For some people winter is a thing to bemoan as they wrap up in sweaters and blankets, counting down the days until summer returns. For others, winter is a time to enjoy the snow, skiing, sledding, ice fishing, snowshoeing, and other cold-weather activities beckon.
Of course, winter also has the ability to affect your home and yard in ways that might not be evident until the warmth of spring starts to melt the snow. While the cold might seem to prevent microbes from thriving, there are certain types of snow mold that can endure and even come to thrive once the warmth returns.
This strange type of lawn fungus is opportunistic and makes a home for itself in patches of dead grass and lingering leaves. For many people, the presence of snow mold can cause allergic reactions and potential asthma attacks. One of the most obvious signs of a snow mold problem can manifest as dead areas of previously healthy grass as well as discolorations in the turf. In many of these cases, leaves and other affected materials may also release an unpleasant odor.
Understanding Snow Mold
As strange as it may sound, there are different types of snow mold. The two most common are Microdochium nivale, which is more commonly known as Pink Snow Mold and Typhula incarnata, also known as Gray Snow Mold.
Trace amounts of these fungal microbes live in the soil. They have the potential to slowly take advantage of your turf during the cold, wet periods of the winter. Their presence on the surface then allows them to release spores and foul odors when the snow melts in the spring.
Pink Snow Mold
This type of soil fungus damages the blades of grass as well as the roots. It tends to cause a relatively circular dead spot in the turf. The remaining material tends to have a somewhat pinkish hue with shades of a rust color at the border of the dead spot.
It can develop any time the turf is cold and wet. Ideal conditions tend to be 40-degrees or lower. Pink snow mold is even more likely to be an issue during a long, wet spring, or a wet, cold fall. When it develops in the fall it gains a foothold and continues to spread. Excess thatch and stray leaf debris can increase your chances of a pink snow mold problem.
Once it establishes a presence in the turf, grass will struggle to grow and often fail to even germinate until the temperature starts to hold above 55-degrees.
Gray Snow Mold
Gray snow mold tends to make the affected area look white, pale, or even like it has been bleached. It tends to develop under snow piles and established snow drifts. The affected patches often have an irregular shape. The wet saturated soil under the snow pile or drift stays wetter for longer, which helps the gray snow mold thrive.
Most gray snow mold problems kill the blades of grass. However, a severe case can cause damage to the roots and result in dead patches. The fungal presence tends to remain in the soil for many months after the thaw.
Grass seed might germinate and grow sparsely during this time, and the damage to the turf is usually noticeable. The larger and wetter the affected area is, the longer it will take for the fungal presence to abate.
Understanding Snow Mold Triggers And Conditions
Since trace amounts of snow mold spores live in virtually all soil types, they are hard to eliminate. There are several factors that can increase your chances of developing a snow mold problem in the spring. Some of them include the weather from the previous fall.
An early fall snow that melts and soaks the soil can provide snow mold spores with the moisture they need to propagate quickly. When the lawn is covered by snow, they can continue to affect the saturated soil.
Lingering leaf litter, thatch, and other organic debris can also provide snow mold spores with an ideal environment to develop. The organic matter holds moisture while also providing trace nutrients that fungal spores can use in the reproductive process. They also tend to hold water during the spring thaw. Thoroughly raking and thatch management in fall can reduce your chances of developing a snow mold problem on your lawn the next spring.
Low lying areas and depressions in your turf can also provide an attractive environment for snow mold spores. These areas tend to hold moisture in the fall, helping spores to bloom. Then again in the spring, they tend to stay wet for longer.
During the winter you may want to keep an eye on snow piles and lingering drifts in your yard. These areas tend to stay saturated in the spring and increase your chances of developing a localized snow mold problem. These conditions are more suited to gray snow mold.
Snow drifts or large piles created by shoveling your driveway and sidewalks increase the risk of snow mold. In spring, these drifts and piles melt more slowly, saturating the soil beneath—the perfect environment for snow mold.
Snow Mold Remediation And Lawn Restoration
Snow mold prefers cold, wet conditions. They tend to go dormant once the average temperature stays at 55-degrees or warmer. Once the soil warms you should thoroughly rake away any leaf debris, lingering thatch, and other organic material and attempt to reseed the compromised section of lawn. Fungicide won’t help kill the spores lingering in the soil during the summer, as the damage has already been done.
Preventing Snow Mold Problems
The best method for handling a snow mold problem is to take a preventive approach. Having a trained professional apply a commercial grade fungicide in the fall will help arrest the activity of any developing mold spores before they have a chance to establish a significant presence. This includes noting where snow piles and snow drifts tend to build up on your lawn.
Mowing your grass to a height of around 1½ inches when the leaves start to fall and then making a concerted effort to dethatch the turf will limit the presence of organic material. Raking away all leaves from your yard will further help to reduce the soil’s ability to retain cold moisture and areas that can harbor snow mold spores.