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Nasty-looking Snow Mold is appearing

Unsightly Snow Mold is rearing its ugly appearance on our lawns after a cold and snowy winter.
Unsightly Snow Mold is rearing its ugly appearance on our lawns after a cold and snowy winter.
Duane Sedlock

This past winter we have experienced a long period of snow cover so conditions are perfect for the appearance of Snow Mold.

First, there are two types of Snow Mold; Gray Snow Mold or Typhula Blight, and Pink Snow Mold also known as Microdochium Patch or Fusarium Patch. Snow Mold is a fungal lawn disease which infests almost all types of grasses that endure a period of freezing temperatures and snow cover. It may cause your lawn to have an unsightly appearance, especially after the snow melts. But Snow Mold can also develop without snow cover. If it is cool, rainy, and overcast, then the disease can become active and affect the lawn. It is not uncommon to find both Gray and Pink Snow Mold together.

Gray Snow Mold grows by expansion of mycelium (the white fibers of fungus) under the snow. It can't develop if there is not a period of snow cover on your lawn. If you do have an outbreak of Gray Snow Mold, it is a good idea to reduce any piles of snow that may remain, especially in shady areas. The longer the snow remains the more moisture and cool temperatures are present.

If you see patches of Gray Snow Mold as the snow melts, wait until the grass is dry and then rake the patches lightly with a leaf rake. That should break up the mold patches and increases air circulation in the grass. This will usually kill the mold (Any mold that you do rake up should be tossed away in the garbage and never used in mulch piles.) and the patches should normally fill in as spring proceeds. If not, you may need to overseed in the area of the damage. Fungicides are rarely used on lawns for Gray Snow Mold.

The second type, called Pink Snow Mold due to its pinkish color, is very similar to Gray Snow Mold, but develops without snow cover. While the grass is wet, the mycelium starts out white and resembles cobwebs, as it matures it turns its pink or salmon color. The mycelium quickly disappears as the grass dries. Usually by keeping your lawn cut relatively short and cleaning up leaf litter and debris in the fall, you should be able to avoid this type of mold. Pink Snow Mold infects the crown of the plant and can cause more severe injury than Gray Snow Mold which only infects the leaf tissue.