Problem: Fusarium Patch
A plant disease that primarily affects cold-season grasses, fusarium patch (also known as pink snow mold) is caused by the fungus Microdochium nivale. Active only at cold temperatures (32° to 60°F) when moisture is abundant, fusarium patch is most likely to occur after snow has been on the ground for several months. Prolonged cold weather worsens symptoms; turf quickly recovers if warm weather follows the melting of snow. Prolonged rainy periods in winter also favor this disease. Serious infection leads to crown and root rot.
Reduce shade in infected areas. Do not apply excessive nitrogen-rich fertilizer in the fall. Overly tall grass is susceptible to fusarium patch, so mow lawn in autumn before snowfall. Reduce thatch buildup. Lightly infected turf usually recovers on its own.