What is a common turf disease characterized by circular patches and warm, humid conditions?

• A. Brown patch
• B. Dollar spot
• C. Pythium blight
• D. Rust

Answer: (A)

Brown patch shows up as circular patches of dead turf under warm, humid conditions. This disease is caused by Rhizoctonia solani and thrives when temperatures are in the 75–85°F range with frequent leaf wetness from dew or irrigation. The patches typically begin as tan to brown areas and grow into round or irregular circular shapes that can merge with neighboring patches, which is a hallmark you’d notice in warm, humid weather.

Understanding the other options helps confirm why this is the best match. Dollar spot creates small, silver-dollar–size patches and is more common in hot, dry, sunny conditions and lighter, sandy soils. Pythium blight produces rapidly spreading, greasy-looking patches in very wet, hot conditions. Rust appears as a powdery orange to yellow spore coating on leaves rather than distinct circular patches.

Management focuses on reducing leaf wetness and improving air movement: adjust irrigation to avoid prolonged leaf wetness, improve drainage, mow at proper heights, and use appropriate fungicides when needed.