Mold from snow is actually a fungal lawn disease that occurs if snow or wet leaves linger on your lawn for too long. If untreated, this fungus can permanently damage your lawn. To prevent this damage, mow, rake, and dethatch your lawn before winter. Applying specialized products is a must, too.
If you live in the North, you probably know what snow mold is, even though you might not be sure how to prevent it or treat it. On the other hand, if this is your first time hearing about this problem, you’ll be glad to know that I am about to answer all the important questions regarding this turf disease, including the following:
- What is snow mold?
- What are the first snow mold signs?
- Is snow mold dangerous for humans and pets?
- How to prevent snow mold or get rid of it?
Stay tuned! It will help you keep your lawn healthy year-round.
- 1 Snow Mold Defined
- 2 What Are The Signs Of Snow Mold & When Do They Occur?
- 3 How To Prevent Snow Mold?
- 4 Is Snow Mold A Health Hazard?
- 5 FAQs
- 6 My Final Words
- 7 About The Authors
Snow Mold Defined
As I read in the highly-appreciated This Old House magazine, snow mold is a lawn disease caused by a fungus. It got its name for two reasons. First, it looks like snow. Second, it usually occurs after the snow melts.
But I know what you are asking yourself: what grasses does snow mold affect the most? The article explains that snow mold affects most types of grass, especially cool-season grasses that stay covered with snow for a long time.
The experts from the University of Illinois’ Integrated Pest Management Department explain that most Midwest turfgrasses are susceptible to snow mold too. They list the following types of grass:
- Kentucky bluegrasses
They also list two types of snow mold:
Gray Snow Mold (Typhula Blight)
Gray or speckled snow mold is also called snow scald. I had this type of snow mold in my yard, and it made grass blades turn grayish-white. Since I did not treat it right away, it soon created circular bare patches in my lawn, too. The photo above is courtesy of noricum.
Pink Snow Mold (Fusarium Patch)
I have not seen pink snow mold, but as I read in the already mentioned article from This Old House magazine, it leaves whitish-pink patches and can cause your grass to die just like the gray mold. In fact, it is more devastating, as it often kills both grass blades and roots and stays active in higher temps as well (up to 60 degrees Fahrenheit). Hence, your grass cannot regrow after an infestation of pink snow mold. The photo above is courtesy of Simon.
What Are The Signs Of Snow Mold & When Do They Occur?
Professor of Turfgrass Science from Penn State University, Peter Landschoot, explains that Fusarium patch or pink snow mold symptoms and signs can be first spotted when the snow cover starts melting. It usually happens in late winter or early spring. He lists the following symptoms:
- Pink coloration
- Tiny spore-bearing structures called sporodochia (can be seen only with a powerful hand lens!)
- Pink, white, or tan patches of dead and matted grass surrounded by a ring of copper-colored grass.
- White fluffy fungal mycelium
As Professor Lanschoot goes on to explain, signs of gray snow mold damage show when the snow cover melts, too. Here are the most notable symptoms of gray snow mold or Typhula light:
- Small (0.5 to 2.5 mm), reddish-brown, rounded fungal structures (so-called sclerotia) on the grass leaves and crowns
- White or tan crusted patches of dead and matted grass that resemble papier mâché (they often cover large areas, like in my case)
- Dense gray fungal mycelium
How To Prevent Snow Mold?
As I have learned from my experience, snow mold can be quite a nuisance. Luckily, it is possible to prevent it and even get rid of it. Bailey Benningfield and Samantha Allen from Forbes magazine suggest the following methods to battle both gray snow mold and pink snow mold: The photo above is courtesy of cinonetwork.
- Mow your lawn short before the winter starts to prevent moisture from being trapped in the soil.
- Apply specialized preventive fungicides.
- Dethatch your lawn year-round to reduce the amount of moisture in the soil and prevent fungus growth. It would be best to maintain a thatch layer of ¾ inches.
- Secure proper drainage to avoid your lawn getting soaked as snow melts. If you notice pools of water, cover them with a layer of topsoil.
- Fertilize your lawn in early spring or summer. Do not fertilize cool-season grasses in late fall since they have probably begun going dormant.
- Rake leaves and remove grass clippings to prevent moisture build-up.
I would just add an obvious thing – do not make a snow pile on your lawn!
Is Snow Mold A Health Hazard?
Cory Ferrer from the reputable LawnStarter company warns that molds have a long history of creating problems for humans. Lawn molds, such as pink or gray snow mold, are no exception to this rule.
As Cory explains, snow molds trigger allergies and cause issues for people with pre-existing lung diseases. Hay fever and other mold allergies impact up to 20 percent of the population, including me, unfortunately. If you are not sure whether you suffer from these allergies, check for the following symptoms:
- Runny nose
- Sore throat
- Itchy or watery eyes
I just want to warn everyone suffering from asthma to be extra careful! I found a great video on this subject:
Is snow mold harmful to humans?
Snow mold is harmful to humans, especially people who suffer from allergies or have a pre-existing lung disease. If you have asthma, you should be extra careful not to come in contact with pink or gray snow mold, warns Cory Ferrer from the LawnStarter company.
How do I get rid of snow mold?
To get rid of snow mold, regularly mow and fertilize your grass. Rick Pietrick from Best Greening Lawn Care service explains this makes the snow molds disappear. To expedite the recovery, gently rake the affected areas to remove the excess “brown” grass. Apply fungicide only in extreme circumstances.
What is snow mold caused by?
Snow mold is caused by cold-weather fungi that primarily affect cool-season grasses, as I read in the Scotts magazine article. You usually cannot notice the symptoms until the weather warms and snow melts.
What are the symptoms of snow mold?
The symptoms of snow mold depend on which of the two types of snow mold you’re dealing with. M. Bess Dicklow from the University of Massachusetts Amherst explains pink snow mold makes the grass look bleached white with a pink margin, while Typhula blight produces circular patches of gray-brown turf.
My Final Words
As you can see from the info I have provided, it is much easier to prevent than to remove snow mold. That is why you should try to apply all the listed preventive measures. It will help you avoid the snow mold problem, which can harm both your lawn and your health.
If you have any questions, leave a comment. Please share this article, too!