What You Need to Know About Fusarium & Snow Mould

As winter approaches and the days shorten so do the chances of Fusarium and snow mould rise. Fusarium and its close sister, snow mould, can cause unsightly patches of dead grass and prevent new growth from emerging. In this article, we will answer some common questions about these fungal diseases and provide tips on how to prevent and treat them.

What are Fusarium and Snow Mould?

Fusarium and snow mould are fungal diseases that can occur in cool, wet conditions. As the snow melts, it creates moist conditions that are ideal for the growth of snow mould. Fusarium is prevalent when you have foggy or misty weather along with short daylight hours. These diseases are extremely weather dependant so their appearance will be linked to this.

Can Fusarium or Snow Mould Kill Grass?

Fusarium and snow mould create a cobweb type mould on the lawn which quickly turns a mush. Unlike Red Thread, Fusarium actually kills the affected area and so will need reseeding in the spring.

What Causes Fusarium and Snow Mould on Grass?

Snow mould occurs when snow accumulates on lawns for extended periods. The moist conditions created by the snow provide a perfect environment for the growth of snow mould. Other factors that can contribute to the development of Fusarium include excessive thatch build up, poor soil drainage, and compacted soil. As with all fungi, it is often the way that the fungal spores are ever present just waiting for the right host and weather conditions to flourish.

Preventing and Treating Fusarium and Snow Mould

Preventing is the best course of action, and there are several steps homeowners can take to reduce the risk of these fungal diseases. These include:

  • Mowing the lawn with a sharp blade to prevent tearing of the leaf blade which can allow infection into the grass plant.
  • Raking up leaves and other debris before the first winter to reduce leaf litter.
  • Avoiding the overuse of nitrogen-rich fertilisers in the autumn, as this can encourage grass growth and make it more susceptible to Fusarium.
  • Improving soil drainage by aerating the lawn in the autumn.

If Fusarium has already developed, there are several treatment options available. These include:

  • Raking the affected areas helps dry out the grass and promote new growth. But be careful that you don’t unwittingly spread the spores. Sometimes it’s better to leave well alone until spring.
  • Applying a fungicide to prevent further spread of the disease.
  • Reseeding or returfing dead patches of grass if necessary.


In conclusion, Fusarium and snow mould are common problems that can affect lawns, however, you can take steps to prevent them, such as reducing thatch build up and improving soil drainage. If Fusarium has already developed and is not severe, it is best to renovate when temperatures warm in the spring. If it is severe, seek the help of an expert who may recommend fungicide.

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