Ash dieback (Hymenoscyphus fraxineus)

What is Ash dieback?

Ash dieback, caused by the non-native fungus Hymenoscyphus fraxineus (formerly known as Chalara fraxinea), presents a significant threat to the UK's treescape on a scale not seen since Dutch Elm disease in the 1970s.

Ash is the third most common native tree in the UK, occurring in woodlands and other landscape settings, it has a high ecological value, cultural and historical significance within the county. Ash dieback is now found throughout the UK, eradication of the disease is not possible as this pathogen is an airborne fungus and is now considered endemic within the UK.

Information video on Ash dieback in Surrey's countryside

Latest updates

Notice of Ash dieback works on Surrey's Countryside Estate

Following a successful 2025 Ash dieback programme, works will continue in autumn and winter 2026. Works will be carried out at:

Brockham Hills – along sections of bridleways and footpaths along the North Downs Way. Please refer to the Brockham Hills map (PDF) for further information.
Chinthurst Hill – along the main path to the car park and leading up to the stone folly at the hilltop. Please refer to the Chinthurst Hill map (PDF) for further information.
Norbury Park - along sections of bridleways and footpaths near the railway line, Crabtree car park and the woodland hub. Please refer to the Norbury Park map (PDF) for further information.
Shere Woodlands - along sections of bridleways and footpaths along the North Downs Way, West Hanger car park, Combe Lane and Netley Plantation. Please refer to the Shere Woodlands map (PDF) for further information.

Works may take place in the areas indicated on the maps. Visitors may notice increased machinery and activity on site during this period.

We kindly ask everyone to take extra care and follow any on-site signage. If you have any further questions, please contact us.

To find out more, join us at our 'show and tell' session or at our informal 'drop in' session to learn about our plans and approach to ash dieback. Visit our what's on webpage for further information.

Updates will be posted on this webpage, through our Explore Surrey social media, on-site signage and our Countryside Matters newsletter.

How will Ash dieback be managed?

The Council (Surrey County Council) will focus on managing the risks posed from dying ash trees in high and medium risk locations and it will consider the nature conservation value that ash provides.

We manage this risk along Public Rights of Way (PRoW), our promoted trails, car parks and café/picnic areas, but in other areas trees are being allowed to fall naturally to benefit biodiversity. We advise visitors to be vigilant at all times at our sites to the risk of falling trees and follow any on-site signage.

The latest evidence suggests that at least 80% of the UK's ash will succumb to the disease, impacting both people and wildlife, presenting a significant risk management and economic challenge to our council budgets.

We recognise our duty to proactively manage the impact of Ash dieback on our own landholdings, as well as promoting good management across the wider county.

We will retain ash trees and monitor their disease progression where safe to do so, and in accordance with our tree risk management policy, only trees considered dead or significantly impaired or deemed a risk will be removed. Where possible timber will be chipped and processed, left at the site in the majority of cases.

We will carry out significant Ash dieback removal works outside of bird nesting season between September and March but will in necessary and specific circumstances, need to remove dead or high-risk trees in accordance with our tree risk management policy during this period, after careful risk assessment and ecological considerations.

We will take action to reduce the landscape and biodiversity impact via the following methods:

Ecological surveys will be undertaken where necessary to determine presence of protected species (for example birds or bats) and where necessary, replacement habitat or mitigation put in place.
Disease resistant trees will be identified, monitored and safeguarded where necessary.
Where appropriate, deadwood will be retained in the form of wood piles or standing habitats as ash trees die or are removed.
Allow for the natural regeneration of ash and for replacement tree cover, where appropriate, when the council will also consider planting native broadleaf tree species, particularly as part of a management plan or under Forestry Commission directive. These trees will be locally, or UK grown and sourced to ensure proper biosecurity (disease prevention). To find out about our target to plant 1.2 million new trees by 2030, see Surrey's new tree strategy.

Finally, the council will be clear in its communications to members of the public, elected councillors and partnership organisations as to why it's carrying out Ash dieback related work on its managed land. We will constantly review the guidance around this disease to ensure work is in accordance with best practice guidance and up to date, based on information from a variety of sources.