A sh dieback (Hymenoscyphus fraxineus) has reached almost every corner of Staffordshire since it was first confirmed in the UK in 2012. If you own land with a mature ash on it, you have a legal duty of care under the Occupiers’ Liability Acts to keep it from injuring people or damaging property. This guide explains what the disease looks like, why infected trees turn dangerous quickly, and the point at which felling stops being avoidable.
What ash dieback actually is
Ash dieback is caused by Hymenoscyphus fraxineus, a fungal pathogen that almost certainly arrived in the UK on imported nursery stock. It was first confirmed here in 2012 and is now considered endemic. The disease targets Fraxinus excelsior — the common ash that lines so many Staffordshire lanes, hedgerows and back gardens.
The fungus reproduces by releasing huge numbers of wind-borne ascospores during the warmer months, usually from June through September. Spores land on ash leaves, the fungus moves down into the twig, then into larger branches, and eventually into the trunk. There is no cure. A small percentage of ash trees show genetic tolerance, but most infected trees decline progressively over five to ten years.
The Forestry Commission publishes detailed Plant Health guidance on the disease (originally listed under its older name, Chalara), and Defra’s Tree Health Resilience Strategy sets the national framework for managing it. For homeowners, the practical takeaway is simple: if you have an ash, assume it will be affected at some point, and learn what the warning signs look like.
Spotting it in your own ash
The clearest signs show up in late summer and autumn, when a healthy ash should be in full leaf. Look first at the crown. Infected trees show patchy, thin foliage, with bare twigs poking out at the canopy edges. Whole shoots die back from the tips inward, leaving blackened, withered leaves still clinging where they should have fallen cleanly.
On the trunk and larger branches, look for diamond-shaped lesions — dark, sunken patches of bark, often centred on a side branch. Fresh lesions ooze slightly; older ones crack open as the wood underneath dies. On younger trees, a single lesion can girdle the stem and kill the tree outright within a season.
In spring, infected trees come into leaf late, or unevenly — one half of the crown breaks bud while the other stays bare. Premature leaf drop in midsummer is another giveaway, especially when neighbouring ashes are still green.
None of these signs on their own confirm ash dieback. Drought stress, root damage and other pathogens can mimic them. But a tree with crown dieback, trunk lesions and patchy spring growth, all at once, is almost certainly infected and needs assessing.
Why it gets dangerous fast
"A tree with basal Armillaria can look reasonable from twenty feet away and yet be holding itself up on a sleeve of bark."
Ash dieback is not just a slow decline. The reason it has changed UK arboriculture so much is that infected ash becomes brittle in a way that other dying trees do not. The wood loses its flexibility long before the tree looks obviously dead, and limbs can shed without warning on a still day.
The bigger problem is what happens at the base. Once the tree is stressed, secondary fungi colonise the lower trunk and root collar. The two most common in Staffordshire are Inonotus hispidus (which fruits as a shaggy orange-brown bracket high on the stem) and Armillaria, or honey fungus (which sits at the base and spreads through the root plate). Both rot the structural wood. A tree with basal Armillaria can look reasonable from twenty feet away and yet be holding itself up on a sleeve of bark.
Three warning signs warrant urgent assessment, regardless of how much crown the tree still has: more than fifty per cent crown dieback, basal lesions or bracket fungi near ground level, and any visible cracking, weeping or movement in the lower stem. A tree showing any of those is in the territory where standard climbing dismantles become unsafe, and a contractor may need to rig from a MEWP or use a tracked harvester instead.
Your duty of care as a landowner
Under the Occupiers’ Liability Acts 1957 and 1984, anyone who owns or occupies land owes a duty of care to people who come onto it — invited or not. That extends to the public on adjoining roads and footpaths if your tree could reasonably fall onto them.
The test the courts apply is not whether you knew the tree was dangerous. It is whether you should have known. Case law has settled that for trees in a position where failure could injure someone, a reasonable owner arranges periodic inspections by someone competent. For a mature roadside ash, that typically means a written tree-condition survey every two to three years, more often if the tree is showing symptoms.
If the worst happens — a limb comes down on a car, a pedestrian, a neighbour’s conservatory — the question becomes: did the owner have a system in place that a competent person would consider reasonable? Photographs, dated inspection notes and quotes from arborists all help. A complete absence of any record is what tends to make insurers and courts uncomfortable.
When felling becomes the answer
Partial reductions do not reverse ash dieback. Cutting back the crown can reduce sail and buy time on a tree that’s otherwise structurally sound, but it does not remove the infection, and on a tree with basal decay it can actually make things worse — you’re sending a climber up something whose root plate is failing.
The usual threshold for felling is when one or more of these is true: the crown has lost more than half its leaf area, there is visible decay in the lower trunk, the tree is in a position where failure would cause injury or significant damage, or the cost of repeated inspections and reductions over the tree’s remaining lifespan exceeds the cost of replacing it.
A competent arborist will tell you plainly which category your ash sits in. If it’s an early-stage infection on a low-target tree (back of garden, no path or building within falling distance), monitoring is reasonable. If it’s a roadside boundary tree with basal lesions, the conversation is about how soon and how, not whether.
For protected trees — those with a Tree Preservation Order, or in a Conservation Area — you still need consent before felling, but ash dieback is a recognised ground for approval. Stoke-on-Trent City Council, Newcastle-under-Lyme Borough Council and Staffordshire Moorlands District Council all process these applications regularly.
Local context in Staffordshire
Ash dieback is widespread across North Staffordshire. The Churnet Valley woodlands east of Leek, the wooded fringes of Newcastle-under-Lyme, and the older garden suburbs of Stoke-on-Trent — Hartshill, Penkhull, Trentham, Wolstanton — all contain mature ash, much of it now symptomatic.
The pattern we see most often: a row of three or four boundary ashes planted in the 1960s along the edge of a back garden, two showing heavy crown dieback, one already shedding limbs in autumn winds. The neighbouring property has the same row on the other side of the fence, often with the same problem and no agreed plan between the two households.
This is where local knowledge matters. Contractors familiar with the area know which streets sit inside Conservation Areas, which trees carry TPOs (Trentham and Westlands have particular concentrations), and which sites can take a MEWP versus needing a full climbing dismantle. We match enquiries to a contractor who has worked on the specific kind of job your tree presents — not a general landscaper with a chainsaw.