Pink Snow Mold

The correct name for the disease many know as pink snow mold or Fusarium patch is now Microdochium patch. Over the years, the fungus which causes this disease (now called Microdochium nivale) has been reclassified and renamed many times. Pink snow mold is common and troublesome where prolonged periods of wet, cool weather occur during winter and spring. The disease often occurs in the absence of snow and is favored by cool or cold wet weather when grass growth is slow. Disease development occurs rapidly when humidity is high and temperatures are 32 to 46 F with a maximum of about 55 F. The disease first appears as round, water-soaked spots, 1 to 3 inches in diameter, that soon turn into yellow, orange-brown, or reddish brown patches. Patches may enlarge and become light gray or light tan rings. Under snow cover or with very wet conditions, varying amounts of white fungal growth may be seen on matted leaves. Where there is snow cover, the disease may blight large areas. As the snow melts, the white fungal growth at the perimeter of the patch turns pink; hence the name "pink snow mold".