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Snow Mold Prevention and Treatment


Snow mold can cause problems in late winter when there is snow compacting turf. Learn more about how to prevent this from happening and ways to treat the fungus.

February 2, 2024

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How Fertilizer Feeds Turf

The appearance of snow mold can ruin a golf outing before you even get to the first tee. On golf courses and in regions where cool turfgrass is popular, snow mold prevention is a necessary part of lawn care and maintenance. Today, the experts at SiteOne Landscape Supply are looking at how to prevent mold from forming and what to do if there is a snow mold outbreak.

  • What is Snow Mold?
  • How to Prevent Snow Mold
  • How to Control Snow Mold

What is Snow Mold?

Snow mold is a type of fungus, stemming from the Microdochium nivale fungus, which mimics the look of snow and affects grass while the snow melts. It can be gray, white or pink and can grow on any cool-season turfgrass.

These spores live in the turf year-round but are only active when the temperature is around 30-60 degrees Fahrenheit. Snow mold usually becomes visible between 32-45 degrees. It causes grass to die, leaving the turf splotchy with the mold itself and/or dead spots where the mold has killed the grass. 

Some grasses, like bentgrass, are more susceptible to snow mold. Kentucky bluegrass is moderately affected, while fine fescue is more resistant to the fungus. 

There are two kinds of this fungus. Gray snow mold, or Typhula blight, is either white or light gray. This mold is most often found in the areas below where large snow drifts formed over the winter; the grass stays wet longer, which encourages mold growth. Patches can range from a couple of inches to a few feet in diameter. The good news is that in most cases, gray snow mold doesn’t affect the roots, so the surface blades eventually regrow in warmer weather. 

The pink snow mold, or Fusarium patch, ranges from white to pink in color. This fungus can grow anytime grass is wet and below 40 degrees — not just in the spring, but fall, too. Pink snow mold also kills the turfgrass roots so your grass will not grow back. The patches are usually less than a foot across and can appear all across the lawn.
 

Typhula blight:


Fusarium patch:

How Fertilizer Feeds Turf

Snow Mold Prevention Methods

  • Mow the turf regularly, but especially before snow. Cut the turf shorter than normal before expected snowfall so the grass will retain less water — taller grass can mat down and trap moisture. Do not leave trimmings on top of the turf.
  • Dethatch your customer’s turf at least twice a year.
  • Ensure the area has proper drainage installed before the winter season. Ponding can create the perfect spore breeding ground
  • Rake any leaves before they get wet or they will trap moisture. When possible, remove snow from the turf. Additionally, if you shovel or blow snow off pathways and sidewalks, ensure the piles of snow are not too large, as larger piles take much longer to melt.
  • Apply a mold prevention spray fungicide like LESCO Drax or Concert II. This should occur in late fall before turf growth completely stops.
  • Follow a fertilization plan for your area, but do not fertilize with nitrogen in late fall. Cool-season grasses go dormant in winter, making them less susceptible to snow mold as their blades become dehydrated. With fertilization late in the season, this process gets disrupted, and the nutrients can create a welcome environment for mold spores if not absorbed by the turf.
  • Fertilize in the spring to encourage new growth.
  • Prune or remove large trees that shade the turf to improve air and light circulation.

Snow Mold Control Methods 

While the best treatment is prevention, sometimes snow mold is unavoidable. It typically goes away on its own in the spring once the temperatures warm up and the soil dries. Take care of this fungus with the following tips:

  • Rake over the affected areas gently. This will help get airflow through the blades so they dry faster.
  • Reseed the patches where turf has died if regrowth does not occur.
  • Avoid further fungicide and fertilizer application until these patches grow over.

Shop at SiteOne

SiteOne Landscape Supply is your one-stop shop for all your year-round golf course needs. Associates are available to answer any questions and help you find the supplies for the job. Visit your local branch or shop on SiteOne.com. You can also find help in some of our other agronomic educational articles

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