Prolonged snow coverage leads to areas of snow mold

Winter snowfall is beginning to melt and the artic air that gripped the eastern two-thirds of the country has retreated.

However, this temperatures shift and rapid thawing has lead to an unwelcome sight across many lawns: snow mold.

Prolonged snow coverage

A snow event on Jan. 24 to 26 brought snow and ice to regions of the Midwest, Mid-Atlantic and Southeast. Following the winter weather, arctic air surged south, keeping much of the region snow- and ice-covered.

Another system Jan. 31 to Feb. 2 brought snow to the Mid-Atlantic, with areas like Charlotte, N.C. picking up just under a foot of snow. Like its predecessor, this storm was followed by bitter cold, leaving snow-covered ground in areas that don’t see flakes every winter.

Snow mold

If you start to notice odd circular patches or web‑like areas on your lawn, with pink or grayish discoloration, you might have snow mold. 

According to Cardinal Lawn’s Lawn Disease Library, snow mold or snow rot is a type of fungal lawn disease that forms from sustained snow cover or wet leaves. It is most visible in spring after snow melts, but sometimes it is observed in winter after a big snowfall and then a thaw.

Any grass exposed to cold temperatures and snow cover can be affected, and if left untreated, the lawn may suffer damage. 

This fungus thrives in cold, damp conditions, damaging individual blades as well as the crown and roots. It often appears as gray circular patches or pink, web‑like growth. The pink type is the more severe fungus and does not need snow cover, as it proliferates when the grass is wet and temperatures are below 45 F.

While most lawn diseases are associated with warm weather, TruGreen’s lawn care tips note that snow mold only occurs on actively growing winter grass in cooler weather and can persist up to 60°F if air and soil remain moist. Spores can be spread by wind or splashing rain, moving the disease from one part of the lawn to another.

Prevention

Although it’s impossible to completely prevent, some fall planning might help keep it at bay. TruGreen recommends mowing your lawn short before the grass goes dormant, 2 to 2.5 inches. Shorter grass is less likely to mat down.

It’s best to avoid nitrogen fertilizer in late fall and make sure your soil drains properly to prevent excess moisture. Late summer or fall aeration can help break up the plant material that exists between the soil and the grass. 

During the winter, don’t let the snow pile up. Those large piles that were created from clearing driveways and sidewalks need to be spread out and shortened. Any piles that take long to melt could be potential breeding grounds for the fungus.

Repair

Snow mold may happen despite best efforts. Ways to treat it include raking the matted grass, which adds circulation and helps to stimulate new grass growth. If your grass still doesn’t appear healthy, consult a lawn care company.

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