All About Gray Snow Mold: What It Is and How to Handle It

Gray snow mold sounds like something out of a winter nightmare for turfgrass. Typhula incarnata is a type of fungus that causes this problem. It wreaks havoc on lawns, golf courses, and athletic fields, especially when there’s a good layer of snow hanging around for a while. If you’ve got cool-season turfgrass, you’re at risk. But don’t worry... there are ways to deal with it that won’t have you tearing your hair out.

What Are the Signs of Gray Snow Mold?

Gray snow mold doesn’t show up until the snow starts melting away, which is usually in late winter or early spring. What you’ll notice first are patches of dead, matted grass blades. These patches look almost like someone dropped a layer of papier-mâché over your lawn. The size of these patches can measure up to several feet across, and if things get bad, they can even join up to create big areas of blighted turf.

You might also spot gray fungal growth near the edges of where the snow is melting. This fungal fuzz is a dead giveaway for gray snow mold. And if you’re really getting in there to check, look for tiny reddish-brown fungal structures (sclerotia) embedded in the leaves and crowns of the grass—these are another telltale sign of gray snow mold.

How Does Gray Snow Mold Develop?

The disease starts when sclerotia (those reddish-brown fungal structures) begin to germinate under the snow. Once they get going, the fungus spreads from one plant to another. This happens all while your lawn is sitting under a cozy blanket of snow. The worst part? The fungus thrives in the cold, wet conditions right at the snow-turf interface, usually when the soil isn’t frozen.

Once the snow melts and the turfgrass is exposed to the sun again, the fungus dries up and stops spreading, but the damage has already been done. The good news is that while gray snow mold can mess up the leaves, it usually doesn’t kill the roots or crowns of the grass. This means that, come spring, your lawn can bounce back, assuming you take some proactive steps.

Where Does Gray Snow Mold Hit the Hardest?

You’re most likely to see gray snow mold in areas where snow piles up... think along sidewalks, driveways, or spots where snowdrifts form. The longer the snow sits there, the worse the mold can get. It’s not picky about where it shows up, either, but it does tend to be worse on close-cut turf, like putting greens or heavily fertilized lawns. New lawns that haven’t had time to mature are also prime targets.

How to Prevent and Control Gray Snow Mold

Here’s the good news. For most home lawns, gray snow mold doesn’t mean you need to break out the heavy artillery like fungicides. There are a few simple cultural practices that can help keep it at bay.

✅ Keep mowing into the fall: Don’t stop mowing just because it’s getting colder. Mowing well into the fall helps keep the grass from getting too thick, which is exactly what the fungus loves.
✅ Avoid piling snow on your lawn: When shoveling or using the snowblower, try not to create big snowbanks on your grass. The more snow you pile up, the more likely you are to have issues.
✅ Use moderate nitrogen fertilizer in the fall: Over-fertilizing with nitrogen can lead to lush, vulnerable turf that snow mold thrives on. Keep it moderate to give your lawn the best shot at staying healthy.

In the spring, once the snow melts, you can give your lawn a hand by lightly raking any crusted areas to break up the matted grass. Then, apply a little nitrogen fertilizer to kick-start growth and help the lawn recover.

Chemical Control: When and Why to Use It

Fungicides can be helpful if you’re dealing with high-value turf, like golf course putting greens, or if you’ve just seeded a new lawn. If you’re going this route, preventative fungicide applications are key. You’ll want to apply them before the first big snow hits in the fall, usually in late November. But keep in mind that fungicides applied after symptoms appear in the spring won’t do much good.

For the best results, using a combination of fungicides with different active ingredients tends to be more effective than sticking with just one.

Snow Mold: Prevent It or Fix It Later?

Most golf courses hit their tees and greens with preventative fungicide treatments in early and mid-winter. Why? Because no one has time for turf recovery during the busy spring season. For other turf managers, it’s often about curative applications in the spring, but only when snow mold outbreaks get severe.

If prevention’s your game, the best bet is a fungicide that combines systemic and contact action. Some go-to options: Headway, Instrata, Concert, and Enclave. If you stay ahead of the game, you can keep your turf ready for whatever spring throws at it!

In the end...

...gray snow mold can be a pain, but it’s usually not the end of the world for your lawn. By following a few simple steps, such as mowing late, avoiding snow piles, and using the right amount of fertilizer, you can usually keep it under control. And if you’re dealing with a more high-value turf area or a brand-new lawn, a little chemical help in the fall can make sure your turf comes through the winter looking great.