Snow mold is a type of disease that can affect unhealthy lawns. It is caused by fungi and is characterized by round patches, often 3 inches to 12 inches in diameter, of dead and matted grass. There are two types of snow mold - the Gray Snow Mold and the Pink Snow Mold. You can see them in the Spring when the snow melts, although the infection is often active in the cold fall and winter months.
Gray Snow Mold is easily identified by its white-gray color. When the grass dries in the Spring, it will leave tiny brown to black masses on the blades of the infected grass which slowly shrink and darken as they dry. Pink snow mold starts off as white patches, gradually maturing to a light pink color. They don't leave spots on the leaves as they dry.
In terms of severity, the pink snow mold is considered more severe because it affects not just the blades of the grass, but the crown and the roots as well. Grey snow mold on the other hand infects only the blade of grass. Pink snow mold can start to become active under cool and moist temperatures, even without snow. This means they can infect grass under the cover of trees as early as fall. Unlike gray snow mold which requires prolonged snow cover to thrive.
Both types of snow mold often go together. They remain inactive during the warmer spring and summer months. They thrive in conditions that are moist and cold, often growing extensively under the cover of moist thatch or snow.
While they make look awful and widespread, you should keep in mind that snow mold is easy to prevent and to treat with the proper lawn care tips. Yes, there are many things you can do to prevent snow mold. Take a look at these examples:
1. Mow your lawn regularly for as long as the grass is growing. The fungi that causes snow mold love really long grass. They are the perfect breeding ground for them. Cutting the grass religiously will help keep fungi from taking root in your lawn.
2. Do no leave grass cuttings on you lawn. These can pile up and cause thatching, which contributes to the ideal cool and moist environment for mold fungi to thrive. If you want to fertilize your lawn using the grass clippings, use mulched grass. Mulched grass are finer and decompose very quickly and don't contribute to thatching.
3. Rake fall leaves and do not let them pile up on your lawn. Mulch them if you wish to use them as compost but do not leave them lying on your lawn. Again, this creates a cool and moist environment that mold fungi just loves.
4. Time your fertilizer well. During fall, do not fertilize within 6 weeks before your grass "hibernates" for the winter. Especially avoid fertilizers that are rich in Nitrogen. Rich fertilizers applied too late will cause your grass to produce new growths which won't have enough time to go dormant for winter. These fresh leaves are the easiest target for winter damage and are the ideal host plants for mold fungi.
5. In winter, avoid piling snow on the banks of driveways or walk ways. Putting snow fences can also help prevent an accumulation of fresh wet snow on your lawn.
If in the spring, you find that you have snow mold in your lawn, do not fret. Rake away the dead and matted grass on your lawn to allow new grass to grow. You can repair the bare patches by sprinkling seeds evenly and grow new greens.
Fungicides are also available. It's the last option considered by many gardeners and homeowners and is only used in extreme cases. Most of the time, the application of preventive measures outlined here should be sufficient to control snow mold.