Two types of snow molds can rear their ugly heads in spring: pink and gray.

Here in the Northeast, we need to watch out for gray snow mold, also known as typhula blight, which can be caused by one of two fungi; Typhula incarnata or Typhula ishikariensis. Of the two, the latter is the bigger trouble maker, and if your lawn becomes seriously infected, it could kill the grass.

However, most of time if either occurs, the lawn is able to rebound with a little extra care.

Gray snow mold thrives in the thatch of lawns when we have had snow before the ground is able to freeze. Snow is a great insulator; if the ground freezes first, the snow will keep the ground frozen all winter. This is the way winter is supposed to be. However there are those years when the air temperatures remain warm, never allowing the ground to freeze before it snows, which may lead to gray snow mold.

The fungus looks like roundish patches of light brown, matted grass that often have a grayish “crust” to them, hence the name. These patches can vary in size and if severe can merge together forming strips. It can occur in sunny or shady locations and will cease growing once the temperature gets above 45 degrees or the surface dries.

Although we are helpless when it comes to managing air temperature and snow there are a few tips we can practice to help reduce the probability of gray snow mold developing.

For starters, keep your lawn raked; a layer of leaves or pine needles has essentially the same effect as snow when it comes to insulating. Leaving them on your lawn keeps the cold air from reaching the soil and freezing it. Even if the air temperatures have been low enough to freeze the ground around the leaf-laden lawn, the leaves will protect the fungus and give it a cozy home until spring.

Keep in mind also that excessively long grass can have the same insulating effect when it becomes matted down. So continue to mow until your lawn has stopped growing. And don’t leave clumps of grass on the lawn.

You should also put down a winterizer fertilizer. If you look at their nutrient makeup, you’ll notice they are low in nitrogen. Fungi are fond of nitrogen, so this is the time of year you don’t want to be using too much of it.

You also don’t want to have too much thatch build up. This layer of dead clippings and plant debris that develops between the crown of the plant and the soil is where the gray mold grows over winter. Keeping the thatch of our lawn about 1/2-inch-thick is recommended.

Finally, continued compaction of snow on unfrozen ground has been linked to snow mold development. Whenever possible, do your best to reroute foot traffic every so often so a compressed path isn’t created.

Even if you take all these precautions, you may find mold has developed when the snow melts in spring. Just remember it’s not a devastating disease, just ugly. It seldom requires a fungicide treatment because it quits growing once the temperatures warm and the lawn dries.

If you end up with snow mold come spring, get out there with a leaf rake and rake over the area, gently lifting the matted brown grass up so air can circulate down to the crown and soil.

Come summer, check your thatch and thin it out if it’s too thick.

Bottom line: this disease can be easily prevented through lawn maintenance and some old-fashioned, great winter weather.

Nancy O’Donnell owns Perennial Graphics Nursery in Schaghticoke, N.Y.