These fungi thrive when moisture is plentiful and when prolonged periods of snow cover exist, especially after the snow falls on unfrozen ground. Gray snow mold has been common on Iowa lawns and golf courses this month. Symptoms of this disease become evident as the snow melts. The leaves in the affected areas are matted together and have a silver-gray, crusted appearance as the grass dries.
Affected areas vary from several inches to a few feet across.
Larger diseased areas may occur if the affected areas coalesce. They appear as match-head size or smaller structures, brick red to brown in color, and are embedded in leaf tissue. A magnifying glass or dissecting microscope is useful when looking for these structures. Control Many times the injury from light attacks of gray snow mold disappear with higher temperatures and spring growing conditions. In severe cases, however, the grass dies and overseeding will be necessary.