Identifying and Managing Lawn Rust Disease in Michigan

Symptoms

Orange-yellow powder on grass blades, shoes, and mower = rust fungus. Common on Kentucky bluegrass, ryegrass, fescue in late summer/fall.

Causes

• Low nitrogen (slow growth).
• Drought stress or excess rain leaching nitrogen.
• Cool nights, heavy dew, light rain.
• Warm, cloudy, humid weather followed by hot sun.

Cultural Control

• Water early morning so grass dries quickly.
• Apply early fall nitrogen (but don't overdo).
• Winter fertilizer around Thanksgiving.
• Prune for airflow and light.
• Manage thatch.

Fungicides rarely work on home lawns for rust. Improved growth in early fall usually outpaces the disease.