People use the term “snow mold” when they talk about fungal diseases that hurt turfgrass. Two types of snow mold are called pink and gray. They have a few differences, but when the snow on their lawn melts, they both shock people. Because they don’t have healthy turf, they find ugly and dangerous patches on the grass.
Types of Snow Mold
You can also call this pink snow mold “Microdochium patch.” This is caused by the fungal species called Microdochium nivale, which grows on trees. Small spots that are about 8 inches wide may be found when the snow melts. They start out orange or reddish-brown in color, then change to a light tan with pink parts. Pink mold lives in plant waste until fall.
Gray snow mold, also called Typhula blight, is caused by Typhula incarnata, which is found in the woods and on trees. It makes big spots that are 1 to 3 feet wide. The blight makes the grass yellow or gray. It usually comes with mycelium, which is a gray-white, fluffy substance that looks like spider webs.
They both look bad, but pink snow mold can hurt and kill the whole grass plant down to its roots. Most of the time, gray mold grows on the blades of grass.
aren’t active when it’s warm and dry outside, but they’re only asleep. On the grass, you can see tiny structures called sclerotia. Gray snow mold makes them, and you can see them on the blades. They grow when the weather is cold and wet.
Causes of Snow Mold
The mold is caused by the fungi, but there are environmental factors that can start the mold. A layer of snow lets two types of snow mold grow. An early snow that falls before the ground freezes is especially bad. The warm soil melts the lower level of snow, while the snow that hasn’t melted holds water near the surface, making it a good place for bugs to grow.
Anything that gets stuck under the snow can make things worse. That includes leaves, garden waste, and even long blades of grass that get stuck together. Another way that snow mold can grow on a lawn is if the lawn is covered in thatch (dead grass and other debris that clogs the soil and keeps it from drying out).
People often feed their lawns in the fall, which is usually a good idea. It can also happen if the fertilizer is applied too close to the first snowfall, which means the lawn is green and growing when it should be going dormant. This can cause snow mold.
Dealing With Snow Mold
Many people reach for a fungicide when they see snow mold. By the time the mold is found in the spring, it is too late because the damage has already been done. The best thing to do is to give the lawn a good old-fashioned rake. You will pick up any dead leaves and help aerate and dry the soil. There are some places that can start to get better on their own. This, along with the change in the weather, can also help.
Even so, there’s a good chance that some areas won’t grow back and the grass will stay dead. You can fix the damage in those places by reseeding them again When the risk of frost has passed, get rid of the dead grass. Follow the package’s instructions on how to prepare the soil, sow the seed, and grow and care for the new grass that you bought.
Preventing Snow Mold
Keep snow mold from taking hold. Fortunately, there are a lot of ways to stop the problem before it even starts.
Remove thatch. Dethatch the lawn as needed but especially in the early fall using a dethatching rake.
Remove leaves. Leaves should not stay on the lawn all winter. Use a mulching mower to chop them up and leave them on the lawn so they can break down and add nutrients to the soil.
Cut grass shorter than usual. Mow your lawn about 1 to 1 1/2 inches shorter than usual during the last mowing of the season. Make sure to do this when the grass is about to go dormant for the season. Short blades of grass are less likely to become compressed and muddled under the snow than long grass, which is more likely to happen.
Apply a fungicide. Apply a dose of lawn fungicide in the fall to stop snow mold from growing. Most people won’t need to do this.
Fertilize at the right time. In the fall, if you fertilize your plants, do so at least six weeks before the first snowfall in your area.