Horse chestnut canker

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Horse chestnut canker (Photo: WTML)

Bleeding horse chestnut cankers were first reported in Britain in the 1970s (Photo: WTML)

This disease was first reported in the UK in the 1970s but was relatively uncommon until around five years ago.

What is horse chestnut canker?

A new strain of horse chestnut canker has seen cases surge across the UK, affecting trees of all ages and spanning from the south of England to the north and Scotland.


  • Extensive bleeding areas on tree stems
  • Occasional bleeding areas on scaffold branches


  • Linked to a bacterium species known as Pseudomonas syringae pv. aesculi
  • Mild winters and wet springs perhaps worsened symptoms in recent years


  • Large, mature trees can be disfigured by the disease
  • In severe cases large old trees can die
  • Younger trees are at greater risk and can die within 3-5 years

Report it

If you think you’ve spotted this disease please inform the Forestry Commission using the Tree Alert reporting tool. Three good-quality digital photographs are required to aid identification.

For more information visit the Forestry Commission.

Trees face huge challenges

With more new pests and diseases reaching our shores tackling pests and diseases is now an urgent priority

Learn about the threats