Ash dieback disease | Oxfordshire County Council

Ash dieback disease

A guide for planners, agents, contractors and members of the public about the ash tree disease.

Twigs affected by Ash dieback - Forestry Commission

Ash Dieback is a serious disease of ash trees caused by the fungus called Hymenoscyphus fraxineus. More about the disease - including a video showing how to spot the symptoms - can be found on the Forestry Commission website.

The disease has been confirmed in Oxfordshire, and some 400 young plants were destroyed on a private development site near Bicester. It is not yet clear if the disease had a chance to spread before the trees were removed and this will not be known until the summer of 2013.

What you can do

At the present time the disease only seems to be affecting young stock in Oxfordshire and as such we would urge members of the public to not undertake felling operations to any ash trees until they have spoken to us, FERA or the Forestry Commission.

We can all help to stop any potential spread of the disease by following the Forestry Commission’s simple biosecurity guidelines (pdf format, 2MB).

Following a statutory plant health order that came into force in October 2012 it is now an offence to move any ash plant material such as trees, whips, timber or logs generated from infected trees. It is also an offence to import any ash trees from outside of the UK.

How to report suspected cases

Hymenoscyphus fraxineus  is currently being treated as a quarantine pest under national emergency measures, and it is important that suspected cases of the disease are reported to the relevant public bodies. As more cases are discovered, a greater understanding of the spread and potential severity of the disease are evolving.

Please report any suspected cases of the disease directly by contacting:

Our role

Ultimately the direction that disease control will take will be guided by central government in the form of the Food and Environment Research Agency (FERA) and the Forestry Commission. We will have an important role to play locally, in disseminating information and where necessary, implementing disease control measures.

At this early stage of the disease outbreak it is important that we provide a measured and proportionate response to the existing situation. Whilst the experience in other parts of Europe such as Denmark is a salutatory one, government experts are still trying to understanding the situation in the UK and what, if any disease control or eradication measures (within the county) would be appropriate.


We have a dedicated Tree Team, a Natural Environment Team, and also support The Oxfordshire Woodland Project, who are available to offer advice to land owners or members of the public:

Rogue traders

Due to the presence of the disease within the county there will undoubtedly be some unscrupulous traders who say that trees have got the disease and yet they are perfectly OK.

Before agreeing to any ash trees being removed on your property we strongly recommend that you contact a professionally qualified (and insured) tree contractor. For a list of professionally approved contractors within your area please go to the Arboricultural Association website.

Our Trading Standards team also has a Buy with confidence scheme where you can find local tree contractors considered to be of an acceptable standard.

Reporting a rogue trader​

You can contact the Citizens Advice consumer service (Trading Standards) for consumer advice or to report a problem trader on 08454 04 05 06. Restricted movement of ash timber, products, plant material

Planning applications

Trees on County Council development sites are prioritised for retention in accordance with section 4.5 of BS5837:2012 Trees in relation to design, demolition and construction – Recommendations.

It is not considered appropriate by the council to downgrade a tree (for example, to move it from a B to C or U category) because of the potential risk of infection by C. fraxinea. It may be appropriate, depending upon the circumstances, to downgrade a tree that has a positive confirmation of the disease (by an appropriate public body).

Planning conditions

Following the Plant Health Order that came into force in October 2012 the movement of Ash planting stock has been banned. In light of this no ash species should be specified for planting in any scheme that is proposed for the county. Existing approved landscaping schemes that include Ash should be amended and an alternative species should be specified.

Applicants or their agents are advised to contact our Planning Team or the County Arboriculturist if they have any concerns.

Tree Preservation Order (TPO) and Conservation Area applications

As we do not deal with Tree Preservation Orders/Conservation Area notices, please contact your Local Planning Authority (district council).

Habitat and landscape value

The disease took two years to take hold in Denmark where it has affected 90% of the ash trees in the country.

Ash trees are an important feature of the Oxfordshire landscape within woodlands, hedgerows and parklands. Ash is a component of three of Oxfordshire’s Biodiversity Action Plan Habitats: Lowland Mixed Deciduous Woodland; Wood-Pasture and Parkland; and Hedgerows.

A native species to the British Isles, Ash is also important ecologically, supporting many different species of insects, birds, mosses and lichens. Mature and veteran ash trees can live up to 400 years and support many invertebrates, some very specialist or rare, such as the lesser stag beetle, the barred-toothed striped, the coronet, the brick, the centre-barred sallow and the privet hawkmoth. Hole nesting birds such as owls, woodpeckers and other birds such as the bullfinch eat ash seeds.

In the long-term Ash tree dieback may change the local landscape and ecology in areas where Ash is common.

Other pests and diseases on trees within Oxfordshire.

There are several other pest and diseases that are affecting Oxfordshire’s trees and woodlands and we would ask members of the public to be vigilant for the following:

At this early stage in the outbreak of the disease our position is to maintain a cautious approach.  As and when central government advice becomes clear, our position and advice may well change. As such this advice may be be subject to change at short notice.


Last reviewed
30 March 2016
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