Information sources on ash dieback

Are you concerned about the spread of ash dieback and the impact on our landscape?

Chalara fraxinea (C. fraxinea), or ash dieback, is one of the most significant fungal pathogens to be introduced to Britain in recent years, and its spread represents a major challenge to the management of our woodlands in Cumbria. As well as important ash woodlands, there are significant numbers of individual ash trees in our farmed landscapes.

The disease causes leaf loss, crown dieback and bark lesions in affected trees. It is usually fatal, either directly, or indirectly by weakening the tree to the point where it succumbs more readily to attacks by other pests or pathogens.

It has caused widespread damage to ash populations in continental Europe.  Between 60 and 90 per cent of Denmark’s ash trees in forests are affected by the disease. Outside forests it's a different story. Here the percentage of affected ash is much lower.  Experience in other parts of Europe indicates that it can kill young ash trees very quickly, while older trees tend to resist it for some time until prolonged exposure, or another pest or pathogen attacking them, eventually causes them to succumb.

Local spread, up to some tens of miles, may be by wind. Over longer distances the risk of disease spread is most likely to be through the movement of diseased ash plants.
Ash trees suffering with the infection have been found widely across Europe since trees were first reported dying in large numbers in Poland in 1992. These have included forest trees, trees in urban areas such as parks and gardens, and also young trees in nurseries.

View Advice for Land Managers and Advisors on Ash Dieback

View information on what can we do about Ash Dieback on woodland Sites of Special Scientific Interest (SSSI)

We have collated some useful links and information from around the web that should provide you with help. The video and first few links are provided as general advice and information, and then further down the page are links to more specific resources and academic papers on chalara's impact.

The Royal Botanic Garden, Edinburgh have published a beautiful animation on YouTube describing the importance of Ash in Scotland and the likely response (the content is entirely relevant to ash in England and Wales).

Many thanks to The Royal Botanic Garden, Edinburgh for allowing us to publish this video on our site.

Forest management with ash dieback, experience from Denmark (some points from Iben Margrete Thomsen's presentation, Cumbria Woodlands’ ash conference 1/11/2017)

  • The much-quoted statistic (in the UK) that >90% of Denmark’s ash trees have been killed by ash dieback is WRONG! In fact, 90% of Denmark’s ash trees in forests show signs of infection, but it is mainly young stands that die. For ash trees outside forest settings (e.g. park land, urban, pasture) the situation is quite different, as only a small proportion are severely affected, and large old trees cope well with the disease.
  • This vulnerability of woodland ash is because the conditions in (cool, moist) are more conducive to ash dieback infection, and because of the presence of honey fungus, which often kills the trees as a secondary infection.
  • Young trees are by far the most at risk. This is because of their smaller girth and thinner, smoother bark, which is more vulnerable to infection around the root collar.
  • Once a forest tree is affected by ash dieback, it will cease to add any significant girth to the trunk, because all its energy will go into replacing the canopy and fighting honey fungus.
  • Diseased trees may be left standing, but once epicormic growth appears on the main stem/trunk, the fungus will rapidly enter and stain the wood of the trunk, causing economic loss for the forest owner.
  • The initial rate of death from the infection throughout the UK may seem rapid and alarming. This is because the young and highly susceptible trees will die, and trees that are already stressed succumb fast. Trees avoiding this initial wave may linger for decades, and this will give woodland managers some breathing space to initiate strategies for replacement of affected ash trees and stands.
  • In order to identify truly tolerant individuals, it is necessary to allow for at least 10 years of incessant infection pressure. Before this time, trees may show a varying degree of tolerance, but most will eventually develop dieback symptoms and decline. It is important to retain ash stands until the few percent truly tolerant trees stand out, so they can be selected for breeding.

Forestry Commission
The Forestry Commission have provided a comprehensive guide to chalara, including the latest on its spread in Great Britain. They have also published a leaflet including information specific to the north west of England.

The Joint Nature and Conservation Committee have put together a Pdf poster identifying ‘important ash in Great Britain', available in our downloads section.

The Guardian collated a summary of the ash dieback situation in April 2014. 

The RHS (Royal Horticultural Society) have a page of guidance on their website, including a list of other pests and diseases of ash and their symptoms.

Royal Forestry Society (promote the wise management of trees and woods) have published a guidance note on their website.

FERA (Food and Environment Research Agency)
The Government Animal & Plant Health Agency have published a page describing Fera’s work on Ash Dieback, including a shortlist of products for testing against chalara, a helpline/email contact, a selection of videos on chalara history, life-cycle and symptoms, and some symptom photos: FERA chalara
A link to download the Government’s Chalara Management Plan is here

The Joint Nature Conservation Committee have commissioned several scientific publications in the face of chalara spread. These include:
The potential ecological impact of ash dieback in the UK (link to summary of paper and access to download the publication)
Ash dieback: long-term monitoring of impacts on biodiversity (link to summary of paper and access to download the publication)
The distribution of important ash in Great Britain.pdf

Inspiring advances in the science and practice of sustainable forestry, Prof. Edward Wilson MSB, silviculturist, has many publications on ash management and chalara. Here is a selection of his publications, available on the web:

A general presentation which includes many ash images is here on  Edward’s team at Silviculture Research International have delivered a citizen science project focused on ash dieback, funded by the Heritage Lottery. Among the outputs has been a citizen engagement publication highlighting the importance of ancient ash trees in the Eden Valley. The resulting publication aims to increase awareness of the disease. This link on researchgate allows you to download the e-book (cancel the pop up window and download – no need to sign in).  

Edward also produced a paper (.pdf in our website's downloads section) and presentation in June 2014 (based on Forestry Commission best practice at the time) “Silviculture and management guidance for ash trees and woodlands”, available here on slideshare.  The second associated presentation, also on slideshare, covers biology and includes many Cumbria-specific pictures. 

Living Ash Project
A presentation on chalara and its impact, including examples and photos of key Borrowdale valley ash specimens: