What Is Brown Patch Fungus?

Brown patch fungus, caused by Rhizoctonia Solani, is a common lawn disease that affects various grass species in Bradenton and Sarasota Florida, including the popular St. Augustine grass and is a soil-borne pathogen that thrives in warm, moist environments. It typically becomes active in the fall and winter when temperatures range between 65°F and 85°F, combined with high humidity. This disease is known for creating large, circular, or irregular patches of dead or discolored grass. Infected areas may initially appear yellow or light brown before turning darker as the fungus spreads.

Early detection of brown patch fungus is crucial for effective management. Key signs include:

• Discolored Patches: Circular or irregular patches of yellow, brown, or tan grass that can be several feet in diameter.

• Leaf Lesions: Dark, irregular spots or lesions on grass blades.

• Soft, Rotting Grass: The affected grass may feel slimy or soft near the base, especially in humid conditions.

• Distinct Outer Ring: In some cases, a smoke-ring effect—a dark, thin ring around the patch—may be visible in the early morning due to moisture.

Why Does Brown Patch Fungus Develop?

Several factors contribute to the development of brown patch fungus:

1. Excess Moisture: Overwatering or poor drainage creates the perfect environment for fungal growth.

2. High Humidity: Florida’s naturally humid climate increases the risk.

3. Improper Fertilization: Excess nitrogen fertilization encourages lush, tender growth that is more susceptible to infection.

4. Warm Temperatures: The disease thrives when temperatures are between 65°F and 85°F.

5. Shaded Areas: Lawns in shaded areas are more likely to develop the fungus due to reduced air circulation and prolonged moisture retention.

Native Florida Grasses Affected

While St. Augustine grass is particularly vulnerable to brown patch fungus, other native Florida grasses such as zoysia and Bahia can also be affected. However, St. Augustine’s dense, lush growth makes it more prone to fungal diseases under poor maintenance conditions.

Westfall's Recommended Prevention Strategies

Preventing brown patch fungus is more effective than treating it. Here are some best practices:

• Water Wisely: Avoid overwatering. Water early in the morning to allow the grass to dry throughout the day. Aim for 1 inch of water per week, including rainfall.

• Improve Drainage: Ensure proper drainage to prevent water accumulation in low areas.

• Mow Correctly: Keep grass at the recommended height for the specific variety. For St. Augustine, maintain a height of 3 to 4 inches. Avoid cutting more than one-third of the blade length at a time.

• Balanced Fertilization: Use a balanced fertilizer with controlled-release nitrogen. Avoid applying high-nitrogen fertilizers during the disease-prone fall months.

• Promote Airflow: Thin out thick vegetation around shaded areas to improve airflow and reduce moisture retention.

Treatment Options

If brown patch fungus has already appeared, quick action can help minimize damage:

• Fungicide Application: Apply a fungicide labeled for brown patch control, such as products containing azoxystrobin, propiconazole, or thiophanate-methyl. Follow label instructions carefully.

• Cultural Adjustments: Reduce watering and avoid fertilization until the disease is under control.

• Proper Cleanup: Remove and dispose of infected grass clippings to prevent the spread of fungal spores.

Long-Term Lawn Health

Maintaining a resilient lawn involves consistent care and monitoring. Here are additional tips to ensure long-term health:

• Soil Testing: Conduct regular soil tests to determine nutrient levels and pH balance.

• Aeration: Aerate compacted soil to improve drainage and reduce fungal risk.

• Seasonal Maintenance: Adjust lawn care practices based on seasonal conditions to reduce stress on grass.

Conclusion

Brown patch fungus can be a persistent problem for Florida homeowners in Bradenton and Sarasota, particularly those with St. Augustine and other native grasses. However, with proper cultural practices and timely intervention, this disease can be managed effectively. By adopting preventive measures, practicing responsible lawn care, and staying vigilant, you can maintain a healthy, beautiful lawn year-round.

-The Westfall Team