Ash Dieback Disease – what is it and how do we recognise it?

by fse-admin - / 05.08.2015

There has been a fair amount of coverage in the press about the appearance and control of ash dieback disease since its appearance in the UK in 2012. Once trees are infected, the disease is usually fatal and it has already caused the loss of ash trees across mainland Europe.  Sadly now, more cases have been found in Britain.

What is ash dieback?

Ash dieback disease is caused by a fungus known as Chalara fraxinea which was found in the UK for the first time in 2012 in imported young ash plants at a nursery in Buckinghamshire.

The disease is characterised by the premature loss of leaves from the outer parts of the tree crown (top and sides). These signs are accompanied by long diamond-shaped lesions or areas of sunken and discoloured bark on twigs. These lesions eventually starve the leaves above of water and nutrients and causing whole branches to die.

Local spread (sometimes 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. The movement of logs or un-sawn wood from infected trees might also contribute, although this is considered to be a low risk.

What is being done about the disease?

Following the discovery of ash dieback in 2012, the government implemented a ban on the import of ash plants into the UK, as well as a ban on the movement of ash plants, seeds and trees into and around the UK. However, the ban doesn’t cover the movement of ash timber or firewood (except from sites where the disease has already been found).

Despite these efforts, the Woodland Trust says that the disease is still spreading and that landowners should ‘be prepared for a future without ash trees’ since many of the affected trees are in areas such as roadsides and hedgerows and by the time a diseased tree has been recognised, it is generally too late to save it.

In order to combat the disappearance of ash trees, the Woodland Trust is introducing a subsidised package for landowners which would see the planting of alternative native trees alongside the ash trees to replace them when they die.  The pilot planting scheme which distributes ‘disaster recovery packs’ of 45 native trees each, is being put in place in the areas deemed at greatest risk – Norfolk, Suffolk, Kent, East Sussex and Northumberland.

How do you recognise ash dieback disease?

Thankfully, early action from the Government has meant that the disease is far less widespread than it might have been.  It is still extremely important to recognise the signs of ash dieback to help prevent complete devastation of the ash population.

Ash dieback disease is a notifiable disease and if you think that you’ve spotted a case, then you need to report it to the Forestry Commission who have some great resources to help you identify whether or not local ash trees are affected:


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