Snow Mold?

As winter melts away into spring, things may start to reappear in your yard that was previously hidden by winter’s thick blanket of snow. You may rediscover that tool that was not put away before the first significant flurries, or just the welcome signs of spring as your perennial bulbs begin to push through the surface. An unwelcome sight, however, may be the appearance of a fungal lawn disease called snow mold.

What is Snow Mold?

Snow mold grows from the spores of two types of fungi… a gray mold called Typhula blight, and a pink variety called Microdochium nivalis, (also known as Fusarium patch). These molds are responsible for causing the lawn disease which resembles a spiderweb-like white substance. Snow mold begins growing when temperatures start to warm enough for the fungi to thrive. The pink snow mold can flourish from 32 degrees up to 60 degrees, as long as your lawn is damp, while the gray mold can grow from about 32 degrees to 45 degrees Fahrenheit.

Is Mold Dangerous to Your Lawn?

Though snow mold can cause your lawn to look unattractive, the fungal growth is typically not a serious concern and will dry up as the weather warms and the sun dries out and kills the infected lawn. To accelerate this process and get rid of the snow mold earlier, there are several things you can do:

  • You can spread out the snow mold with a rake (being careful to not damage the grass trying to grow). This will help get airflow to the infected area and dry it out faster.
  • Once your lawn is dry enough you can mow it shorter than usual. Tall grass can retain more moisture, which contributes to the fungal growth. Continue mowing the lawn in this manner until you notice the mold is no longer growing.

 Mold Prevention

There are a few things you can do to try to prevent the unsightly growth of snow mold:

  • In late fall be sure to mow your grass to a short height and then rake up and bag the grass clippings and any leaves that are collecting in your lawn. This organic matter can trap moisture and create a perfect environment for the snow mold fungal growth to take off as the snow melts and temperatures get to the right levels.
  • Do not use a nitrogen fertilizer in the fall if you have had issues with snow mold.
  • If you have larger piles of snow in certain areas, it is a good idea to spread out the snow so that it melts more quickly and doesn’t retain the moisture as long in those spots.

Snow mold is not usually a serious concern, but it can sometimes persist into late summer and fall if the weather remains damp and cool enough. If this happens it can do more damage to your lawn. Years with earlier, deeper snows often result in more snow mold growth than the winters that are colder and bring less snow. This is because the early snow blankets the ground and protects the fungus from harsher temperatures.

Snow Mold Prevention

If you’ve been through an occurrence of snow mold, chances are you’ll want to prevent it from ever striking again. Here are some of the steps you can take to protect your beautiful lawn from snow mold damage:

  • Consider resistant species of grasses. Although all types of turfgrasses are susceptible to both pink and gray snow molds, Kentucky bluegrass and fescues are the most resistant.
  • Follow a balanced fertilization program. Particularly, excessive over-application of nitrogen fertilizer in the fall can create a favorable environment for molds to thrive. Our lawn care treatment programs are specifically formulated for Indiana lawns and can help prevent snow mold from occurring.
  • Follow through on lawn care responsibilities. Don’t skip that final treatment of the year! During the late fall, keep mowing the lawn until it enters a state of dormancy. Also be sure to remove leaves, clumps of mown grass, or any other materials like hay or mulch from the yard before snowfall. These materials retain moisture on the turf and provide insulation, which is exactly what snow mold needs to thrive while it feeds on your lawn.
  • Prevent snow drifts or large piles of snow on the lawn. Areas where large amounts of snow are allowed to accumulate on the grass will become much more vulnerable to snow mold. These slow-thawing piles set the stage with the right moisture and insulation for a mold horror story.
  • Be consistent with lawn care. In addition to a balanced fertilization program like ours, be as consistent as possible with maintaining a healthy mowing height and irrigation program. Never remove more than ⅓ of the total length of the grass—even if you’ve missed a mowing and need to “catch up.” This stresses the lawn—as does long periods without water. The healthier the lawn is on a consistent basis, the more resistant it will be to diseases.
  • Give shady areas a little TLC. mold is more common in densely shaded areas, mainly because shady areas take longer to dry out after the thaw. Consider taking steps to improve drainage efficiency in shady lawn areas, and certainly remove fallen leaves or other debris from these areas. Perhaps the kiddos should build Frosty in a more sunny spot of the lawn, as well.

How to Treat Snow Mold & Minimize Damage

When snow mold attacks, homeowners need to know the steps to take to minimize the damage and treat the affected areas. The Purdue University Cooperative Extension Service recommends against the use of fungicides on residential lawns, which are toxic and can also damage or kill turfgrass. However, immediate steps can be taken to stop the growth of snow mold and hasten the lawn’s healing process in lieu of fungicides.

In a nutshell, here’s our advice for how to stop mold: groom and resume. Groom your lawn by raking through the affected patches to loosen grass that has become matted. A mowing may also help to get more air circulating through the matted grass plants. After grooming, resume fertilization treatments to help restore the health of your turf.

Share this Post