Patches up to 12 inches across that develop during cold, wet weather are caused by two common diseases. Typhula Blight consists of gray-colored dead patches with tiny tan to black spherical fungal sclerotia (center). This disease develops only under snow cover, especially when soil is unfrozen. Fusarium Patch consists of pink-tinged or pink-bordered patches (right) that fade to tan as they dry. There are no fungal sclerotia, and this disease occurs with or without snow cover. Apply preventive fungicides in the fall. In spring, fluff up the matted leaves with a rake and lightly fertilize the entire lawn. Reseed spots that do not recover.