This winter brought very little snow and it is likely snow mold in home lawns will not be a problem. With that said, small areas of the disease may be observed in areas of the lawn that collected snow drifts. Snow mold is usually observed as grey, pink, or straw colored patches in the lawn. Grass within these patches often has a matted appearance with mycelium (thread like fungal structures) bordering or completely covering the area.

The two most common types of snow mold fungi are gray and pink. Gray snow mold is caused by Typhula spp. and produces white to gray colored mycelium. Pink snow mold is caused by Microdochium nivalis and produces off-white to pink colored mycelium. Both types of snow mold are active at temperatures around freezing and under wet environmental conditions. Snow molds are most common when an early, deep snow cover prevents the ground from freezing.

Damage caused by snow molds is seldom serious. Generally these areas take a little longer to green up in spring. Gently raking the affected areas of lawn using a leaf rake will promote drying and help to suppress further fungal growth.

The severity of snow molds can be minimized by avoiding excessive nitrogen fertilization after the middle of September. Excessive nitrogen after the middle of September can lead to succulent grass tissue that is conducive to the growth of snow molds. Continue mowing lawn until it is no longer actively growing. Tall grass is more likely to mat down and encourage the development of snow molds. Raking leaves in the fall, spreading large snow drifts to encourage faster melting and selectively placing snow fence to minimize snow accumulation in problem spots will also help to minimize the severity of snow molds.

Snow molds are not common every year, therefore a preventative fungicide application in the fall is generally not recommended. Timely cultural practices such as fertilizing, mowing, and raking are usually all that is needed to control snow molds in a home lawn.

If you have lawn or other plant questions please contact me at the University of Minnesota Extension office, Clay County at 218-299-5020, 1-800-299-5020 or email me at nels1657@umn.edu. Check out our website at www.extension.umn.edu/county/clay/