Snow Mold on Lawns Plant Pathology Snow Mold on Lawns Gray snow mold has been spotted on lawns already this year. Snow mold fungi work under a protective blanket of snow and make themselves known when the snow begins to melt in the spring. Circular bleached patches a few inches to a foot in diameter become obvious. These patches sometimes overlap and cause large irregular areas of browning. Problems commonly occur in years with prolonged snow cover.
Snow molds get an early start when a wet, deep snow falls on unfrozen ground.
The fall and winter weather this season was favorable for snow mold fungi. In Iowa, two different types of snow mold diseases may develop, pink snow mold and gray snow mold. The common names describe the damage they cause. When wet, the bleached patches of grass caused by the pink snow mold fungus may show a light pink fluffy growth, especially at the outer edge of the patch. Patches caused by the gray snow mold fungus tend to be covered by whitish gray strands of fungus that glue the grass blades together.