Woodland Trust

Nature's CalendarNature Detectives

Have you spotted the first flowering of elder yet?

Bleeding cankerforestry.gov.uk

What is it?

  • Horse chestnut tree trunks and branches begin to ooze a brown sticky substance as a result of a bacterial infection

  • The bark then splits and the tree itself becomes progressively sicker (eg with fewer or prematurely yellowing leaves) as the years progress

  • This is because of the increasing bark damage. If the bark is killed around the full diameter of the trunk, the tree will die

  • Some infected trees do however appear to recover

  • This disease has been known in the UK since the 1970s but is becoming increasingly widespread with the latest Forestry Commission estimate suggesting 49% of trees are now infected UK-wide.

More information

Advice for recording leaf tint etc. with us

It may be possible to find trees in your area that are not yet infected or only in the early stages of disease and record these. Avoid recording trees that are obviously dying.

How to report that your local trees are infected 
Forest Research (the department of the Forestry Commission that researches tree diseases) is not actively asking the public to help monitor this disease, as it is already so widespread.

Infected tree management advice