What are typical signs of brown patch on cool-season turf?

• A. Localized circular patches with tan to brown centers, darker margins, and occasional wilting under humid, warm conditions.
• B. Uniform yellowing across the entire lawn.
• C. Broad, irregular necrotic patches with blackened leaf tips.
• D. Patches with gray-white powdery appearance.

Answer: (A)

Localized circular patches with tan to brown centers and darker margins are classic signs of brown patch on cool-season turf. This disease thrives in warm, humid conditions, and leaves within the patch may wilt or collapse when humidity is high, giving that crisp edge between healthy turf and diseased areas. Patches often start small and can expand or merge under sustained warm, wet or humid weather.

The other descriptions don’t fit brown patch: uniform yellowing across the entire lawn points to drought stress or nutrient deficiency rather than a focal fungal patch; broad irregular necrotic patches with blackened leaf tips suggest a different pathogen or stress; patches with a gray-white powdery appearance are more typical of powdery mildew or similar diseases. If you suspect brown patch, look for warm temperatures with leaf wetness and high humidity, and manage with cultural practices (reduce irrigation, avoid excess nitrogen, improve air circulation) and, if needed, fungicide programs.