If your lawn went into winter looking lush and green but comes out of it with gray or pink matted patches, you’re likely seeing snow mold at work. Snow mold is a common cold-weather lawn disease. It’s caused by several strains of fungi that produce long, stringy growths called mycelium – the matting that you see growing over your once-green grass blades.
The good news is that while snow mold might look bad now, it seldom kills grass. Once the weather warms and dries, the disease typically goes away, and healthy grass starts growing again.
Gray vs. pink snow mold
Lawn grasses can run into two main types of snow mold – gray snow mold and pink snow mold. Both are most active when the lawn is damp and temperatures are just above freezing
Gray snow mold is more common at the end of winters that have had extended snow cover. The matting is whitish-gray in color and often happens along driveways, sidewalks, and other areas where piled-up snow has kept the areas dark and damp the longest. Gray snow mold usually kills only the grass blades and not the underlying crowns that push out new blades once the weather warms.
Pink snow mold can form even without a snow cover and in severe cases can kill the underlying grass crowns and roots in addition to the blades. Its matting has a pink tint to it. In many cases, end-of-winter lawns have an intermingled mix of the two types.