Ash dieback and other threats

Ash dieback is a highly infectious disease affecting ash trees.

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The latest information from the Forestry Commission shows that ash dieback has now taken hold across much of the UK, including Leicestershire.

What is ash dieback?

First confirmed in Britain in 2012, ash dieback is a disease of ash trees caused by a fungus called Hymenoscyphus fraxineus. A high proportion of ash trees in Northern Europe have been infected and the disease is now widespread in England.

Ash dieback is evident in ash trees in parts of Leicestershire and the National Forest. The fungus is spread by the wind or by the movement of diseased ash trees.

There are no exact figures of the number of ash trees in Leicestershire, but it’s estimated there are over 500,000 in the county.

The long term impact of ash dieback is likely to be:

  • loss of up to 90% of ash trees, with significant long-term impact on our woodland landscapes
  • probable replacement of ash woodland by scrub and other tree species
  • an associated loss of biodiversity
  • dying trees (that can become a danger) and the need for replacement trees
  • loss of trees can also impact on flooding and climate change

It won’t be possible to eradicate the disease, but along with other landowners and agencies, we can all play a part in helping to minimise the impact.

As a landowner, what can I do to help manage ash dieback?

It's vital that everyone who has ash trees on their property takes action to ensure they are safe.

As a landowner, you should try to:

  • retain ash trees where possible, including existing (healthy) ash trees so that more tolerant individuals can be identified to provide stock for the future
  • check for signs of ash dieback regularly
  • have their trees regularly inspected by a professional
  • minimise any pruning or tree surgery, as young regrowth is more susceptible to the disease
  • keep an eye on the tree’s safety as the disease progresses. If you are a landowner, you are responsible for managing the health and safety risks from dead and dying trees on your land
  • pay particular attention to ash trees within areas where the failure of the whole tree or falling branches could place people or neighbouring property in danger
  • monitor trees near highways and rights of way or areas with high levels of public access for signs of the disease, and if risk assessments show these as a hazard, plan careful pruning or felling
  • consider planting other species appropriate to the location
  • familiarise yourself with Forestry Commission information
  • take a look at the Tree Council guidance

How do I spot an infected tree? 

  • The most visible sign that a tree is infected is bleeding sores and cankers on the bark, and discolouration of the underlying sapwood.
  • The sores often surround branches in the infected area of the tree, causing the dieback of shoots, twigs, branches and smaller stems.
  • The disease has also been shown to infect ash tree leaves, appearing as blemishes.

There are numerous other diseases that display similar symptoms, making it difficult to identify for most people.

You can find pictures of infected trees and leaves in the Forestry Commission’s leaflet (see above).

Ash dieback affects young trees and new regrowth most severely, so it’s likely to be several years before it causes structural problems in mature trees.

What about trees close to a road, path or railway?

You might be concerned about a tree that is by a road or path and poses a risk. You should make the landowner aware in the first instance. Hedges and trees in general, are the responsibility of the adjacent landowner, although a small proportion are owned by Leicestershire County Council.

If tree and hedge issues by a road or path are reported to us, we will find out who is responsible and ask them to cut back the trees within a reasonable timescale. If the work is close to a road or path, and the landowner doesn’t carry out necessary work, we may arrange to undertake the work ourselves and recharge them.

If the tree that you’re concerned about is close to a railway – contact Network Rail.

What is Leicestershire County Council doing?

We launched our Ash Dieback action plan in July 2018. The plan outlines what steps we’re taking to manage the disease.

Where can I find out more about ash dieback? 

The Forestry Commission’s website has further information.

Other threats

Ash dieback is not the only threat to our trees and woodlands. Please find more information about pests and other diseases on the Forest Research website.