Skip to main content

Ash Dieback

Ash dieback is a highly destructive disease caused by a fungus.

Published: March 17, 2023

Ash dieback is a highly destructive disease caused by a fungus. It is present in most parts of the UK and has the potential to cause significant damage to the ash tree population. Felling of affected trees is sometimes necessary, but current advice is not to cut down diseased trees as some may recover.

For further information on how to deal with ash dieback visit the Forestry Commission website. On the question of affected trees on privately owned land, the Forestry Commission advises: “You are not legally required to take any particular action if you own infected ash trees, unless your country forestry or plant health authority serves you with a Statutory Plant Health Notice (SPHN) requiring action.”

Apart from felling for public safety or timber production, it advises against felling living ash trees, whether infected or not, as there is good evidence that a small proportion will be able to tolerate the fungal infection.

However, it is important to keep an eye on the trees’ safety as the disease progresses, and prune or fell them if they or their branches threaten to cause injury or damage. In particular, watch for basal lesions (lesions, or cankers, forming near the bottom of the trunk), which can weaken the trunk and make the tree more prone to falling.

Among the first symptoms that an ash tree might be infected is blackening and wilting of leaves and shoots in mid- to late summer. Most infected leaves are shed prematurely by the tree, but in some cases the infection progresses from the leaves and into the twigs, branches and eventually the trunk, causing dark lesions, or cankers, to form in the bark.

Is this page useful?