Is This White Mold On My Grass ‘Snow Mold’?

As warmer temperatures arrive in the Rockford area the snow melts and new life begins to sprout. We start to see early spring flowers and other hardy perennials.

For some of us, though, another form of growth has taken place over the winter. With the snow cover dissipating, you may notice a form of white mold clinging to the blades of grass in circular patterns across your lawn. What is this lawn disease? What causes it? And perhaps of foremost concern, what can you do about it?

What is snow mold?

Snow mold is a type of fungus that can potentially take a healthy lawn and cause severe damage. The mold typically concentrates in straw colored circles 3″ to 12″ in diameter, although at times these areas can be much larger, overlapping spaces.

There are two different types of snow mold: pink (Microdochium nivale or Fusarium patch) and gray (Typhula spp. or Typhula blight). Gray snow mold is less damaging than pink, as it tends to target only the grass blades while pink mold can destroy the roots and crowns of grass.

Common hosts include cool season grasses like fine Fescue, tall Fescue, creeping Bentgrass, annual Ryegrass, perennial Ryegrass, and Kentucky Bluegrass.

What causes snow mold?

Snow mold is typically found in areas that see extensive snow cover, the cooler regions of the Northern Hemisphere.

The disease often begins in October or November, but the pathogenic spores can also survive in semi-dormancy over the warmer months of spring and summer. During this time, they’re growing and spreading via wind, rain, and traffic.

What to do about snow mold?

Based on the previous information, you may realize that you indeed have snow mold growing on your grass. If so, what can you do to fix it?

There is no fungicide that has proven effective against snow mold as it presents itself in the spring. The best means of defense is to prevent snow mold from ever happening through good lawn care habits. Here are our top tips:

  1. Keep your grass fairly short before the first snow of the season. Of course, you don’t want to cut it too short as this can also be damaging. Cutting your turf to 1.5″ to 2″ is ideal.
  2. Avoid a thatch layer. It’s a perfect breeding ground for disease. We recommend using a hand or power rake to remove excess grass clippings and leaves.
  3. Do not over-fertilize. Too much nitrogen in the fall will exacerbate snow mold by encouraging growth late in the season. If you choose to fertilize, opt for a slow-release lawn food.
  4. Prevent snow piles, if possible. Snow mold loves shaded areas and snow cover. The longer the snow takes to melt, the more likely the mold is to form.
  5. Ensure adequate drainage. We have written an article that describes 4 popular drainage solutions.
  6. While fungicide will not be effective in the spring, it can be helpful when applied in the fall. This is especially so if your lawn has a history of snow mold. It is a good idea to apply fungicide after your last time mowing and prior to the first significant snow of the season.

You may now be thinking, “That’s all well and fine. But it is March, not October. What can I do right now to fix this problem?”

The first thing we recommend is to gently loosen any matted grass with a rake. This improves airflow to the affected area and encourages new grass to grow. If your lawn has a serious thatch problem, it may be a good time for heavier dethatching. And spring is an ideal time for this!

In severe cases, reseeding may be necessary. You can do this with a patching product as soon as the weather permits.

Another thing people have tried is solarizing the damaged patches (covering them with clear plastic on a sunny day). This will allow the heat from the sun to kill the disease and give you a clean slate to reseed. If you don’t care for chemical treatments, garlic and neem oils or an iron sulfate solution are natural antifungals.

Call M2 Landscaping for help

Snow mold can put a damper on the spring sunshine, but it doesn’t have to ruin the season. At M2 Landscaping, we want you to enjoy your home and outdoor living spaces. We would be happy to discuss your specific lawn and landscape maintenance needs. Give us a call today!