Ash dieback (Hymenoscyphus fraxineus) is a fungal disease that has spread across the country over the last decade and is now widespread throughout Leeds and the wider Yorkshire area. It’s expected to kill a large proportion of the UK’s ash trees. If you have an ash on your property, it’s worth knowing what to look for.
How to identify it
The signs are clearest in summer when the tree is in leaf:
- Wilting, blackened leaves that hang on rather than dropping cleanly.
- Dead branches and bare patches in the crown, often starting at the top and outer edges.
- Diamond-shaped lesions on the bark where branches meet the trunk.
- New growth lower down the trunk as the tree tries to compensate, a sign it’s under stress.
A single bad year doesn’t always mean dieback, but a steady decline across several seasons usually does.
Why it matters
The real danger with ash dieback isn’t the disease itself: it’s what it does to the wood. As the tree declines, the timber becomes brittle and unpredictable, losing the flexibility that a healthy ash has. Affected trees can drop limbs, or fail entirely, with little or no warning. That’s a serious concern for any ash near a road, footpath, building, garden or boundary.
It also makes the tree hazardous to work on. A diseased ash often can’t be safely climbed, so it has to be dismantled by other means, which is firmly a job for an experienced, insured arborist.
What to do
If you think you have an affected ash:
- Don’t panic, but don’t ignore it. Early-stage trees in low-risk spots can sometimes be monitored rather than removed.
- Get it assessed. Position matters as much as the disease stage: a tree over a lane is a very different risk to one in the middle of a field.
- Act before it becomes an emergency. A planned, controlled takedown is safer and cheaper than dealing with a tree that’s already failing.
We assess ash routinely across Leeds and out toward York, and we’ll always give you an honest view, including when a tree can sensibly be left alone. Book a free site visit and we’ll take a proper look.