Dollar Spot / • Brown Patch / • Red Thread / • Gray Leaf Spot
Q: What causes these diseases?
Dollar Spot: Caused by the fungus Sclerotinia homoeocarpa, and thrives in warm, humid weather with high nitrogen deficiency.
Brown Patch: Caused by Rhizoctonia solani, it thrives in hot, humid weather and over-fertilized, overwatered lawns.
Red Thread: Caused by Laetisaria fuciformis, it often affects turf with low nitrogen during cool, damp periods.
Gray Leaf Spot: Caused primarily by Magnaporthe grisea, it thrives in warm, humid conditions and spreads through wind, rain splash, and contaminated tools or equipment.
Q: How can I identify these diseases?
Dollar Spot:
- Small circular patches (1–2 inches).
- Leaf lesions with tan centers and reddish-brown borders.
- Webby white mycelium in early mornings.
Brown Patch:
- Circular brown patches (6 inches to several feet).
- Grayish “smoke ring” in early morning dew.
- Affected grass blades have lesions with tan centers.
Red Thread:
- Pink to red “threads” on grass blades.
- Irregular patches, 4–8 inches.
- Affected leaves are water-soaked and pinkish.
Gray Leaf Spot:
- Leaf spots: Small, round to oval lesions with gray centers and dark brown to purple borders.
- “Melting out”: Affected blades may wither and die, causing thinning or bare patches.
- Appearance: Disease often begins in shaded, humid areas and can spread quickly.
Fungicide Treatments for Lawn Diseases
1. When to Use Fungicides – To effectively treat and prevent lawn diseases, fungicide treatments can play a key role.
- Curative: When disease symptoms are already visible.
- Preventive: Before symptoms appear, especially during high-risk conditions (e.g., high humidity, warm temps, poor airflow).
Pro Tip: Prevention is often more effective and less expensive than curing an active outbreak.
