steady moisture is exactly what Rhizoctonia solani needs to grow.
• High humidity and warm nights: When days are hot and nights stay warm and humid, lawns may never fully dry out, which helps fungus grow.
• Thick thatch layer: A thatch layer over half an inch thick can trap moisture at the soil’s surface, and soggy conditions are a hot spot for brown patch fungus.
• Excess nitrogen: Heavy nitrogen fertilization can lead to tender grass blades that are more likely to get infected. 

Most Common Plants or Grass Types Impacted

Brown patch fungus can infect many types of turf. Certain grasses are more at risk because of where they grow or how they react to heat and moisture. Let’s look at some grasses that are prone to brown patch lawn disease:

• Tall fescue: Common in northern climates, tall fescue can struggle when late-summer heat and humidity rise. Fungus can quickly spread in these stressed spots.
• Perennial ryegrass: Perennial ryegrass does best in cooler weather. Hot, damp conditions can make it vulnerable to fungal problems like brown patch turf disease.
• Kentucky bluegrass: In regions where Kentucky bluegrass grows, warm, humid conditions can lead to several fungal issues, including brown patch disease grass problems.
• St. Augustine grass: Brown patch fungus in St. Augustine grass is a frequent issue in the South, where heat and moisture stick around for most of the year.
• Zoysia grass: Zoysia is liked for its durability and moderate upkeep, but long periods of moisture can make it prone to brown patch disease.
• Bermuda grass: Common in warm-season southern lawns, Bermuda grass is tough yet can develop brown patch fungus in hot, humid climates.
• Centipede grass: Found in southeastern states, centipede grass can face brown patch lawn fungus when moisture remains high or soil conditions are poor.

How to Treat Brown Patch Fungus

If you think brown patch fungus is in your yard, it’s important to act quickly. Mild infections might go away once the weather shifts, but moderate or severe cases of brown patch grass disease usually need brown patch disease treatment for full recovery. Here are some ideas on how to fix brown patch disease:

• Adjust your watering habits: Watering too often or late in the day keeps grass blades wet overnight. Water early in the morning so the lawn can dry by afternoon. Deep but not-too-frequent watering strengthens roots while cutting down on long-term surface moisture that fungus needs.
• Improve airflow and drainage: Good airflow around grass blades lowers fungal growth. Aerate your lawn to reduce compaction, and trim overgrown shrubs that trap humidity. Fix low spots where water tends to pool.
• Mow correctly: Keeping grass at the suggested height for its type helps it stay strong. Use a sharp mower blade to avoid stressing the lawn.
• Use fungicides when needed: Fungicide treatments can stop the spread of brown patch fungus in severe cases. Targeted brown patch fungus treatment works best when combined with good mowing and watering. Getting professional advice can help ensure safe and effective application.
• Avoid overfertilizing: Excess nitrogen produces tender growth that fungus attacks. Use a balanced fertilizer and follow recommended rates. A soil test can tell you which nutrients your lawn really needs.

How to Prevent Brown Patch Disease

By making your yard less inviting for brown patch disease, you can often keep it away. Consider the following tips:

• Schedule proper irrigation: Water deeply but not too often. That helps build strong roots and keeps grass blades from staying wet too long.
• Fertilize wisely: Balanced nutrients support healthy grass that can stand up to diseases. Pick high-quality fertilizers that suit your soil. Limit high-nitrogen applications when it’s warm and humid.
• Aerate regularly: Annual or bi-annual aeration breaks down thatch and loosens soil. That boosts water flow, lets air reach roots and encourages strong growth.
• Monitor lawn mowing height: Sticking to recommended mowing heights builds a thick lawn. Grass that’s cut too short faces stress and is more open to fungal infections such as brown patch disease.
• Inspect your lawn: Watch for early signs of brown patch in hot or humid weather. Quick detection is key to stopping the disease from spreading.

How to Get Rid of Brown Patch Fungus on Your Lawn

Brown patch disease in grass can be stubborn, but it responds well to the right brown patch lawn disease treatment and preventive steps. If your yard is dealing with brown patch lawn disease or other problems, reach out to Lawn Doctor today. Our local experts offer services that can revive your turf and keep it protected all year. We look forward to helping you enjoy a healthy, vibrant green lawn.