CSLB C-27 Landscaping ContractorPlanting and LandscapingHard
A homeowner reports that their lawn has developed circular patches of brown, dying grass, especially noticeable in hot, humid weather. The patches are expanding, and a close inspection reveals a distinct 'smoke ring' of darker, healthier-looking grass around the perimeter of the brown areas. Which turfgrass disease is most likely causing this pattern?
- ADollar Spot
- BRust
- CPythium Blight
- DBrown Patch
Show answer & explanationAnswer & explanation
Correct answer: D. Brown Patch
Brown Patch is a common fungal disease of turfgrass, particularly active in hot, humid conditions. It typically presents as circular patches of brown, thinning grass, often with a distinctive dark, water-soaked, or 'smoke ring' margin of discolored grass, especially in the early morning when dew is present.
Why the other options are wrong
- A. Dollar Spot causes small, straw-colored spots (dollar-sized) that may merge, but typically lacks the distinct 'smoke ring' and generally isn't described as rapidly expanding large patches.
- B. Rust appears as orange or yellowish-brown pustules on grass blades, causing a dusty appearance, not distinct circular brown patches with a 'smoke ring'.
- C. Pythium Blight causes greasy, water-soaked spots that quickly turn brown, often in streaks or irregular patches, and has a characteristic 'cottony' fungal growth, not a 'smoke ring' appearance.
Brown Patch Disease
A common fungal disease of turfgrass, creating circular brown patches, often with a characteristic dark 'smoke ring' margin, favored by hot, humid conditions.
- Circular brown patches.
- Distinct 'smoke ring' margin.
- Favored by hot, humid weather.
- Caused by Rhizoctonia solani.
Memory trick: Brown 'Rings' with 'Smoke' mean 'Brown Patch' is the culprit.