Gray snow mold, Typhula spp on lawn

Disease Information

Gray snow mold, Typhula spp


Symptoms and damage

Gray snow mold is a common cold-weather disease  that can affect all cool-season turfgrass. It typically attacks turfgrass leaves but can kill the crown during a severe outbreak. Loss of the meristematic tissue (turfgrass crown) will cause plant death. It develops during winter under snow cover at temperatures just above freezing, usually requiring

30-plus days for development.

After the snow melts from an infected area, light tan patches ranging from 2 inches to 2 feet are present in the lawn. Patches also may coalesce under snow cover to produce a larger infected area. The disease

cannot advance once snow cover recedes. The patches often are covered by a white, cottony growth called mycelium. Thirty days of snow cover can result in a light outbreak. Sixty days of snow cover typically

results in a moderate outbreak and 90-plus days of  snow cover can cause a severe outbreak. If the crown is killed, the turf must be re-established.

COMMENTS on disease

Fungi survive warm weather as resting structures called sclerotia, which are black (T. ishikariensis) or reddish brown (T. incarnata) structures visible to the naked eye. They may resemble black pepper sprinkled

over leaves and ground litter or they may grow as large as a pin head either on or embedded in the grass leaves.


A preventative fungicide treatment applied right before permanent snow cover occurs usually is very effective in preventing gray snow mold infection

Chemical control

 Instrata (chlorothalonil,

fludioxonil and propiconazole), Bayleton (triadimefon),

Prostar (flutolanil) and Medallion (fludioxanil).

Susceptible Turfgrass Species:

Moderate Susceptibility

Kentucky bluegrass

Perennial ryegrass

Fine fescues

Tall fescue

Severe Susceptibility

Annual bluegrass


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