Snow Mold on Lawns

Given the amount of snow we received this winter and the fact that it remained piled up for a long time, usually on the lawn, I figured I would dust off this article with some identification, control, and prevention tips.

It is difficult to describe exactly what snow mold is but the best way for me to describe it is that it's a mysterious, almost web-like substance on top of the grass. It is typically more prominent in areas where there is more snow piled up.

Snow mold is a fungal disease that appears on lawns in early spring as the snow begins to melt and although it looks unsightly, really does not cause much damage to the overall health of a lawn. The problem that I run into when discussing snow mold with a client is that, although it is an easy problem to diagnose, there really is not a way to "kill" it, once it's been identified. I will try not to get off on too much of a tangent here, but, this is the same issue that I run into with a majority of our landscape diseases. In general, there are not too many products available to you, the homeowner, that will get rid of diseases. So what is a person to do?

Like most other diseases, the tips to "control" (for lack of a better word) snow mold are all preventative measures, so here are some tips to consider to try and prevent snow mold in the future.

Try to avoid over fertilization of lawns in the fall. While a good fall fertilization is always recommended to help get a lawn through the winter, too much grass growth can lead to longer grass blades and more blades laying over creating an ideal environment for the snow mold to get established. When fertilizing in the fall, a slow release nitrogen source is better because if you provide a flush of nitrogen when the grass is still growing it will encourage vegetative (blade) growth and not root growth which is what you are trying to promote with a fall fertilization

Continue to mow the lawn at the recommended height until it is no longer actively growing. This gets back to trying to prevent the matting down of tall grass blades preventing the ideal environment for snow mold growth.

Rake up leaves in the fall and manage the thatch layer. Decaying materials provide an adequate environment for fungal growth.

Spread out large snow piles to encourage rapid melting or use snow fence to minimize snow accumulation. I know this is much easier said than done, but it will help. Snow mold accumulates in areas where the snow has insulated the ground, not allowing it to freeze. Generally speaking, the mold will continue to grow as long as the conditions are favorable (moist and cool) and will usually disappear once the areas dry out a little and warm up.

In areas where there is a considerable amount of snow mold accumulation, it may be advisable to gently rake the area to help break up the matting of the mold and allow some air and sunlight in.

For more information about snow mold, I would encourage you to visit http://www.extension.umn.edu/garden/yard-garden/lawns/snow-molds-in-lawns and, as always, if you have questions about this or any other lawn and garden issues, feel free to give me a call in the Extension Office at 433-1206 or send an email to [email protected].