Springtime is celebrated around the world as a time of renewal and rebirth. That is, unless your lawn is covered with gross fuzzy mold.
If you found your way here, your yard might have snow mold. But what is this stuff? Is it dangerous? How can you get rid of snow mold?
In this article we’ll cover everything you need to know about snow molds, what to do when your lawn is afflicted, and how to prevent snow mold. Along the way, we’ll discuss the health risks of dangerous molds that might attack your lawn or home.
- What is Snow Mold?
- How Does Snow Mold Form?
- Types of Snow Mold
- How Dangerous is Snow Mold?
- How To Get Rid of Snow Mold
- 8 Ways To Prevent Snow Mold
- Make Your Lawn Snow Mold Resistant
- When To Call a Lawn Care Pro
What is Snow Mold?
Snow mold is the common name for several species of cold-resistant fungi. They grow on lawns beneath snow during winter. This fungus damages grass by creating circular growths, often with dead patches at the center.
Snow molds usually last a week to a month after the snow melts, and cause lasting damage to your lawn. This fungus also causes allergies and creates health problems for people with chronic respiratory diseases like asthma. We’ll cover these problems in greater detail further down the page.
How Does Snow Mold Form?
All winter long, your grass lies dormant. A cozy blanket of snow creates pockets of cool, moist turf. Throw in some soggy debris like dead leaves or lawn clippings, and you just made the perfect breeding ground for snow mold.
While snowdrifts hide this habitat from view, the fungus has all winter long to conquer your yard. In the springtime, the melting snow reveals fuzzy white patches all over your lawn. Snow mold will grow wherever it finds the environment, so keep your lawn neat in the fall.
Types of Snow Mold
Snow mold comes in two types, gray and pink. Here we’ll run down the differences and important characteristics of each.
Gray Snow Mold
Gray snow mold, also called speckled snow mold and typhula blight, has a fluffy appearance, like wisps of cotton growing in your grass. It often sprouts well-defined circular patches. While known primarily as a turf disease, typhula blight also attacks wheat and destroys crops.
Gray snow mold grows best in the Great Lakes region and other temperate parts of North America with regular snowfall.
Gray snow mold is less damaging than pink snow mold (the other kind of snow mold). Gray snow mold afflicts grass stems but leaves the roots alone. Once treated, your grass will grow back easily.
However, typhula blight creates underground structures called sclerotia which survive during the summer months. You have to treat your gray snow mold thoroughly to keep this fungus from bouncing back next year.
Pink Snow Mold
Pink snow mold, also known as Fusarium patch, is bad news for your yard. This fungus attacks roots as well as grass blades, leaving rings of dead, barren earth on your lawn. Feared by golf course owners, this blight also looks fuzzy but with a slightly pinkish hue.
Fusarium patch tends to grow in well-defined circles too. Unlike gray snow mold, pink snow mold doesn’t actually need heavy snowfall. Pink snow mold is most common in colder temperate regions and thrives in spells of cool, damp weather.
How Dangerous is Snow Mold?
Plant molds have a long history of creating problems for humans. Fungus was responsible for the Irish potato famine, and has destroyed billions of dollars worth of wheat and barley in the U.S. over the years. Wheat flour infected with a toxic species of Fusarium also caused massive casualties in the Soviet Union during the Stalin era.
But what about lawn molds?
Snow molds are trouble for anyone with allergies or pre-existing lung diseases. “Hay fever” and other mold allergies are estimated to impact 10 to 20 percent of the population. Symptoms of allergic reactions to snow molds include:
- Runny Nose
- Sore Throat
- Itchy, Watery Eyes
Like all molds that reproduce with spores, snow mold can be hard on your lungs, especially if you have a respiratory condition like asthma.
Fortunately, our research hasn’t turned up specific examples of snow molds causing opportunistic infections in immuno-compromised people. However, many species of plant molds are able to jump from plants to human bodies, so it’s probably not worth taking the risk.
If you have concerns about your white blood cells’ ability to fight off invaders, stay away from all molds, regardless of species.
How To Get Rid of Snow Mold
Your best strategies for keeping a yard free of fungus are preventative. However, hindsight is 20-20. What should you do if the gray or pink snow mold is already here?
Fortunately, snow mold dies off naturally as the air becomes warmer and drier. Depending on weather, snow molds will live from a week to a month after the snow melts.
Carefully rake out clots of matted grass. This will dry the mold more quickly. Once it dies, you may need to reseed or sod your lawn. Plant fresh seeds and spread fertilizer to give your growth a boost.
It might take a while for your lawn to look healthy and green again. You’ll just have to be patient and keep the mold from coming back next season.
8 Ways To Prevent Snow Mold
The best defense against snow mold is prevention. Here we’ll run down the most important things you can do to protect your lawn and your lungs from unsightly patches of fungus.
1. Plant Resistant Grass Types
While no grass is immune to mold, some types are hardier than others. Fine-leaved fescues and tall fescues are the grass types least susceptible to fungus. You’ll find moderate resistance in Delray perennial ryegrass and other fescues like chewings and red.
We place bentgrasses and bluegrasses on the more vulnerable end of the spectrum. Planting these types only increases your risk. Unfortunately, Kentucky bluegrass – one of the most popular cool season grasses because of its cold hardiness and foot traffic durability – has poor resistance to snow mold. Though some strands fare better than others.
2. Don’t Let Organic Debris Build Up in Your Lawn
Soggy layers of dead leaves or grass clippings create the perfect habitat for snow mold. All they need is a thick blanket of snow and their little mycelia are off to the races. Always rake leaves and remove grass clippings before the first snow.
We also recommend you dethatch your lawn at least twice a year. When your yard becomes a thick weave of stolons and roots, you leave plenty of organic debris for a fresh colony of snow mold.
3. Keep Your Grass Mowed
If your grass gets long enough to lay flat under the snow, you’ll create a thick mat of crannies and nooks: the perfect place for snow mold to get a fresh start in life.
When you notice your grass turning yellow and becoming dormant in the fall, we recommend mowing to about 1.5 inches. This will keep your turf from getting matted and tangled under the snow.
4. Let Your Lawn To Go Dormant
Grass lives best when it spends the winter dormant. It’s also more vulnerable to snow mold if it hasn’t gone to sleep when that first blizzard hits.
This is why you should never fertilize your lawn when you’re expecting snow in six weeks. Stimulating grass growth can postpone your lawn’s winter dormancy, giving mold a better foothold on your turf.
5. Don’t Let Your Lawn Become Soggy
Wet lawns create the perfect environment for fungus. Most yards need between 1 to 2 inches of water a week, either from rainfall or irrigation. Stretch too far past that, and you might overwater your lawn.
You’ll also need effective drainage across your landscape. If you notice standing water sitting around your yard, you may need sandier soil, grading and sloping, or runoff solutions like dry creek beds. Excess water creates a damp environment perfect for snow mold.
6. Apply Protective Fungicide
There are broadly two types of fungicide, protective and eradicant. Protective fungicides are designed to spray on your lawn or garden before fungus takes hold to prevent infection.
Eradicant fungicides are typically much stronger and designed to destroy mold once it’s arrived. A good spritz of protective fungicide will lower your yard’s chance of infection.
7. Don’t Over-Fertilize
Fertilizer provides wonderful food for your plants, but it also feeds other organisms. Snow mold, for example. While types of fertilizer vary, a good rule of thumb is 1 pound of nitrogen or mixed fertilizer per 1,000 square feet. Beyond that, you might create a feast for your fungus.
8. Keep Snow from Piling up During Winter
Like its namesake suggests, snow mold likes to grow under the snow. If you leave large snow drifts on your yard from shoveling or plowing, you might just invite the mold to a cozy little cave.
Make Your Lawn Snow Mold Resistant
No one wants mold growing on their lawn. Springtime fungus can make you sneeze while blemishing your yard’s curb appeal.
The best defense against lawn fungus is prevention. To avoid creating a habitat for snow mold:
- Clear away organic debris
- Mow your grass before winter
- Maintain effective drainage
- Apply fertilizer at the right season
- Clear away snow piles
- Plant fungus-resistant grass types
If snow mold does spring up in the springtime, keep the area dry and then repair your yard. Also, stay away from snow molds in your yard – and any mold growing inside your home – if you have allergies, a chronic lung disease, or a compromised immune system.
When To Call a Lawn Care Pro
Not sure whether you’re dealing with snow mold or something else? Want a pro to care for your lawn year-round? A nearby LawnStarter lawn care pro will keep your lawn green and healthy to ward off snow mold and other lawn diseases and pests.
Main Photo Credit: Maasaak, CC BY-SA 4.0, via Wikimedia Commons