Policy paper

Chalara management plan

Chalara dieback of ash trees is caused by the Hymenoscyphus fraxineus fungus, formerly known as Chalara fraxinea.

This was published under the 2010 to 2015 Conservative and Liberal Democrat coalition government


Chalara management plan

This file may not be suitable for users of assistive technology. Request an accessible format.

If you use assistive technology (such as a screen reader) and need a version of this document in a more accessible format, please email defra.helpline@defra.gov.uk. Please tell us what format you need. It will help us if you say what assistive technology you use.


Ash tree dieback is caused by the Hymenoscyphus fraxineus fungus (previously known as Chalara fraxinea). It has already affected a high proportion of ash trees in Northern Europe.

It was discovered for the first time in Great Britain in a nursery in Buckinghamshire in February 2012. In October 2012, it was also found in the wider environment in woodland in Norfolk.

The scientific advice is that we can’t stop Chalara but we can focus on reducing the rate of its spread. However, this plan ;

  1. provides an update on the action Government and others have already taken in response to the disease;
  2. Sets out new science-based and proportionate action that will be taken now that our understanding of Chalara, and the costs and benefits of action has developed further; and,
  3. Outlines further work that will be undertaken to further develop our understanding of the disease.

This plan is an update to the interim control plan that was published on the 6 December 2012.

The Management Plan sets out action around four key objectives:

  • Reducing the rate of spread of the disease
  • Developing resistance to the disease in the native ash tree population
  • Encouraging  landowner, citizen and industry engagement in surveillance, monitoring and action in tackling the problem
  • Building economic and environmental resilience in woodlands and in associated industries

The actions announced in the Plan includes research into resistance to Chalara, outlines funding to assist landowners with replanting of diseased newly infected young ash trees, details how we are working with  engaging with citizens, landowners and industry on surveillance, monitoring and action in tackling Chalara, and details on build economic and environmental resilience in woodlands and in associated industries.

  • In Spring 2013 the independent Tree Health and Plant Biosecurity Expert Taskforce convened by Defra’s Chief Scientific Adviser, Professor Ian Boyd will be publishing the Final Report of the Independent Tree Health and Plant Biosecurity Expert Taskforce that will look at ways to prevent pests and diseases from entering the country in the future.
  •  Below are links further details on research that is being commissioned and other evidence sought as we continue to improve our understanding of Chalara, how it spreads, and how spread might be slowed and damage reduced.   This research forms part of the overarching tree health and plant biosecurity evidence plan. Also published today a project by the Forest Research (the research agency of the Forestry Commission in conjunction with many collaborating land-owners and nurseries to identify those few ash trees which might be resistant to Ash Die Back.

Further information

Published 26 March 2013
Last updated 9 April 2019 + show all updates
  1. Updated the page to reflect that the name of the fungus has changed from Chalara fraxinea to Hymenoscyphus fraxineus fungus.

  2. First published.