You Are Here: Management Updates 2004 Archive March 22, 2004

Date: March 22, 2004
Category: Diseases
Subject: Snow Mold After Snow Melt

There are two important snow molds in most of New England, Fusarium patch (pink snow mold) and Typhula blight (gray snow mold).

Typula blight (Typhula incarnata in most areas) can be identified by the grayish white mold (mycelium) that is usually easily observed at the leading edge of the 6-12" patches when they are still moist after snow melt. It usually disappears quickly as the patch dries although the mycelium and dead leaf blades will remain matted. Look also for the seedlike reddish brown sclerotia in the matted tissue. In northern New England, another species of this fungus that produces numerous smaller black sclerotia may also be present (Typhula ishikariensis).

Typhula blight is the snow mold that is most common in lawns, athletic fields, and other higher cut turf. It is no longer active after snow melt, so no fungicide should be applied in the spring. Rake away the matted tissue and overseed any thin areas after the grass begins to grow. Damage is usually minimal even though it can look terrible when the snow first reveals the patches which can coalesce until most of the turf area looks affected..

Fusarium patch (Microdochium nivale) is common on golf course putting greens. It is often seen in areas of poor drainage or around the shaded side of the green. The pink color is most common after snow melt at the leading edge of the patches that tend to be 3-6" in diameter. Unlike Typhula blight, this disease can remain active until warm, dry weather occurs. We have had samples in the diagnostic lab as late as June 20. During the early spring, new patches will look greasy rather than pink, similar to Pythium blight in the hot summer. It may look as if someone dripped hydraulic oil across a patch of turf.

The fungus produces numerous spores that are easily spread by water and mowers, so allowing the green to dry before mowing will reduce spread. Lush growth is more susceptible, so hold off on N fertilizers if the disease is active. If cool, wet weather persists, spot treatment of affected areas with fungicides is recommended. The DMI fungicides seem to work best for preventive sprays. Iprodione is often effective and inexpensive.

- Submitted by: Dr. Gail Schumann