Snow Mold on Colorado Lawns: How to Spot and Treat It

snow mold in lawn

As winter retreats, leaving behind its blanket of snow, a new challenge emerges: snow mold in your Colorado lawn. But fear not! In this guide, we’ll delve into how to identify, treat, and prevent snow mold in Colorado, from raking the lawn to applying fertilizers.

What causes snow mold?

Snow mold is a fungal disease that plagues many lawns across Colorado during the winter months. Sadly, certain grasses common in Colorado, like Kentucky bluegrass, are susceptible to snow mold.

It is characterized by gray or pink patches on the grass, and it thrives in cold, wet conditions, particularly when there is prolonged snow cover. These fungi love the dark, damp environment under the snow, where they can grow and spread. 

Gray snow mold, also known as Typhula blight, and pink snow mold, known as Microdochium patch, are the two main types that homeowners may encounter in the Centennial State.

What snow mold looks like

snow mold (Typhula incarnata)
William M. Brown Jr. | Bugwood.org

Snow mold manifests as bleached circular patches on lawns, typically appearing after the snow melts away in the spring. Here are the key snow mold symptoms to help identify the two most common types of snow mold:

Gray snow mold

  • Circular patches of light yellow, straw, or brown-colored turf, typically ranging from 6 to 12 inches in diameter.
  • Grass blades within the affected areas may appear matted down and covered with gray or white webbing, known as mycelium.
  • Reddish-brown, rounded fungal structures called sclerotia may be present in the grass blades.

Pink snow mold

Pink snow mold
Pink snow mold
Bevegelsesmengde | Wikimedia Commons | CC BY-SA 3.0
  • Circular patches initially display an orange-brown hue, which transitions to dark reddish-brown, and finally light gray or tan as the disease progresses.
  • A faint growth of light pink mycelium may be visible at the edges of the patch, particularly noticeable in the early hours of the day.
  • Under prolonged periods of wetness, pink spores may become visible within the affected areas.

How to treat snow mold in Colorado

gray snow mold fungus on grass
Kris Lord | Flickr | CC BY 2.0

Once the temperatures consistently exceed 45 degrees Fahrenheit or the turf begins to dry out, snow mold activity typically ceases. However, the affected turf may take longer to fully recover afterward. Here are some things you can do to treat snow mold in Colorado:

  • Rake the patches: Lightly raking your grass will help break up the crust and allow the turf to dry out, which will help treat snow mold.
  • Apply fertilizer lightly: Consider applying fertilizer, particularly in early spring, especially if you did not fertilize in the fall. This can help promote new growth and combat snow mold. Check out our guide to know when to fertilize your Colorado lawn.

Colorado State University does not recommend fungicide applications for treating snow mold in spring. Fungicides are only effective as a preventative measure and should be applied in the fall before snowfall to protect against snow mold.

Here’s a video by This Old House showing how to treat snow mold:

Snow mold prevention tips for Colorado

To mitigate the risk of snow mold development during the winter months, implementing a few cultural practices can go a long way. Here are some preventive measures to consider:

Person using sprayer with a fertilizer on a lawn
Shutterstock
  • Apply fungicides in fall: Prior to the onset of winter and snow cover, apply fungicides to protect your lawn against snow mold.
  • Keep your lawn free of debris and snow: Remove dead leaves and avoid allowing piles of snow to accumulate on your lawn, as these can create conditions that are perfect for snow mold to grow.
illustration explaining thatch on grass
Infographic by Juan Rodriguez
  • Dethatch regularly: Follow your Colorado lawn care schedule and dethatch your lawn as needed to improve air circulation and prevent the buildup of thatch, which can be conducive to snow mold.
  • Grade your lawn: Ensure your lawn is graded and has proper drainage to prevent the formation of low areas that can collect water after heavy rainfall or snowmelt.
illustration showing the pH levels of soil
Infographic by Juan Rodriguez
  • Maintain soil pH and fertility: If you commonly experience issues with pink snow mold, consider maintaining a low soil pH and balanced soil fertility through the use of soil amendments.
  • Choose resistant grass varieties: When selecting the best grass for your Colorado lawn, opt for varieties known to be resistant to snow mold, such as fine fescues or warm-season grasses.
mower mowing a lawn
Pixabay
  • Keep your lawn mowed: Continue mowing your lawn until it stops growing in the fall to prevent tall grass from becoming matted under snow cover, which can contribute to the development of snow mold.

FAQ about snow mold

Does snow mold kill grass?

Gray snow mold typically doesn’t kill established lawns, although young seedlings from a late fall overseeding may be susceptible to damage. However, a severe infection by Microdochium nivale, the fungus responsible for pink snow mold, can indeed kill turfgrass.

Which areas are more prone to snow mold?

In Colorado, areas that receive successive rounds of snowfall without sufficient time for the ground to dry out between each round are particularly prone to snow mold. This often occurs in higher elevations, such as the Front Range, where colder temperatures prevail.

Additionally, north-facing lawns, shaded areas, and areas with drifting snow are susceptible to snow mold.

Is snow mold dangerous?

Snow mold can pose risks to individuals with allergies, asthma, or other pre-existing respiratory conditions. Molds produce spores that can trigger respiratory symptoms such as runny noses, sneezing, and watery eyes. In some cases, snow mold can exacerbate asthma symptoms.

However, there isn’t enough evidence to conclusively determine any long-lasting effects on human health from exposure to snow mold. Nevertheless, it’s best to avoid direct contact with it if you can.

Call the professionals

If the thought of battling snow mold leaves you feeling more frosty than festive, why not leave it to the pros? Reach out to a lawn care professional near you for assistance with dealing with snow mold and other lawn care chores. Their expertise can save you time and ensure your lawn receives the proper care it needs to thrive.

Main Image Credit: noricum | Flickr | CC BY-SA 2.0

Maria Isabela Reis

Maria Isabela Reis is a writer, psychologist, and plant enthusiast. She is currently doing a PhD in Social Psychology; and can't help but play with every dog she sees walking down the street.