Spring is arriving. The weather is warmer, the birds are back, the trees are beginning to bud, and my lawn is………white?A winter of record snowfall and sustained freezing temperatures has created the perfect setting for spring “snow”, otherwise known as snow mold. Unfortunately, no lawn is immune – even the lushest lawns at the end of last season are falling prey to the disease. Horizon’s owner, Mike Kukol, wasn’t able to spare his own lawn from a rampant case of it this year. So, what is snow mold, and how do we fix it?
Types of Snow Mold
There are two types of snow mold: Typhula incarnata, or gray snow mold, and Microdochium nivale, or pink snow mold. Like your standard household mold and mildew, snow mold is a fungus which thrives on moist conditions. Most of what we have seen so far this year is the gray type, although pink type has also been spotted.
As these molds go, if we had a preference we would take the gray over the pink. Both types appear because of extensive periods of snow cover; however, the gray type stops spreading and the grass starts to regenerate once the snow has melted. The pink type, on the other hand, thrives in damp, cold weather and continues to create spores and spread itself regardless of snow cover.
Gray Snow Mold
Gray snow mold appears as large (12 to 24 inch) circular patches of light yellow or straw-colored turf often with a light covering of grayish white vegetative threads known as mycelium. The leaf tissue becomes infested with sclerotia, which is mycelium which has hardened and turned a reddish-brown. This can really only be seen by close examination. (If you need proof and you feel like getting up close and personal with your fungus, by all means, be our guest and take a look.) The damage to the lawn may appear more severe than that of pink snow mold, but because the infestation stops when the snow melts away, recovery from the damage is much quicker, and the lawn will bounce right back with the onset of warmer temperatures, some light raking to pull out the damaged grass, a little grass seed and a shot of fertilizer.
Pink Snow Mold
Pink snow mold is found in small circular patches 1 to 3 inches. It starts as an orange-brown color that fades to reddish brown and then to light gray or tan. When trapped under snow cover, the affected areas can expand to approximately 12 inches in diameter. Instead of sclerotia, the mycelium infests the leaf tissue by reproducing into an easily visible fluffy white mass that turns pinkish or salmon-colored as the spores multiply. These spores reproduce in response to sunlight. The spores thrive in cool, wet weather in the springtime and can continue to cause damage until the ground dries out and the air becomes warmer, so it is important to control them with an application of fungicide. Your local licensed lawn care professional will know exactly the right kind and the right amount of fungicide to use. And we suggest that you don’t use a rake to remove the infected grass – the active spores will spread from your rake to other areas of the lawn, as they will from your shoes (or your kids’ shoes, or your dog’s paws). Keep away from the infected area as much as possible until the lawn recovers, including using a lawn mower, which can spread the spores from the rotation of the wheels.
Treatment and Care
If you just installed a new seed lawn in the fall, you may see significant snow mold damage. The young turf is not able to withstand disease as a easily as a well-established lawn. Don’t be discouraged – grass finds a way to keep on growing. You might find that some areas will need renovating, but additional seed and fertilizer will do the trick. Snow mold also likes to feast on perennial ryegrass and tall fescue. Kentucky bluegrass seems to withstand the onslaught the best. Whatever type of grass you have, and however badly your lawn is infected, be assured that snow mold is temporary, and with the right treatment and care your outdoor space will be as green as new.
For more information on snow molds and other plant diseases, visit the Rutgers Cooperative Extension Service website, our partner in helping us perfect your place on earth.