Some diseases thrive in the colder temperatures of fall and winter, even under snow. So-called "snow molds" proliferate under prolonged, deep snow, especially if the snow becomes compacted. Two common snow molds are gray snow mold (Typhula blight) and pink snow mold (Microdochium patch). Both can affect cool-season grasses in the Northeast.
Gray snow mold may form patches up to 3 feet in diameter that start brown and become gray after snow melt. The patches of pink snow mold are about 8 inches in diameter and gray to tan with pink margins.
To reduce occurrences of snow mold, avoid excessive nitrogen fertilization in the fall and don’t forget the last mowing in fall so that late top growth doesn’t mat down under snow. Avoid traffic compaction on snow-covered lawns, especially if snow is deep and on unfrozen ground. Sometimes, only foliar injury may occur and grass may grow back. If not, reseed the damaged areas when soil is thawed and drained in spring.
Shall we add some sodium chloride to this equation? Salt applied to pavement and shoveled onto your lawn during snow removal might raise your blood pressure if dead Kentucky bluegrass results this spring. Kentucky bluegrass is particularly sensitive to salt. Even if not killed, it may be weakened and prone to disease.
Calcium chloride is less damaging to turf but more expensive. If spring rains don’t occur, leach salt out of your soil by adequate watering. Tall fescue, perennial rye and fine fescue are more salt tolerant.
If you think voles are cute, you might want to keep that in mind when the snow melts. These rodents are very common locally and might have had a field day under this winter’s lasting snow cover, creating numerous runways through the turf canopy. Damage occurs from the physical traffic of their activities and from their feeding on turfgrass shoots. The good news is that they usually leave grass crowns and roots alone, but damaged areas may still require cultivation and reseeding.