Large Patch Fungus

Large Patch Fungus is one of the most common and damaging diseases affecting turfgrass. It is caused by a strain of the fungal pathogen Rhizoctonia solani. Large Patch thrives in extended periods of leaf wetness combined with moderate temperatures. The disease is most active in late fall and early spring, with symptoms becoming most visible during the spring green-up period.

Grasses Commonly Affected

🌱 All warm-season and cool-season grasses are susceptible to Large Patch, but some are more affected than others:

✔️ Centipede

✔️ Zoysia

✔️ St. Augustine

*Bermuda is less severely affected—its rapid growth and spread help it recover more quickly than other warm-season grasses. No turfgrass species is completely resistant to Large Patch.

Symptoms

Symptoms of Large Patch may vary between grass types and soil conditions, but common indicators include:

🔹 Thinned, light brown patches that appear in circular formations, ranging from a few inches to several feet in diameter.

🔹 Patches may merge, forming larger, irregularly shaped areas.

🔹 Infected areas may recover in the center, creating a doughnut-shaped pattern.

🔹 In severe cases, large sections of turf may thin and die without forming distinct circles.

🔹 Warm-season grasses rarely show leaf spots, but rotted leaf sheaths (where the leaf blades attach to the stem) are common near the soil surface.

Cultural / DIY Management

✅ Proper Lawn Care: Preventing Large Patch through cultural practices is easier and more cost-effective than using fungicides. However, in some cases, fungicides may be necessary for control.

🌿 Fertilization:

• Avoid high nitrogen applications in mid-to-late fall or early spring before full green-up.

• Use slow-release nitrogen rather than fast-release forms.

• All Natural State Horticare Lawn Programs are designed to prevent over-nitrification.

💧 Irrigation:

• Water only when needed—avoid both drought conditions and excessive moisture.

• Irrigate early in the morning to allow foliage to dry during the day.

• Too much moisture encourages rapid disease spread.

• Consider an Irrigation Consultation with Natural State Horticare to ensure optimal watering practices.

🚜 Mowing & Lawn Maintenance:

• Mow only when the grass is dry—avoid mowing wet grass to prevent disease spread.

• Remove clippings when warm, humid conditions persist.

• Mow at the correct height—too short weakens the grass, while too high slows leaf drying.

• Aerate the soil regularly to reduce compaction.

• Control thatch buildup to improve drainage and airflow.

🚧 Drainage & Soil Health:

• Ensure proper surface and subsurface drainage.

• Core aeration improves soil conditions and prevents excess moisture accumulation.

• Balanced soil pH enhances disease management—Natural State Horticare provides FREE pH readings with all lawn programs.