Snow Mold — Preventing, Identifying, and Removing This Fungal Disease

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Snow Mold — Preventing, Identifying, and Removing This Fungal Disease

Snow Mold — Preventing, Identifying, and Removing This Fungal Disease

Snow Mold — Preventing, Identifying, and Removing This Fungal Disease


Snow Mold — Preventing, Identifying, and Removing This Fungal Disease


You've seen it repeatedly: snow suffocates your lawn throughout the winter. But this time, as the snow melts and the temperatures rise, you notice bare patches in your yard. It's snow mold. So, how do you remove it?

Snow mold is a post-winter lawn disease brought on by fungi that prefer cold weather conditions. We'll share how to identify, prevent, and eliminate snow mold to get a lush, healthy lawn once spring arrives.

Understanding Snow Mold

Snow mold is a fungus that kills turfgrass and other lawn grasses in late winter and early spring. But unlike other diseases, snow mold takes to the cold and heavy moisture that typically occurs from snowmelt or long-term moisture.


What is Snow Mold - A lawn fungus thriving in cold, moist conditions


There are two main types of snow mold and some minor ones as well:

Gray Snow Mold (Typhula blight):
Gray snow mold leaves circular patches about one to three feet diameter of dying grass and usually appears as a grayish-white thread. This disease can affect all turf grasses but typically affects cool-season grasses. It doesn't kill the grass roots, so your lawn may be able to recover.

Pink Snow Mold (Microdochium nivale):
This disease is not limited to snow. According to the UMass Extension Turf Program, it can form in wet conditions ranging from near-freezing to 60 degrees. This mold does kill the roots. You'll have to reseed in patchy areas.

The patches can be pinkish-colored and can reach farther down in the turf, where they could damage the root system.

Minor Snow Molds:
Snow scald (Myriosclerotinia borealis) and Corpinus snow mold (also called cottony snow mold) are two minor snow mold types homeowners might run across. Snow scald affects all turfgrass and appears at snowmelt, eventually bleaching the ends of the grass and blackening toward the center. Corpinus snow mold can be circular or irregularly shaped. It rots the grass and has a red tinge on the edges.


Root Cause of Snow Mold - Fungal spores in soil and debris trigger it


Causes of Snow Mold

Fungal spores in plant debris and soil cause snow mold. Snow cover provides a cold, moist environment perfect for fungal diseases. Lawns with stiff soil, thick thatch, and too much nitrogen late in the fall can all increase vulnerability.

Snow mold is more likely when lots of snow falls before the ground freezes.

How to Prevent Snow Mold

By the time the snow falls, it's too late. You've got to stay on top of your lawn care to prevent snow mold. First, you must get that last mow in before the winter storms arrive. This simple act will minimize the moisture near the soil's surface — the drier your lawn is at this point, the better.

Dethatching is important as well.

Make sure you keep your lawn clear of grass clippings, leaves, and other debris. A specialized preventative fungicide to help stop snow mold is also a great help. Avoid fertilizing in the late fall, especially if you have cool-season grasses, which go dormant in the winter to help protect themselves.

If water is pooling in your lawn, that's an issue. Look into having it graded. The more moisture, the more likely lawn diseases like snow mold will take root.

RELATED: 7 Best Dethatchers of 2024

Once the snow does fall, many minds lean toward keeping driveways and sidewalks clear. Be mindful not to pile up too much on your lawn. You don't want to increase the moisture on the lawn, and the time it takes to thaw.


Fungicide Prevention - Apply fungicides to stop snow mold before it starts


Fungicides For Snow Mold Reduction

Snow mold can be prevented by applying fungicides. Fungicides help prevent outbreaks and winterize your lawn. Fungicides keep the fungal spores from escaping as the snow begins to melt.

Preventative fungicides work best when they are applied between your final time to mow and the first snowfall. This must be done at the right time because doing it too early lowers your chance of success. Too late (after the snow has fallen) will do very little to prevent snow mold.

Fungicides are available in both granular and liquid forms. Some of the best fungicides for snow mold include:

  • Scotts DiseaseEx Lawn Fungicide

  • Quali-Pro Propiconazole 14.3

  • Pillar G Intrinsic Granular Fungicide

  • Heritage G Fungicide

  • Headway G Fungicide


Fungicides will work against snow mold, but they should not be misused. Don't use any fungicide without gloves and eyewear. Keep pets and children away from treated surfaces until the fungicide has completely dried or penetrated the soil, per product directions.

You can always call a lawn service company if you're still dealing with snow mold year after year, no matter how hard you try.

RELATED: Pet-safe lawn care products: 3 things you must know


Post-Snow Mold Action - Wait for warmer weather to repair snow mold damage


How To Remove Snow Mold on Your Lawn

Once snow mold has set in, it's a waiting game. What's done is done. Once it starts warming again, you can begin repairing the damage. Start by gently scraping the area where snow mold developed with a rake. Avoid being over-aggressive, as it can tear already damaged grass. Take any clippings, dead grass, or debris dug from snow mold growth and dispose of it away from your lawn to avoid spreading pores. Do not place any debris in a compost pile.

Snow Mold and Allergies: What Homeowners Should Know

Snow mold is a lawn disease but can also be a health issue if you have allergies, asthma, or other respiratory issues. Its spores fill the air when they multiply. Many experience sneezing, nasal congestion, and an itchy throat if snow mold is around.

Avoid raking or mowing until you get it under control.

Too much watering in early spring will accelerate snow mold by adding moisture to the lawn, so don't water until the lawn has dried out naturally following the snowmelt.

If homeowners take the appropriate steps to reduce exposure and prevent snow mold from developing in the first place, they can keep their health and lawns free from the damaging effects of snow mold.


Snow Mold — Preventing, Identifying, and Removing This Fungal Disease - infographic


FAQs on Snow Mold 
 

Is snow mold bad for my lawn?

Snow mold usually only grows on grass blades but leaves roots damaged if not treated.

Do pets and people get sick from snow mold?

The snow mold is usually not toxic, but don't touch it if you have allergies or respiratory problems.

When does snow mold come out?

Snow mold usually thaws out within a few weeks when temperatures start warming, and the dry weather is back.

Quick Summary

Snow mold is a fungal disease appearing after snow melts in the spring. Like other fungi, snow mold variants love moisture. They also thrive in cold temperatures. Out of the two main types, gray snow mold is typically easier to recover from. It doesn't kill the roots like pink snow mold, so your grass has a better chance of recovery.

To help prevent snow mold, homeowners can mow before the snows arrive, dethatch and aerate their lawns, and avoid fertilizing late in the fall. Applying a preventative fungicide helps as well.


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