October 10, 2026
Ash is the tree you notice most after you learn to see it. Pale pinnate leaves, soot-black buds, grey ridged trunks that fork in neat opposite pairs. It lines lanes, holds up hedgerows and fills the wet corners of woods where little else will grow. Ash dieback has changed that. Across much of the UK the disease is now present, and where it has taken hold the practical questions are always the same: is this tree safe, what comes next, and how do I avoid making the situation worse?
Recognising ash dieback at each stage
Symptoms vary with the age of the tree, the site and the season, which is why a single glance is rarely enough. Early on, you may see dark blotches and wilting on leaves in midsummer, often on one side of the crown before the rest. Leaves can curl, brown and drop weeks early.
As the disease advances, watch for these signs:
- Blackened leaf stalks. The darkened rachis — the stem the leaflets sit on — often stays on the tree into winter. This is one of the most reliable clues.
- Shoot dieback. Tips and young branches die back, sometimes with lens-shaped lesions where the bark has sunk and darkened.
- Diamond-shaped bark lesions. Elongated dead patches on branches and, in badly affected trees, low on the trunk near the base.
- Thinning crowns. Dieback works from the outside in, leaving a sparse, twiggy look.
- Epicormic growth. Dense tufts of shoots bursting from the trunk and lower limbs as the tree tries to replace lost crown. On a mature ash, this is often a sign of serious trouble.
- Fruiting bodies. Small white discs on blackened leaf stalks lying on the ground in summer — the classic mosaic pattern.
Not every sick ash has dieback. Root damage, drought, squirrels stripping bark and other ailments can look similar. If the diagnosis matters — and near a road, it does — ask a second pair of eyes before you pick up a saw. Remember too that a small proportion of ash appear to tolerate the disease. Those trees are worth finding and protecting.
Confirming the tree is actually ash
It sounds obvious, but plenty of felling plans begin with the wrong tree marked. Check for opposite branching (buds and side shoots sitting in pairs, not alternating), pinnate leaves with roughly seven to thirteen leaflets, and velvety black buds in winter. Mature trees have grey bark with a diamond pattern of ridges. Younger ash often holds its leaves later than neighbours, which can confuse an autumn survey.
Assessing safety along paths and roads
Start with targets, not trees. Walk the site and ask where a falling limb or stem would land: a footpath, a bridleway, a road, a gate, a car park, a power line, a play area. A dying ash in the middle of a wet wood with no access is a habitat feature. The same tree leaning over a busy lane is a different problem entirely.
A workable approach for most woodland owners looks like this:
- Zone the site — high use, occasional use, no access.
- Survey each zone on foot, checking trunks at the base as well as crowns. Ash tends to become brittle before it looks dead, and failure can happen at the butt or mid-stem with little warning.
- Look for fungal brackets, hollowing, dead bark, deep cracks and soil heave at the root plate.
- Set survey intervals — annually at least for high-use areas, more often where decline is progressing quickly, and always after gales.
- Record everything: tree number, date, photographs, what you found, and the decision you made.
Anyone can do a basic walkover. Anything beyond that — deciding whether a tree over a road can stay — needs a competent, insured arboriculturist. Tree safety is a legal duty for landowners and occupiers, and the detail varies with the site, so take professional advice rather than relying on a general rule.
A tree that was fine last October can be unsafe by June. Decline in ash moves faster than most owners expect.
Planning the felling work
Resist the urge to clear everything at once. Retain tolerant ash, and keep low-risk trees and standing deadwood where they pose no threat — they support insects, fungi, bats and woodpeckers. Work in phases, taking the trees nearest targets first.
Timing matters. Felling in late autumn and winter avoids the main bird nesting season and reduces disturbance to bats, which do use ash for roosts. If trees may hold roosts, get advice from a licensed bat ecologist before work starts. Felling licences, Tree Preservation Orders and conservation area consent all have their own rules and exemptions, so check with the relevant forestry authority and your local planning authority before committing to a plan.
Ash is not a forgiving tree to fell. Brittle limbs, hollow butts and heavy side branches make it unpredictable, so use a trained team with the right kit, especially near roads where traffic management and highway authority permission may be required. Keep cut material on site where you can, and handle it according to current plant health guidance.
Replanting and shaping the next wood
Do not replant ash into the same spot. Disease pressure lingers in leaf litter, and a like-for-like replacement is likely to fail. Instead, build a mixed wood that can absorb future problems:
- Heavy clay soils: oak, hornbeam, field maple, small-leaved lime, wild cherry.
- Damp ground: alder, willow, aspen, downy birch.
- Thin or upland sites: rowan, birch, Scots pine, hazel.
- Understorey: hawthorn, blackthorn, guelder rose, dogwood.
Plant in intimate mixtures rather than large single-species blocks, so that if one species struggles, only part of the wood suffers. Encourage natural regeneration and thin it as it develops. Ash seedlings will keep appearing — leave any that look vigorous and healthy, as they may carry tolerance worth keeping in the gene pool.
Biosecurity in practice
Spores travel on leaves, mud and damp kit. Clean boots, tools and vehicle tyres before leaving a site, and knock off leaf litter as a matter of habit. Do not shift ash leaves, logs or saplings between sites without checking the rules. Prune ash outside the growing season where possible. Report suspect trees through the Forestry Commission's TreeAlert service, and buy planting stock from reputable UK nurseries that follow recognised plant health assurance schemes.
A checklist for the next site visit
Walk the site and mark the targets. Confirm which trees are ash. Check the base and the crown, not just the canopy. Record with dates and photographs. Bring in a professional for anything close to people, property or traffic. Prioritise and phase the work, and confirm consents before you start. Fell in the right season with an experienced team. Replant with a diverse mix and protect any tolerant ash. Clean your kit on the way out, then come back and look again — the picture will have changed.
Photo: NoblePrime / Pixabay
