Chalara fraxinea – threat to Ash trees

Update 29.9.2019:

Latest information

The Forestry Commission has compiled updated advice for ash tree owners and managers in its leaflet, Managing ash dieback in England. (.pdf 3.8KB) The leaflet provides an introduction to the disease, summarises current advice, and signposts to more detailed guidance produced by Defra, the Forestry Commission and others. To request printed copies, contact


Chalara ash dieback is present in most parts of the United Kingdom. Its effects are most visible in regions where the fungus has been present for the longest time, and where local conditions are most suitable for the fungus.

You are not legally required to take any particular action if you own infected ash trees, unless your country forestry or plant health authority serves you with a Statutory Plant Health Notice (SPHN) requiring action. This is unlikely.

With the exceptions of felling for public safety or timber production, we advise a general presumption against felling living ash trees, whether infected or not. This is because there is good evidence that a small proportion will be able to tolerate H. fraxineus infection. There is also the possibility that a proportion of ash trees can become diseased, but then recover to good health. These, too, would be valuable for our research, although it is still too early to know whether there are such trees in the British ash population.

However, by keeping as many ash trees standing as possible, we can identify individuals which appear to survive exposure to the fungus and which can be used for breeding tolerant ash trees for the future.

For more information see here.

Update 19.6.2016:

The Forestry Commission map format has been changed again since my update in 2014 below.

“The shaded Ordnance Survey 10km grid squares show areas where Chalara dieback has been confirmed to be affecting ash trees in the natural environment. The presence of an infected site within a 10km square should be taken as indicative of a high likelihood that other ash trees/woodland in the same square may also be infected”.

It now shows that the outbreak referred to below had spread southwards in 2015 to include the 10km square centred on Fallowfield, which stretches from Didsbury in the south to the City centre in the north, and from Stretford in the west to Reddish in the east.

Update 29.11.2014:

I have now discovered that the Forestry Commission  “are using a new format of map to show where Chalara ash dieback has been found. The new map shows 10km x 10km squares in which Chalara has been confirmed”. This shows that in 2014 there has been one confirmed case in the 10 km square just to the North of Manchester city centre – see map here. This is the southern end of a new outbreak to the west of the penines. These cases are in the “wider environment”, e.g. established woodland.

They “no longer indicate recently planted sites with Chalara. The distinction has become less important because the diseased plants at many such sites have been removed and replaced, thereby eliminating the disease from the area, or the disease is present in the local wider environment anyway”.

This recent outbreak seems to cover a large part of Lancashire centred on Clitheroe, with 7 and 8 cases near the centre and down to 1 case in the 10km squares at the edges including North Manchester

The “ash-tagged” tree roughly in Chorlton Water Park referred to below is now “untagged”, whatever that means.

How to identify (including spring symptoms):

Update 21.10.2013:

A brief History of the disease:

Update 19.10.2013:

There have been a number of changes to the sites linked in my original posting below.

The Ashtag map I think now records any ash tree “tagged” not necessarily ones that are suspected as infected. The nearest one is still roughly Chorlton Water Park and I assume it was never suspected of being infected (as it does not appear on the Forestry Commission map of confirmed locations).

The Forestry Commision page has comprehensive information on the disease, including a map showing confirmed cases. NB: This map is now out of date (see above). The current version of this map is not as clear as the one in place on 16.11.2012

As of today the nearest Forestry Commission confirmed location in the “wider environment, e.g. established woodland” is to the south of Derby. This is about 25% closer than the nearest one a year ago (see below). The majority of the 225 places are in east Anglia, the South East of England and the east coast of Scotland.

The nearest Forestry Commission confirmed location in a recent planting is in the Huddersfield area, very slightly nearer to Manchester than a year ago.  There are 343 confirmed locations in new plantings, fairly evenly spread throughout the UK. I had presumed these were imported trees, but the Forestry Commission now reports 24 nursery sites have confirmed infection.

It is not clear whether these nurseries are included on the map as “recent plantings” or whether they are not recorded on the map. The first UK infection was found in a consignment of infected trees sent from a nursery in the Netherlands to a nursery in Buckinghamshire, in February 2012.

In March 2013 the government published a 37 page  National Plan for England (458 KB pdf download)

The video below gives very comprehensive instructions for identifying a suspected infection.

Original Posting:

Article from THE TIMES September 28 2012 (click on image to enlarge):

Update 16.11.2012:

How to identify (mainly before winter):

Suspected cases can be reported via the Forestry Commission’s Chalara helpline: 08459 33 55 77 (open 8am – 6pm every day)

The relevant Forestry Commission page is here

The University of East Anglia has produced a free ‘Ashtag’ app which makes it possible for anyone to take a photo of diseased leaves, shoots or bark and send it remotely to plant pathologists to identify whether or not the tree is infected.

As well as collecting photographic evidence, the app also uses geo-tagging software to give a precise location of infected trees – allowing researchers and authorities to build up a picture of where the dieback is happening. This can then be used to target areas for culling to stop the spread of the disease. (Underlining added)

People without a smartphone will also be able to join the campaign by uploading digital photos and location details direct to the AshTag website.

There is an interactive map here showing the latest information on the spread of the disease. Suspected sightings can be reported via this website.

As of 16.11.2012

There is one unchecked sighting apparently in Chorlton Water Park, but Ashtag say “Locations  shown in this map are imprecise to protect confidentiality”.

The nearest Forestry Commission confirmed location in a mature wild tree is to the north west of Hull.

The nearest Forestry Commission confirmed location in a new planting is in Hepworth, to the east of the Pennines, south of  Huddersfield. There are many other confirmed locations in new plantings. Presumably these are imported trees.

The Forestry Commission says: “Owners of any recently planted ash plants which are found to be infected, or infected ash plants in nurseries or garden centres, will be served statutory Plant Health Notices requiring them to destroy the plants, either by burning or deep burial on site, or to take steps to contain the disease on site” and “Unfortunately we are unable to offer compensation for plants destroyed to comply with a Plant Health Notice”.  (source).

This is in contrast to the compensation paid to livestock farmers in the various animal disease outbreaks. It would seem to be very unwise of the government not to institute a compensation scheme as it may result in inhibiting the reporting of suspected infections.

Many owners, especially of mature trees infected as a result of the unregulated import of infected saplings, will face large bills which they may be unable to afford. Ironically there could be panic removal of smaller healthy trees in order to avoid the risk of larger bills later on. This would of course also make it less likely for resistant trees to be found.

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