Ash dieback disease in trees

Information about ash dieback disease in trees.

What is 'ash dieback'?

Ash dieback is a fungal disease that affects ash trees. Its scientific name is Hymenoscyphus fraxineus but it was previously called Chalara fraxinea and the term Chalara is still used to distinguish it from other tree diseases. It has spread throughout much of Western Europe.

The disease causes die back of the tree's crown and infects the vascular system causing blockages. It is spread by wind-blown fungal spores which are released from the fruiting bodies on dead twigs and leaves in summer. The disease causes leaves to wilt and also characteristic lesions of dead tissue in the bark.

Ash dieback appears to kill saplings and young trees very quickly, often within one year. Infected older and larger trees can take many years to die.

It should be noted that there are many other tree diseases, a number of which infect ash, which can be confused with ash dieback. Expertise are therefore required to correctly identify the disease (please see the questions below).

What is an ash tree?

The information on the Forestry England website should be able to help you to identify an ash tree:

Forestry England - ash tree species (external website)

Is ash dieback in the East Riding?

Yes. The Forestry Commission has confirmed that ash dieback is present at numerous sites across the East Riding.

What should I look out for?

The Forestry Commission has produced the following guide on what to look for when identifying the disease:

Forestry Commission symptoms guide ash dieback (pdf 282kb)

Details are also available at the Forestry Commission website:

Forestry Commission - ash dieback (external website)

Who do I report sightings to?

To help the Forestry Commission and the Government to understand the scale of this disease across the UK and to mitigate the spread of the disease, please report sightings to the Forestry Commission:

Ash dieback helpline: 08459 33 55 77 (open 8am - 6pm every day)

Ash dieback email address:

If the tree is on or next to the highway, or if you think the tree is on land owned by the council, then please fill out the following form:

Report a diseased tree sighting on council land (council website)

What is the council doing about ash dieback?

We are monitoring local ash trees, such as those on the public highway and in open spaces, and also those on our Local Nature Reserves, such as Millington Wood, Humber Bridge Country Park, Danes Dyke and South Landing.

We are following Government guidance and working with partners, including the Forestry Commission.

It is important to remember that we are not responsible for ash trees in private ownership. If you suspect an ash tree on private land has the disease, then please report this via the Forestry Commission helpline (08459 33 55 77).

If you suspect an ash tree has the disease and is on council land, then please fill out the e-form above. This will help us to identify and manage infected trees on our estates.

If you are the owner of a tree that is protected by a tree preservation order or with a conservation area, please follow the advice on the Forestry Commission website:

Forestry Commission - ash dieback (external website)

What if the ash tree is protected by a Tree Preservation Order?

If you own an ash tree protected by a Tree Preservation Order or within a Conservation Area, please follow the above links for advice on how to identify whether your tree is infected.

Current Government advice is that mature trees will not be removed. Where infection is found in mature trees, the scientific advice is to leave them where they are as infection does not spread directly between trees, but only via the leaf litter.

If you are the owner of a protected tree which you suspect has died as a result of infection then please email for guidance on how to proceed.

Can I still go for a walk in woodlands?

You can still enjoy a walk in woodlands in the East Riding, provided you have the legal right to do so. This may be because the woods are open for public access, such as Woodland Trust sites, are nature reserves or larger Forestry Commission sites, such as Allerthorpe, or are served by existing public rights of way.

The countryside is still open for people to visit and the chance of the disease being spread by visitors to the countryside is accepted to be low. However it is recommended that you do not pick leaves and move them from one site to another.

Where can I find further information about ash dieback?

For further information please visit the following website:

Forestry Commission - ash dieback (external website)

More specific advice for landowners can be found on the following website:

National Farmers' Union - ash dieback (external website)

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