Ash trees are wonderfully proud, with vast woody structure and exotic looking leaves. Ash Dieback (hymenoscyphus fraxineus) is a disease from Asia which has spread through Europe and into the UK, and in time it is expected to kill the majority of our Ash trees. It is affecting us greatly in Pembrokeshire as Ash trees are one of our most common trees.
The loss of so many mature trees from one species will threaten the wildlife that rely on them. So it is vitally important that we do not cut down all Ash trees just because they are showing some signs of the disease. Nationally we expect a small percentage to be disease resistant and survive.
Trees with Ash Dieback die from the top down, i.e. twigs and branches decaying and snapping off over the years. In severe cases, and after many years, the dying trees can get basal decay, become unstable, and blow over.
Because of this, dying trees only need to be worked on if there is a high risk target below, for example roads, footpaths or property. In some cases only certain branches posing a risk need be removed. In cases of badly infected trees, it maybe necessary to fell the whole tree if there are targets within falling distance.
If there are no high risk targets beneath the tree, a mature dying tree provides benefits for many years, such as habitat for nesting birds, feeding grounds for wildlife, linking insects and fungi to surrounding trees, and providing structure and shade on the landscape.
Before doing any work it is important to assess if, and how badly, a tree is infected by the disease, what action should be taken (if any), and if anything needs to be done immediately.
Now more than ever it is important to plant trees to replace the loss of Ash trees.