Fusarium Patch (Microdochium nivale), Fusariumpatch is a fungal disease that attacks lawns. Infection occurs most often at temperatures between 32° and 50°F, conditions which are present under snow, therefore giving it the common name of snow mold. However, snow cover is not required under conditions of extended leaf wetness. Severe outbreaks can occur at 65°F anytime of the year in some regions. Symptoms appear later as irregular patches of yellow then brown grass up to 30 cm in diameter when there is high humidity and temperatures of up to 65°F. This usually occurs between May and September. When damp conditions prevail, the dead blades of grass become slimy and are covered in a light pink bloom.