Snow Mold Prevention and Treatment
Snow mold can cause problems in late winter when there is snow compacting turf. Learn more about how to prevent this from happening and ways to treat the fungus.
March 1, 2022
Snow mold is a type of fungus, stemming from the Microdochium nivale fungus, that mimics the look of snow and affects grass while snow melts. It can be gray, white, or pink and can grow on any cool season turfgrass.
These spores live in the turf year-round, but are only active when the temperature is around 30-60˚F, and usually become visible between 32-45 ˚F. It causes grass to die, leaving the turf splotchy with the mold itself and/or dead spots where the mold has killed the grass.
Some grass, like bentgrass, is more susceptible to snow mold. Kentucky bluegrass is moderately affected, while fine fescue is more resistant to the fungus.
There are two kinds of this fungus. The pink snow mold, or Fusarium patch, ranges from white to pink. Gray snow mold, or Typhula blight, is gray-white.
- Mow the turf regularly, but especially before snow. Cut the turf shorter than normal before expected snowfall so the grass will retain less water; taller grass can mat down and trap moisture. Do not leave trimmings on top of the turf.
- Dethatch your customer’s turf at least twice a year.
- Ensure the area has proper drainage installed before the winter season. Ponding can create the perfect spore breeding ground
- Rake any leaves before they get wet, or they will trap moisture. When possible, remove snow from the turf. Additionally, if you shovel or blow snow off the pathways and sidewalks, ensure the piles of snow are not too large, as larger piles take much longer to melt.
- Apply a preventive fungicide like LESCO Drax. This should occur in late fall before turf growth completely stops.
- Follow a fertilization plan for your area, but do not fertilize with nitrogen in late fall. Cool-season grasses go dormant in winter, making them less susceptible to snow mold as their blades become dehydrated. With fertilization late in the season, this process gets disrupted, and the nutrients can create a welcome environment for the spores if not absorbed by the turf.
- Fertilize in the spring to encourage new growth.
- Prune or remove large trees that shade the turf to improve air and light circulation.
While the best treatment is prevention, sometimes snow mold is unavoidable. It typically goes away on its own in the spring once the temperatures warm and soil dries. Take care of this fungus with the following tips:
- Rake over the affected areas gently. This will help get airflow through the blades and help them dry more quickly.
- Reseed the patches where turf has died if regrowth does not occur.
- Avoid further fungicide and fertilizer application until these patches grow over.
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