Can ash dieback be treated?

There is no treatment available to a homeowner, and pruning does not cure it. A small proportion of ash shows natural tolerance, which is why an assessment rather than automatic felling is the right first step.

Does every infected ash have to come down?

No. Trees with limited dieback away from buildings and paths are often monitored, and some recover partially. Removal is driven by how much of the crown has gone, whether the base is decaying, and what the tree could hit.

Do I need permission to fell a diseased ash?

In a garden you usually do not need a felling licence, but a tree preservation order or conservation area still applies. Dead or dangerous trees are treated as exceptions, with notice given to the local planning authority.

Why should an affected ash not be climbed?

Because infected ash wood becomes brittle and can fail without warning, including branches a climber would normally rely on. That is why safe working method is part of the assessment, not an afterthought.

High risk

Updated 30 August 2026

Ash Tree Dying Back

An ash has thinning, patchy foliage, dead twigs across the crown and clumps of new growth low on the trunk.

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What's happening?

Ash dieback is a fungal disease that has spread across the UK ash population, and a garden ash showing crown dieback is the most likely explanation for the pattern above. It kills from the outside of the crown inwards: leaves wilt and blacken, shoots die back from the tips, and the tree responds by throwing out bushy epicormic growth on the trunk and main limbs. The reason it matters more than most tree diseases is what it does to the wood. Infected ash becomes brittle and unpredictable, often losing branches without warning, and the loss of root anchorage that follows can bring a tree down with little notice. That also changes how the tree can safely be worked on: climbing a badly affected ash is not appropriate.

What usually causes it?

Infection by the ash dieback fungus, which arrives on airborne spores rather than through contact
Repeated seasonal infection building up over years, so the crown thins progressively
Secondary decay fungi colonising a weakened tree, particularly at the base and roots
Drought or waterlogging stress accelerating decline in a tree already infected
Honey fungus taking hold in the roots of a weakened ash
Ash bark beetles and other secondary pests attacking a declining tree
Older or already stressed trees declining faster than young vigorous ones

Is it dangerous?

Yes, and specifically because of how the wood fails. Diseased ash goes brittle, so branches snap and fall without the flexing and creaking that usually gives some warning, and advanced cases can lose root anchorage and go over in moderate wind. Keep the area beneath a badly affected ash clear, and treat it as urgent if it overhangs a road, a footway, a building, a garden used by children or a neighbour's property. This is also a real risk to whoever works on it, which is why an affected ash is often dismantled from a platform or felled from the ground rather than climbed.

Can I fix it myself?

Look properly and record what you see. Photograph the whole crown from the same position each year — the honest measure is what proportion of the canopy is dead — and look for blackened leaf stalks, dead shoot tips, diamond-shaped lesions on young bark and bushy regrowth on the trunk. Check the base for signs of decay or honey fungus, because that is what usually decides the timing. There is no treatment you can apply, and pruning does not cure it. Keep the area under the tree clear, and do not climb it or work on it from a ladder. Report tree pests and diseases through Forest Research's Tree Alert if you want the sighting recorded.

When should you call a tree surgeon?

Call a tree surgeon for an assessment as soon as the crown is visibly thinning, and promptly if the tree is near a building, boundary, road or footway, or if there is decay at the base. Earlier is easier and safer than later: a tree with some sound wood left can be worked on and reduced, while a brittle one becomes a bigger and more difficult operation. Ask specifically about how they intend to work on an ash, because a badly affected tree should not be climbed.

What will the tree surgeon actually do?

Confirm ash dieback and estimate how much of the crown has been lost, rather than treating any dieback as terminal
Check the base and roots for secondary decay and honey fungus, which usually drive the decision
Assess the targets under and around the tree and set the urgency from that, not from the diagnosis alone
Recommend monitoring, a crown reduction, or removal, with a defined re-inspection where the tree is retained
Plan the method around brittle wood — a platform or a ground fell rather than a climb where the tree is unsafe to work
Fell or dismantle, grind the stump, and advise on replanting with a different species

Frequently asked questions

We’re happy to answer all your questions.

Sources & References

Fungus Growing On The TrunkHigh risk Cracked Branch Hanging In The TreeEmergency Tree Has A Preservation OrderLow risk

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