Forestry Commission logo

Action on ash tree disease Chalara dieback

This news story is now over a year old and information may no longer be accurate or up-to-date. It might also contain obsolete links.
Please use our search link on the left to look for more recent information.
Ash dieback disease (Chalara fraxinea) - developing lesion centred on a dead side

Issued jointly with Defra

The effort to address the ash tree disease Chalara dieback will mobilise the general public and focus attention on trees that show resistance to the disease as part of an action plan announced today by Owen Paterson, Environment Secretary in the UK Government.

Following an unprecedented effort across Great Britain to identify areas where the Chalara fraxinea fungus has infected trees in the wider environment, the Government this week brought together scientists, campaigners, charitable groups and woodland agencies to discuss what action should be taken.

The immediate plan of action was agreed at the Government’s emergency committee, COBR, which Mr Paterson chaired this morning. After the meeting, the Environment Secretary set out the Government’s objectives for tackling Chalara. These are to:

  • reduce the rate of spread of the disease;
  • develop resistance to the disease in the native UK ash tree population;
  • encourage citizen, landowner and industry engagement and action in tackling the problem; and
  • build resilience in the UK woodland and associated industries.

Mr Paterson set out an immediate plan of action to meet those objectives, building on the ideas discussed at the Chalara and Tree Health Summit on Wednesday 7 November. The advice of stakeholders, scientists and other experts at that discussion, agreed today at the COBR meeting, was that in the short term:

  • newly-planted diseased trees and diseased trees in nurseries will be traced and destroyed, as once young trees are infected they succumb quickly;
  • mature trees will not currently be removed, as they are valuable to wildlife, take longer to die and can help us learn more about genetic strains that might be resistant to the disease. Infection does not occur directly from tree to tree;
  • better understanding of the disease will be built through research and surveys, which will look not only for diseased trees but for those that show signs of genetic resistance to Chalara, to help identify genetic strains resistant to the disease;
  • the search for the disease will include trees in towns and cities as well as the countryside, building partnerships with a range of organisations beyond Government; and
  • foresters, land managers, environmental groups and the public will be informed how to identify diseased trees and those likely to be resistant to the disease, and know what to do if they find a diseased tree.

The Government has already introduced a number of control measures to reduce the speed of spread, which are in line with these recommendations. A ban on import and movement of ash trees into and around Great Britain remains in place. Immediate action is being taken to remove and destroy infected trees found in nurseries or in recently planted sites.

Where infection is found in mature trees, the scientific advice is to leave them where they are as infection does not spread directly between trees, but only via the leaf litter.

Speaking after the COBR meeting, Mr Paterson said:

“The scientific advice is that it won’t be possible to eradicate this disease now that we have discovered it in mature trees in Great Britain. However, that does not necessarily mean the end of the British ash. If we can slow its spread and minimise its impact, we will gain time to find those trees with genetic resistance to the disease and to restructure our woodlands to make them more resilient.

“The groups that put such a lot of effort into looking after our wildlife and our countryside will play a major role in minimising the impact of Chalara and so will the general public, especially when it comes to spotting other areas where the disease has taken hold.

“Our plans have been developed through bringing together Britain’s top experts and listening seriously to their advice. We now have a window of opportunity for action because the disease only spreads in the summer.”

Over the coming weeks the Government will work with scientific experts and other interested groups to further develop and implement the measures in the plan, and to set a longer-term approach to tackling Chalara. COBR agreed that this approach will also consider:

  • designating protected zones, to free up trade in ash from areas free of the disease through authorising businesses to issue “plant passports”;
  • establishing a tree health early warning network to provide advice, screening and initial diagnostics;
  • developing advice on protecting saplings, and responding rapidly if the disease is found;
  • developing advice on sustainable management of mature trees on sites affected by Chalara;
  • what additional equipment is needed to diagnose tree disease.
  • improved biosecurity including import controls; and
  • more public engagement in helping diagnose and tackle disease through “citizen science”, including an OPAL (Open Air Laboratories) citizen science project.

Details of the plan of action are available at

Information on Chalara, including videos and a photo guide explaining how to identify the disease, as well as details of confirmed cases in new plantings and the wider environment, can be found at