Snow Mold

Snow mold is a fungus. It symptoms consist of roughly circular patches of dead matted grass (at least 3 to 12 inches). It develops in wet, cool weather when the snow cover lasts for several months as ours has this year. Snow mold begins to grow when the grass is covered with snow before the ground has frozen. Snow mold grows under the snow, but may continue after the snow melts. The fungus lives for years in the thatch and soil, but is mostly never detected due to the weather in our area not being conducive to its growth. There are two types of snow mold: pink and gray. Both types start their growth when the temperature is above freezing. Gray stops growing when the temperature reaches about 45 degrees. Pink stops growing when the temperature reaches about 60 degrees. Treatment of a mild case of snow mold is relatively easy and may actually recover on its own. To encourage recovery, rake the infected area to encourage air circulation. For severe cases, a fungicide may be needed. Spring application of a fungicide is mostly ineffective; it should be applied in the fall and before the snow cover is expected. There are different fungicides for pink and gray mold and the label should specify for which it is intended to treat. If there is extensive damage from the mold, it may be necessary to reseed or sod the infected area. Some of the steps that can be taken to reduce the chances of infection in the future include: » Do not apply quick release nitrogen or high phosphorous fertilizer in the fall when grass is going dormant. Wait to apply after grass is dormant. » Rake and remove leaves before snow cover. » Mow until grass stops growing in the fall. Tall grass is more susceptible to the mold. Mow grass shorter on the final mowing in the fall. » Reduce thatch.