PEST BULLETIN The Snow Molds   The snow molds are caused by fungi that are adapted to grow and infect dormant plants at temperatures at or slightly below freezing.   Environmental conditions that favor snow molds include: early winter snows that fall on unfrozen soil, snow covering the turf for extended periods (2 months or more), and late winter thaws with rain and fog.   Photo 1.   Pink and Gray Snow Mold (click on image to enlarge it.) There are two main types of snow mold diseases that damage turf in the Midwest: gray snow mold caused by Typhula species and pink snow mold caused by Microdochium nivale.   Each of these diseases is favored by different turf microclimates and responds differently to labeled fungicides.   Therefore, it is necessary to examine and distinguish between the two correctly.   To compound the problem, symptoms of the two snow molds can be observed in the same turfgrass sward at the same time.   In Photo 1, the area outlined in pink contains turf affected by pink snow mold, whereas area outside the line is damaged by gray snow mold.   Click on the links to learn how to distinguish between the two and for control recommendations. Photo #1.   Gray and Pink Snow Molds in close proximity.   Pink snow mold outlined by pink line.