Hymenoscyphus fraxineus — ash dieback — has now reached almost every county in England, and Berkshire and Surrey are no exception. If you have ash trees in your garden, on your boundary, or on land you manage, understanding what to look for and when to act could save you significant cost and prevent serious injury.
What is ash dieback?
Ash dieback is a fungal disease caused by the pathogen Hymenoscyphus fraxineus, originally from Asia. It arrived in the UK around 2012 and has spread rapidly. The disease attacks the vascular system of ash trees, causing progressive die-back from the crown downwards. There is no cure. Infected trees will eventually die, though the rate of decline varies enormously between individual trees — some fail within three to five years of infection, others linger in partial decline for a decade or more.
Signs to look for
The earliest signs of ash dieback are visible in late spring and summer: wilting or blackening of leaves and shoots, often starting at the tips of branches. The leaves curl, turn brown at the margins, and fail to drop cleanly in autumn. As the disease progresses, you will see die-back extending into the larger branches, with bark lesions and diamond-shaped lesions where dead wood meets living tissue at branch junctions. In later stages, epicormic shoots sprout from the lower trunk as the tree attempts to compensate for crown loss.
The danger: why infected ash trees are particularly hazardous
Ash is notoriously brittle, and an ash in decline from dieback becomes hazardous much faster than most other species in the same condition. The wood fails without warning — branches shed in calm conditions, and root systems can compromise faster than the visible die-back suggests. An ash tree adjacent to a building, road, or area of regular use that is showing signs of dieback should be assessed urgently, not monitored from a distance.
What should you do?
If you have ash trees and you have noticed any of the signs described above, get them assessed by a qualified arborist now. A tree that can be felled as a standing tree in a planned operation costs significantly less than one that needs to be dismantled piece by piece after it has become structurally compromised — or one that has already failed and caused damage. Early intervention is not just cheaper; it is safer for everyone around the tree.
We carry out ash dieback assessments across Berkshire and Surrey as part of our free site visit service. We assess the degree of infection, the structural risk, and the most cost-effective course of action — from monitoring and management to planned removal and replacement planting.