What is Pink Snow Mold and How Do You Get Rid of It?

large area of diseased grass from pink snow mold

​​Spring is almost here and the snow on the ground is finally starting to melt. But what are those pink patches of grass? While this discoloration shouldn’t raise the alarm, you don’t want to ignore the problem either. Those patches are a sign of the turfgrass disease pink snow mold.

The fungal disease can be an eyesore in the yard, and it can put stress on your turf. But by putting the proper treatments in place, you can green up your lawn in no time.

How to identify pink snow mold

When pink snow mold begins to develop in your yard, you might blink twice and think you’re seeing spots. Unless you’ve just hit your head, the spots you are seeing are probably a turfgrass disease. 

Infected pink snow mold develops well-defined circular patches that typically range from 2 to 10 inches in diameter. Some patches may merge to create large areas of affected grass. 

Patches of pink snow mold typically start small and enlarge as cold, wet weather persists. The patches appear gray, tan, or light pink and contain a white center. The grass within these patches is usually matted and has a pinkish hue. 

Another key symptom of pink snow mold is the white-pink, fluffy mycelium that develops on the infected grass in wet conditions. 

What grass types are susceptible to pink snow mold?

Pink snow mold is unlikely if you grow a warm-season lawn, such as Zoysiagrass or bermudagrass. The disease infects nearly all cool-season turfgrasses. Annual bluegrass, fescue, perennial ryegrass, and creeping bentgrass are the most susceptible turf types. Kentucky bluegrass and fine-leaved fescue are the least susceptible. 

What causes pink snow mold?

The fungus that causes pink snow mold is called Microdochium nivale. Symptoms occur in late winter or early spring but also can appear in late fall if conditions are right. The disease prefers temperatures between 30 and 60 degrees Fahrenheit. Although pink snow mold usually infects the leaves, a severe Microdochium nivale infection can rot the crowns and kill the turf. 

Disease development occurs on the unfrozen ground underneath deep snow covers that remain on the turf for a long time. The longer a deep snow cover remains, the longer the disease is exposed to favorable temperatures and the snow’s insulating effects, leading to a more severe infection. It isn’t until the snow has melted away that you’ll first notice signs of the disease. 

Pink snow mold can still develop during long periods of cold and wet conditions, even without a snow cover. When pink snow mold occurs without a snow cover, it’s often referred to as Microdochium patch.

But you don’t need to live in the North Pole to get this disease growing in your yard. Although cold conditions are essential for the disease to develop, how you maintain your lawn also affects the success of pink snow mold. 

Your lawn may be susceptible to pink snow mold if it has: 

  • Tall grass
  • High levels of nitrogen fertilizer
  • Poor soil drainage
  • Grass seed planted in the fall that did not mature before winter
  • Excessive thatch 

How does pink snow mold spread?

Pink snow mold thrives in cold and wet conditions, particularly when underneath a snow cover. The mycelium spreads from plant to plant and creates new infections. Wind, people, lawn equipment, animals, and water disperse the spores to other yard areas.

Pink snow mold reverts to dormancy when dry, warm weather returns. The pathogen Microdochium nivale remains dormant in thatch, infected grass, and leaf litter until favorable conditions arise in late fall, winter, and early spring. 

How to get rid of pink snow mold

Watching your front lawn’s beautiful blanket of snow be replaced by pink mold isn’t the most exciting way to head into spring. 

But never fear: As the temperatures begin to rise and the wet turf dries, pink snow mold will slowly start to fade. When you combine the drier weather with the following treatment methods, pink snow mold should clear up in no time. 

Ready to get your green lawn back? Here’s what you need to do: 

  • Remove piling snowdrifts. If you let a snow cover stay on your lawn for too long, you’re encouraging a breeding ground for the fungus. 
  • Rake the affected areas to break up matted grass, remove excess thatch, and increase air circulation. 
  • Avoid applying high levels of nitrogen fertilizer. Remember, pink snow mold loves high nitrogen levels. 

How to prevent pink snow mold

After treating your lawn for pink snow mold, you’ll never want to go through that hassle again. The good news is that you can perform lawn care measures to help prevent the disease from recurring. This might mean putting a little extra effort into your lawn care routine, but at least it means less time sweating over fungus. 

  • Avoid heavy nitrogen fertilizer applications in the fall.
  • Mow until late fall to avoid snow covering tall grass. Remember to keep the mowing height low, but not so low that you scalp your lawn. 
  • Remove snowdrifts that pile up on your lawn. You can help reduce snowdrifts with strategically placed snow fences and wind barriers. 
  • Overseed the lawn with grass varieties resistant to pink snow mold.
  • Remove excess thatch from the lawn.
  • Rake up the autumn leaves.
  • Reduce snow compaction caused by skis and snowmobiles. Compacted snow can take a long time to melt. 
  • Apply a fungicide (such as azoxystrobin, iprodione, or propiconazole) as a preventative treatment in the fall. Fungicide applications are not helpful as a curative treatment against snow mold. 

FAQ about turfgrass disease

1. How do I prevent turfgrass disease?

Pink snow mold isn’t the only fungal disease that can infect your lawn. If you’re concerned about other lawn diseases destroying your turf, you may need to make several lawn care adjustments. 

Turfgrass diseases often infect stressed, weak lawns. That’s why the best way to prevent fungal growth is to preserve your lawn’s health and keep it well maintained. 

The following lawn care treatments are excellent ways to encourage a strong lawn that’s resistant to disease. Showing your yard some TLC takes time and energy, but in return, your lawn gives you a stunning, fungus-free landscape. 

Remove leaves and other debris from the lawn. Lawn debris provides the perfect shelter for fungus to remain dormant. 

Mow the grass regularly (and correctly). Don’t cut more than ⅓ of the grass blade at a time. Cutting too much at once will stress and weaken the turf. Don’t mow so low that you scalp the lawn, but don’t let the grass grow too tall either. 

Leave behind grass clippings. A layer of grass clippings acts as mulch by retaining moisture and adding nutrients to the soil. However, when a fungal disease is infecting your grass, you don’t want to leave the grass clippings on the lawn (otherwise, the infection may spread). 

Perform proper irrigation practices. Many fungal diseases thrive in long periods of leaf wetness. Water at the right time of day to minimize a wet environment on the lawn. The best time to water the lawn is before 10 a.m. Avoid watering the grass in the evening; otherwise, the water will remain on the grass overnight and invite pests and disease. 

Invest in a sprinkler system. If maintaining a watering schedule proves difficult, an automatic sprinkler system may be just what you need. A sprinkler system applies uniform water levels across the yard and meets your lawn’s exact moisture needs. 

Plant grass seed that’s disease-resistant and suitable for your lawn. The grass type you plant in your yard should be compatible with your local climate. Talk to a local lawn care professional about the best grass types to grow in your area, including disease-resistant varieties. If you don’t plant a grass type suitable for your lawn, it will struggle to grow. 

Test your soil and add amendments. Healthy grass needs healthy soil. Conduct a soil test to determine what nutrients are missing from your soil. 

Fertilize your grass. Many turf diseases prefer lawns that have unbalanced fertility levels. Create a fertilization regime that gives your turf the right level of nutrients at the right time of year. 

Aerate compacted soil. Compacted soil weakens your lawn by preventing oxygen, nutrients, and water from reaching the roots. An aerator creates small holes in the ground to relieve compaction. 

Remove thatch that exceeds ½-inch thick. Thatch is the dead organic matter that accumulates between the soil and turf. Several fungal diseases will remain dormant in a thick thatch layer. 

Overseed the lawn. The secret to maintaining a dense, green lawn is routine overseeding. If you don’t plant new grass seed, your yard will begin to thin and develop patches.   

Remove existing weeds. When too many weeds grow in the yard, your turf will need to compete for nutrients, sunlight, moisture, and space. Relieve your turf from this stress by removing weeds with a post-emergent herbicide or hand pull them. 

Apply pre-emergent herbicide. Post-emergent herbicides target existing weeds, while pre-emergent herbicides help prevent weeds from establishing. 

Control grubs and other pests. Grubs live just underneath the soil’s surface and munch on your turf’s root system, causing the grass to weaken. 

Spread a ½-inch layer of compost across the lawn. Compost provides a nutritional boost for the yard. You can spread a compost top dressing with a rake or brew a compost tea and spray it on the lawn.  

Chemical control: Fungicide treatments are often more effective as preventative measures than curative measures. If your lawn experiences frequent fungal infections despite enhanced lawn maintenance, then applying a preventative fungicide may be helpful. 

2. What other grass diseases can infect my lawn?

Removing thatch, mowing the lawn, spreading fertilizer –– which lawn diseases will these treatments help prevent? The healthier the lawn, the more resilient it can be against diseases, including: 

Brown patch
Dollar Spot
Fairy ring
Gray snow mold 
Leaf spot and melting-out 
Powdery mildew
Red thread 
Summer patch

3. What if I can’t identify the fungus on my lawn?

Identifying the fungus growing in your grass isn’t always easy. Some lawn grass diseases resemble similar symptoms, and some diseases can only be diagnosed with a microscope. 

Correct identification is essential. If you misidentify the fungus, then you might implement treatment methods that don’t affect that particular fungus. The infestation may grow more severe and potentially kill your turf. 

If you can’t identify the lawn disease, turn to a diagnostic lab or turfgrass pathology lab for help. These labs specialize in diagnosing turfgrass diseases. You can likely find one at your local state university. 

Leave pink lawns to the pros

Raking pink snow mold out of your lawn is probably the last way you want to spend your weekend. While the family is playing games inside, your weekend priority is… fungus? If treating fungus doesn’t sound like a weekend well spent, hand the job over to the pros.

Hire a local lawn care professional to tackle the job for you. Better yet, a pro can help prevent lawn disease year-round with weekly mowing, fertilizer applications, and thatch removal. A pro can keep your lawn healthy and fungus-free for you. 

Main Photo Credit: Bevegelsesmengde | Wikimedia Commons | CC BY-SA 3.0

Jane Purnell

Jane Purnell is an artist, writer, and nature lover. She enjoys teaching readers about the importance of eco-friendly lawn care, integrated pest management, biodiversity, and sustainable landscaping.