Brown Patch Diagnosis: Is It Disease or Environment?

Brown patches in your lawn – is it brown patch disease or something else? Answer matters: disease needs fungicide; environmental causes waste money on chemicals.

Disease vs. Environment

Brown patch causes dead patches, but so do:

• Poor drainage (water >24 hours → root rot)
• New sod (<1 year) on unplowed, compacted soil → poor rooting → brown patches in dry weather
• Former high-traffic areas (home plate, goalie zone) → soil hard as concrete

True Brown Patch Symptoms

• Start small, enlarge rapidly in warm weather.
• From above: doughnut shape – tan ring with green center.
• Individual blades brown to crown (where blade emerges), but crown stays green.
• Early morning in hot, damp weather: white fungal web at patch edge.

Keep Grass Healthy

Fungus is always present. Grass gets sick when weak. Fertilize only when needed: cool months for fescue, warm months for bermuda.

Watering

• Never water in evening.
• Best: early morning.
• Fescue susceptible with lush growth + warm nights.
• Water after dew dries in morning. Alternative: water after nightfall (grass already wet with dew, doesn't extend wet period).
• Brown patch needs 14–16 hours wet leaf surface to reproduce.

Fertilizer

Late spring/summer N causes rapid growth (more mowing!) and drought stress. Fertilize fescue only fall/winter/spring. Dr. Lee Burpee (Griffin): June–August N increased brown patch severity on all cultivars except Kentucky 31. Worse at mowing heights <2 inches and >3 inches. Fungicides available but must be applied regularly. Change culture first.

Fungicides

If certain it's brown patch, several fungicides work. But cost may deter: ~$20/1,000 sq ft/application. 5,000 sq ft lawn = $100 every 2 weeks. Let pocketbook guide you!

Positive Identification

Get positive ID from local Extension (1-800-ASKUGA1). Bring 4×4 inch sample (half dead/half live, include roots) from disease margin. Don't let sample heat/dry. Paper bag or unsealed plastic. Refrigerate if not same-day. Submit Mon/Tue for lab mailing. Results ~10 days.

Lawn Disease ID Sampling – Critical for accurate diagnosis.