Winter Kill and Vole Damage in Wisconsin Lawns: Diagnosis and Prevention

Analyzing Winter Patch Death

A NW Wisconsin homeowner (7-year-old lawn) had 4-18 inch dead patches after winter, plus vole trails. Some recovered after spring raking; others didn't.

Probable Causes

• Weedy grass invasion: Non-hardy grasses (e.g., annual bluegrass) invade, die in winter, leave patches.
• Snow mold (fungus): Gray/tan matted patches. Favored by late fall nitrogen, heavy snow cover, poor air exchange.
• Vole damage: Surface tunnels under snow; eat grass crowns. Recovery depends on crown survival.

Preventive Measures

• Fungicide before snow: Apply late fall (no fertilizer combo).
• Fertilize early fall: Not late fall, if snow mold history.
• Lower final mow: 2-2.5 inches reduces matting.
• Minimize winter traffic: On wet/frozen turf.
• Improve drainage: If possible.

Vole Management

• Rake damaged areas in spring—many recover if crowns intact.
• Overseed non-recovered spots.
• Reduce habitat: Mow tall grass near lawn edges in fall. Hardware cloth barriers for high-value areas.

Resources

• Snow Mold Info
• UW Extension Vole Article

Soil Testing Commendation

Testing every 4-5 years with co-op custom blend is excellent practice. Continue this.