Signs of Ash Dieback: How to Spot It and What to Do

Written By Wez - 04/08/2026

What to look for, season by season

Summer (easiest time to spot): – Leaves wilting and turning black or dark brown, often hanging on the shoot – Shoots and young branches dying from the tip back – A crown that looks thin, ragged, and “moth-eaten” against the sky compared with neighbouring ash

Year round: – Diamond-shaped lesions: dark, sunken, elongated patches on the bark of stems and branches, typically centred where a side shoot joins, the disease’s signature – Epicormic growth: bushy clusters of new shoots erupting from the trunk and main limbs as the tree fights back – Dieback in the upper crown: bare, dead branch tips while lower growth persists

What it isn’t: a single dead branch, ivy cover, drought stress, or normal late leafing (ash is famously last into leaf) don’t equal dieback. The diamond lesions plus tip dieback together are the convincing combination.

How worried should you be?

Honestly: for the tree, quite. There’s no cure or treatment, and while a minority of ash show genetic tolerance and some mature trees decline slowly over many years, most infected trees deteriorate progressively. Young ash can die within a few seasons.

For you, the question isn’t really the disease, it’s what the tree could hit. Ash dieback does something arboriculturally nasty: it makes wood brittle. Infected ash become unpredictable to climb and prone to sudden branch and stem failure, which is why the disease has triggered safety-felling programmes along roads and railways nationwide. An infected ash in the back of a paddock can usually be monitored and left as long as possible (dead and dying ash is superb wildlife habitat). The same tree over your drive, your kids’ trampoline, or the public footpath is a developing liability.

What to do if you suspect ash dieback

1. Don’t panic-fell. Confirmed infection is not an automatic death warrant, and premature removal of a tolerant or slowly declining tree wastes a tree.

2. Get it assessed. A qualified arborist can confirm the diagnosis, judge the stage (crown loss is commonly scored in classes from slight to severe), and, crucially, assess what’s in the falling zone. Silver Tree Services assesses ash across Gloucestershire as part of free quotes for homeowners, and through formal tree surveys for landowners, estates, and anyone with ash along boundaries, roads, and rights of way, where the duty of care is real and documented inspection is your protection.

3. Act proportionally. – Early-stage, low-target tree: monitor, re-inspect annually – Declining tree near targets: staged reduction or removal while it’s still safe to climb – Severely infected tree: removal sooner rather than later, because past a certain point the brittleness means machine-assisted dismantling instead of climbing, and the price climbs with the risk.

4. Check the paperwork. Infected ash isn’t exempt from TPO consent or conservation-area notice unless it’s genuinely dead or immediately dangerous, and even then evidence and notification rules apply. We handle that as part of the job.

A Gloucestershire problem in particular

Ash is one of this county’s defining trees: hedgerow standards across the vale, hangers on the Cotswold scarp, and self-set ash in every neglected corner. That means most rural property owners here have infected trees whether they’ve noticed or not, and the sensible response is a walk-round, ideally with someone qualified, prioritising anything within falling distance of buildings, roads, drives, and footpaths.

The short version

Blackened summer shoots, diamond bark lesions, a thinning crown: that’s ash dieback. No cure exists, brittleness is the real danger, targets matter more than the diagnosis, and dying ash gets harder and dearer to remove the longer you wait.

Got an ash you’re not sure about? Send us a photo or book a look: free quotes across Gloucestershire on 01242 472560.

Related: Signs your tree is dangerous · Tree surveys · Tree surgery

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