William Powell Country

Charlara Dieback of Ash

Rural Matters

Article written by 15 November 2012

Chalara dieback of Ash has been reported at numerous sites across the UK. This is a serious disease of ash trees which is caused by a fungus called Chalara fraxina. This disease causes leaf loss, crown dieback and it can lead to tree death. The disease is particularly destructive in young plants, killing them in one growing season. Older trees can survive initial attacks, but tend to succumb eventually after several season of infection.

The Chalara fraxinea has caused large scale damage to the ash tree population in continental Europe since it was first reported inPolandin 1992. The first case in the UK was confirmed in a nursery in early 2012. These ash plants reportedly came from the Netherlands.  Since this time a number of other nurseries have confirmed the presents of infected trees. In addition to this there have been cases of Chalara fraxina in new plantations. All of these cases have been supplied by nurseries within the past 5 years.

In October 2012 Fera scientists confirmed a small number of cases of the diseases in ash trees which do not appear to have any association with recently supplied nursery stock. There are investigations into the possibility that the disease may have enteredBritainby natural means. These includes spores being carried on the wind, birds coming across the North Sea or on items such as footwear or vehicles of people who have been in infected sites in Europe.

The Forestry Commission have chosen not to close forests to public access and have advised owners of infected sites not to close as the risk of visitors spreading the disease appears to be very small.

The Forestry Commission are treating Chalara fraxinea as a quarantine pest under emergency measures. This means that they may use powers to contain and eradicate the disease when it is found.  Once a tree is infected it cannot be cured. It must be destroyed and removed from the woodland. Forestry Commission advice says that spores are produced from infected dead leaves between June and September. Spores are unlikely to survive for more than a few days and trees need a high dose to become infected. There is apparently low probability of dispersal of the spore on clothing, animals or birds.

Recognising Chalara Dieback

The forestry commission have produced a YouTube clip on how to identify Chalara fraxinea:


There are several ways of reporting the disease, ashtag.org has produced an app available on apple and android devises. This app gives guidance on how to identify the disease and report it.



Alternatively you can report suspected case by telephone or email to one of the following:

For England, Walesand Scotlandcontact either the Food and Environment Research Agency (01904 465625 or planthealth.info@fera.gsi.gov.uk) or the Forestry Commission (0131 314 6414 or plant.health@forestry.gsi.gov.uk)

For Northern Irelandcontact the Department of Agriculture and Rural Development (0300 200 7847 or dardhelpline@dardni.gov.uk)

The Forestry Commission have asked people to take the following precautions if they are visiting an infected or suspected wood:

  • Do not remove any plant material (firewood, sticks, leaves or cuttings) from the woodland
  • Where possible, before leaving the woodland, clean soil mud and leaves from footwear, bicycle wheels and tyres
  • Before visiting other countryside sites, garden centres and nurseries thoroughly wash footwear, bicycle wheel and tyres
  • Follow instructions on any signs


Will Robinson

Trainee Land Agent at JM Osborne Read more.

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