What it is
Ash dieback is a fungal disease (Hymenoscyphus fraxineus, formerly Chalara) that arrived in the UK around 2012 and has since spread through the national ash population. It is now the defining arboricultural issue in Leicestershire: ash was one of the commonest hedgerow, boundary and garden trees in the county, and the great majority of them will be infected over the coming years.
The fungus colonises leaves, grows into the twigs and then the larger wood, and progressively kills the crown from the tips back. A small proportion of trees show natural tolerance; most do not.
How to spot it
- Crown thinning and dead twigs at the outer edges in summer, when the tree should be in full leaf
- Leaves wilting and blackening without falling in early summer
- Diamond-shaped bark lesions where branches meet the trunk
- Dense tufts of epicormic growth (new shoots sprouting from the trunk) as the tree tries to replace the dying crown
- Small white fungal fruiting bodies on last year's fallen leaf stalks in late summer
Why it changes the safety maths
A normally decaying tree gives warning: fungi at the base, progressive lean, deadwood that drops over seasons. Infected ash does not follow those rules. The disease degrades the wood in a way that makes branches and stems brittle without obvious external signs, and they fail under loads a healthy tree would shrug off — including the load of a climber.
That last point has a direct cost implication. Once crown loss passes roughly half, climbing the tree is generally off the table, and removal means a mobile elevating work platform (MEWP) or remote dismantling — equipment and time that make the same tree substantially more expensive to take down than it was the year before. Acting early is not upselling; it is the cheaper option by a wide margin.
Your legal position
There is no legal duty to report or remove an infected tree in a private garden. But the ordinary duty of care still applies: if a tree you own injures someone or damages a neighbour's property, the question a court asks is whether you knew or ought to have known it was defective. Given how widely publicised ash dieback now is, "I had no idea" is a weaker position every year — and Leicestershire landowners with ash beside roads and public footpaths carry that duty to passing traffic as well.
What to do, in order
- Get infected ash inspected annuallyOnce a year, ideally in summer when the crown is readable. Annual inspection is both the safe and the legally defensible position.
- Prioritise by targetAsh within falling distance of a house, road, footpath or boundary comes first. Ash over open rough ground can often be left to decline naturally.
- Remove early while it is still climbableBelow roughly half crown loss, a sectional dismantle by a climber is usually possible — the cheapest, most controlled method.
- ReplantNot with ash. We can advise on replacement species suited to the spot and to Leicestershire soils.