Lawn Fungus in Jacksonville: Identify the Cause Before Treatment

Brown or thinning grass is a symptom, not a diagnosis. Moisture stress, insects, chemical injury and disease can resemble each other. Identify the cause before buying a treatment or replacing sod.

Document the problem

Photograph the whole affected area and close-up leaves, note the grass cultivar, and record when the damage started. Include recent irrigation, fertilizer, mowing and treatment changes. Check for standing water, dry coverage gaps and shaded areas. Share this history with the installer or a local UF/IFAS Extension office.

Avoid automatic treatments

Do not assume summer installation guarantees gray leaf spot, or that every patch needs preventive fungicide. A suitable treatment depends on the diagnosis, grass, product label and conditions. Do not apply more fertilizer or water to force recovery before understanding the problem.

Fairy ring is not untreatable

UF/IFAS lists fungicides that can suppress fairy ring, while explaining that reaching the fungus in the soil and managing water-repellent soil are difficult. Fungicides do not necessarily remove mushrooms or produce an immediate visible recovery. Diagnosis and soil/moisture management matter alongside any labeled treatment. UF/IFAS Fairy Rings.

Keep children and pets away from mushrooms of unknown identity; some are poisonous. Do not identify an edible mushroom from this guide.

Protect a recovering lawn

Use cultivar-appropriate mowing and avoid rutting wet ground. Follow current watering rules, correct leaks and coverage problems, and avoid persistent excess moisture. For recently laid sod, use the establishment guide before adding products.

Decide whether replacement is needed

Ask whether the turf can recover once the cause is addressed. Replacing grass without resolving shade, drainage, irrigation or disease conditions can repeat the loss. Keep any treatment plan and follow-up photographs with the job record.