Ash dieback and the duty on landowners

The ash dieback landowner duty is not a special statutory obligation. It is the ordinary duty of care you already owe to anyone who might be hurt by a tree on your land, applied to a species that is dying across the country and that fails in an unusually dangerous way. What changes with ash dieback is the inspection interval and the urgency, not the legal test.

Ash affected by the disease goes brittle. That is the point that matters for everything below.

How the disease progresses

Ash dieback is caused by the fungus Hymenoscyphus fraxineus. Spores from leaf litter infect the leaves in summer, the infection moves into the twigs and branches, and the crown thins from the outside in. Blackened wilting leaves in late summer, diamond-shaped lesions where a side branch meets the stem, and a flush of epicormic shoots on the trunk as the tree tries to compensate are the signs to look for.

Crown decline is the visible part and it is not the dangerous part. The risk comes from basal lesions at the collar, which open the tree to honey fungus and other root decay, and from the way infected ash loses the fibrous, flexible failure behaviour that healthy ash has. A declining ash can shed large limbs without warning, in still weather, and a tree with a compromised base can go over entirely.

That is why arborists treat a heavily affected ash near a road or a footpath differently from an equally affected ash in the middle of a field. The hazard is the same. The target is not.

The duty and what reasonable inspection means

Liability comes from negligence and from the Occupiers' Liability Acts. The courts have never required a landowner to know what an arboriculturist would know, but they do expect a system of inspection that is proportionate to the risk, carried out by someone competent to spot obvious defects, and acted on.

In practice that means zoning your land. Trees within falling distance of a highway, a public right of way, a building, a car park, a campsite or a neighbouring garden get frequent and recorded inspection. Trees in a woodland interior with no access get very little, and the law does not ask for more.

Two statutory levers sit alongside the common law. The highway authority can serve notice requiring an owner to deal with a tree that is dead, diseased, damaged or insecurely rooted and likely to fall onto a highway. And a council can act under nuisance powers where a tree threatens a neighbouring property.

An illustrative example: a farm with 40 roadside ash along a lane, 30 in a shelterbelt behind a barn and around 200 in a wood with no public access. A proportionate regime inspects the roadside trees annually from the ground by someone trained to recognise decline, inspects the shelterbelt every few years, and leaves the wood alone unless access changes.

Records that actually help

Keep the inspection record simple and keep it. Date, inspector, method, each tree or group with a reference, the condition observed, the action decided and the date the action was done. A photograph of each roadside tree taken at the same point each year shows crown decline better than any written description.

The record is what demonstrates a reasonable system if something does fail. An undocumented inspection that happened is worth less than a documented one that happened, and both are worth more than a policy of felling everything.

Felling diseased ash

A felling licence from the Forestry Commission is normally required to fell growing trees above the volume thresholds in the Forestry Act 1967. Several exemptions matter for ash. Trees that are dead are exempt. So is felling that is immediately necessary to prevent danger or to abate a nuisance. Trees in a garden, an orchard, a churchyard or a public open space are exempt, as are stems below the diameter thresholds set out in the Act.

The danger exemption is narrower than people assume. It covers what is immediately necessary, so it will not stretch to clearing a whole block of moderately affected ash in one operation because you expect them to become dangerous in three years. Where that is the plan, apply for a felling licence, and consider a woodland management plan instead, which can cover phased removal and replanting together.

Retain what you can. A small proportion of ash shows tolerance to the disease, and the current advice from the Forestry Commission is to leave healthy-looking ash standing where it is safe to do so, because those trees carry the genetic resistance the species will need.

Where tree preservation orders still apply

A tree preservation order or a conservation area does not disappear because a tree is ill. The Town and Country Planning (Tree Preservation) (England) Regulations 2012 exempt works to a dead tree and works that are urgently necessary to remove an immediate risk of serious harm, but the exemptions come with procedure.

For a dead tree you must give the local planning authority at least five working days' notice before the work, unless the situation is an emergency, in which case notice goes in as soon as practicable afterwards. Photographs taken before the work, and ideally an arboricultural report, are what you will rely on if the council questions whether the tree was dead or dangerous. Removing a protected tree on an unevidenced assumption of dieback is how owners end up prosecuted, and the penalties for damaging a protected tree are not trivial.

There is also a duty to replace a protected tree that is removed under an exemption, in the same place and as soon as reasonably practicable, unless the authority dispenses with it. Where the work falls short of removal, specifying the crown works precisely in the application is what gets a consent issued rather than queried.

Biosecurity when moving material

Ash dieback spreads mainly by airborne spores, so the fungus does not need your boots to travel across a county. Biosecurity still matters at the site scale and for the other pests moving through the same supply chains, including the emerald ash borer risk that sits behind the restrictions on ash imports and movement.

Clean soil and leaf litter off boots, tools and tyres before leaving an infected site. Fell and chip on site where you can rather than carting brash around. Check the current plant health position with the Forestry Commission before moving ash material off the holding, because notices change.

Replanting and the planning dimension

Do not replace ash with ash. The point of a replanting scheme after dieback is species diversity, so that the next pathogen does not take the whole shelterbelt. Match the replacement to the soil and the exposure, mix at least three or four species, and plant at a density you can maintain.

Planning control returns as soon as development is involved. On a site coming forward for an application, an arboricultural survey to BS 5837:2012 will grade ash with advanced dieback as category U, unsuitable for retention, and the question then becomes what replaces it in the tree survey and the landscape strategy. Removing declining ash immediately before an application is submitted invites the suspicion that the clearance was about the scheme rather than about safety, so record the arboricultural reasoning at the time.

Bats and nesting birds are protected regardless of tree health. Check before felling between March and August, and check any tree with cavities, lifted bark or woodpecker holes at any time of year.

This is general guidance, not legal advice. Tree safety duties and felling exemptions turn on the facts of each tree, so take arboricultural advice and check the position with your local planning authority before acting.

Draft the arboricultural supporting documents for a site in minutes and send them for professional review at PlanScope.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.