Information for those who own or manage ash trees, including private tree and woodland owners as well as local authorities.
Applies to England
Most parts of the country are now experiencing the impacts of ash dieback. The disease is causing widespread decline of ash trees in some areas and this is expected to continue. It is likely that the majority of our native ash trees will exhibit symptoms of ash dieback, but not all that do will die. A small percentage of ash trees will have a degree of tolerance to the disease and others will exist in locations where they escape the worst impacts.
It is important that the effects of ash dieback are planned for and managed, especially in safety-critical locations. The following guidance is intended for anyone who owns or manages ash trees, including private tree and woodland owners and local authorities.
Ash dieback is fungal disease affecting the common ash tree (Fraxinus excelsior) and other Fraxinus species. It is caused by a fungus called Hymenoscyphus fraxineus which is native to eastern Asia. The disease was first identified in England in 2012, although research has shown that it is likely to have been present since at least 2005.
Ash trees are common in woodland and non-woodland settings. They make up 12% of Great Britain’s broadleaved woodland, and are often found in parks, gardens, hedgerows and roadside margins. Ash dieback is present in most parts of England, although the severity of the disease varies locally. Local conditions will determine how ash trees are affected by the disease. Trees in woodlands with high proportions of ash are likely to decline more quickly due to higher inoculation loads.
There is some evidence that ash trees growing in open, less humid locations such as streets and hedgerows may deteriorate more slowly or persist indefinitely, although it is not yet clear whether this will be a consistent pattern. Some trees with few symptoms could survive on these sites for many years, and a small proportion of trees may have a degree of genetic tolerance to the disease.
Identifying ash dieback
Infection can lead to leaf loss and dead branches throughout the crown of ash trees, and clumps of new growth towards the centre of the crown.
In areas of high infection, the fungus can cause lesions at the base of the tree, making it more susceptible to secondary infections, such as by Armillaria fungi.
For signs and symptoms, including images visit:
Videos on how to identify ash dieback can also be found on the Forestry Commission’s YouTube page.
People who manage ash near roads, railways, buildings and other publicly accessible land must consider the risks posed by infected ash. Trees or woodlands in these areas should be risk-assessed, monitored and managed to reduce the risk. By law, the owner of land where a tree stands is responsible for the health and safety of those who could be affected by that tree. If you are unsure about health and safety risks, consult a fully insured tree management professional who holds a relevant qualification.
To find out about your responsibilities as a tree owner see:
Dead or dying ash also poses a risk to professionals working on or near them. Further information is available for landowners and forestry managers:
- Essential information on the felling of diseased ash – UK FISA
- Ash dieback: practical guidance – Arboriculture Association
Guidance for land managers and tree owners
It is important to consider the effects of ash dieback if you own or manage ash trees, even if you are dealing with low levels of infection. Felling diseased ash requires a felling licence from the Forestry Commission, unless the trees are dead or pose a real and immediate danger. Restrictions such as tree preservation orders must also be respected. Your local authority will be able to provide guidance.
Some ash trees may have genetic tolerance to ash dieback, meaning they may survive and reproduce to create the next generation of ash trees. Therefore, it is important to retain ash trees where they stand out as being healthier than those around them and it is safe to do so. Retaining a proportion of dead, dying or felled trees will provide deadwood habitat and be beneficial for biodiversity.
If you are responsible for managing ash in woodlands, see:
If a site is subject to a designation such as Site of Special Scientific Interest (SSSI), or might contain European Protected Species, additional rules apply. See guidance from the Forestry Commission and Natural England:
If you are responsible for individual or small groups of ash trees infected by ash dieback, see:
- Managing ash trees affected by ash dieback: operations note 46a – Forestry Commission
- Ash dieback tree owners’ guide – Tree Council
Additional guidance is also available from the Tree Council for local authorities on preparing an action plan:
Replacing trees lost to ash dieback
Replacing trees felled due to ash dieback is important for minimising the impact of the disease. The species chosen should be well suited to the current site conditions, and those likely to be seen in the future due to climate change. Where large numbers of trees are being planted, using of a range of appropriate species will help to lower the risk of future disease events having such a severe impact.
For guidance on restocking woodland, see:
- Restocking woodland following loss of ash due to ash dieback: operations note 46b
- Right trees for a changing climate database (for trees in urban areas) – Forest Research
- Ecological impacts of ash dieback and mitigating methods – Forest Research
Where a felling licence is granted, you will need to restock the area where trees were removed. Countryside Stewardship grants are available to help with the costs of this in woodland.
Support in 21/22 is available for local authorities to create resilient treescapes through the Local Authority Treescapes Fund. Up to 50 grants worth between £50,000 and £300,000 will target landscapes that have been neglected in the past, ecologically damaged or affected by tree diseases like ash dieback.
This guidance is summarised in a leaflet:
More information on ash dieback, including signs and symptoms and research can be found on the Forest Research website: