Snow mold

Typhula blight

Snow molds are caused by cold tolerant fungi that require snow cover or prolonged periods of cold, wet conditions. Typhula blight is most notably found in the turf industry, effecting a wide range of turfgrasses. Upon the snow melt, gray circular patches of mycelium are found. These mycelia produce a survival structure called a sclerotia that survives the warm summer months.


Typhula blight is a major problem with cool season turfgrasses during winter months. These grasses include bentgrass, annual bluegrass, perennial ryegrass, fine fescue, and kentucky bluegrass. Typhula blight is also commonly referred to as gray snow mold due to the gray colored patches found after snow has melted. Gray snow mold effects all of its hosts in the same way. After the snow has melted, gray to grayish white patches of mycelium, six to twelve inches in diameter, can be found. Within the patches, diseased grass blades often reveal either rusty or reddish brown colored sclerotia up to five millimeters in diameter. Gray snow mold can cause thinning and possibly death of the infected host.

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