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Snow mold Fungal Disease

Microdochium nivale and Typhula spp.

Snow Mold is a fungal lawn disease that appears after snow melts or after long periods of cold, wet weather. It causes matted, circular patches of gray, white, pink, or straw-colored turf, especially in cool-season lawns.

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Snow mold

What Snow mold Looks Like

Snow Mold usually appears as circular or irregular patches of matted, straw-colored, gray, white, or pinkish turf after snow melts or after extended cold, wet weather.

Gray Snow Mold often has gray-white fungal growth and matted grass blades. Pink Snow Mold may have a pink, salmon, or reddish tint around the edges of the damaged area. The grass may look flattened, slimy, or stuck together when conditions are wet.

In many cases, the lawn looks worse right after snowmelt but begins to recover as the weather warms and the turf dries out.

Why It Spreads

Snow Mold develops when turf stays cold, wet, and covered for long periods. It is especially common when snow falls on unfrozen ground, when leaves or debris are left on the lawn, or when grass goes into winter too tall and matted.

The disease is often worse in shaded areas, poorly drained spots, areas with heavy thatch, and lawns that receive too much late-season nitrogen before winter. Cool-season grasses are most commonly affected.

How to Prevent It

Prevent Snow Mold by preparing the lawn properly before winter. Keep mowing until the grass stops growing, avoid leaving the lawn too tall going into winter, and remove leaves, debris, and heavy piles of clippings before snow or extended cold wet weather arrives.

Avoid heavy late-season nitrogen that pushes soft growth right before winter. Improve drainage where water sits, reduce excess thatch when needed, and rake matted areas lightly in early spring to help the turf dry out.

For lawns with a history of severe Snow Mold, preventive fungicide applications may be considered before long-term snow cover or extended cold, wet weather.

Best timing: Late fall before snow cover or extended cold, wet weather.

How to Control It

In spring, lightly rake matted areas to improve airflow and help the turf dry out. Avoid aggressive raking if the grass is still wet or weak. Once the lawn begins actively growing, apply the proper spring fertilizer to encourage recovery.

If Snow Mold is severe, recurring, or damaging high-value turf, use a fungicide labeled for Snow Mold and safe for your lawn type. Preventive applications are typically made before snow cover or before extended cold, wet conditions, not after the disease has already run its course.

Best timing: Early spring after snow melts, once the lawn is dry enough to lightly rake and begin recovery.

Recommended Solution

Snow Mold is usually managed by improving winter preparation and helping the lawn recover in spring. Start by gently raking matted areas once the turf is dry enough to work. This improves airflow, breaks up fungal growth, and helps the grass blades stand back up.

As temperatures warm and the lawn begins growing, apply a balanced spring fertilizer to help the turf recover. Most light to moderate Snow Mold damage improves with time, airflow, mowing, and proper fertility. If the same areas are damaged every year, focus on fall cleanup, proper mowing height before winter, drainage improvements, thatch reduction, and preventive fungicide timing before winter weather begins.

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Frequently Asked Questions

What causes Snow Mold in lawns?

Snow Mold is caused by fungi that develop during cold, wet conditions, especially when turf is covered by snow, leaves, or debris for long periods. It is often worse when grass goes into winter too tall, matted, or overly lush from late-season nitrogen.

What does Snow Mold look like?

Snow Mold usually appears as matted circular patches of gray, white, pink, or straw-colored grass after snow melts. Some patches may have fuzzy fungal growth, while others may look flattened, slimy, or bleached.

Will Snow Mold go away on its own?

Light to moderate Snow Mold often improves as the lawn dries out and begins growing in spring. Light raking, proper mowing, and spring fertilization can help the lawn recover faster. Severe or recurring areas may need preventive fall treatment.