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Ash dieback disease


Ash dieback disease has had a lot of media coverage recently, but what exactly is it, and what should we look out for?

Ash dieback is a disease of Ash trees caused by a fungus called Chalara Fraxinea. The disease causes leaf loss and crown dieback in affected trees and it may cause tree death.

Symptons to look out for

Symptoms of Chalara Fraxinea can be visible on leaves, shoots and branches of affected trees. In severe cases, the entire crown shows leaf loss and dieback and there may also be the formation of epicormic shoots on branches and the trunk.


Leaves can suffer from wilting and black-brownish discoloration at the leaf base and midrib. Dieback of shoots and twigs is also very characteristic.

Branches and stems

Small lens-shaped lesions or necrotic spots appear on the bark of stems and branches and enlarge to form perennial cankers. These cause wilting and dieback of shoots and branches, particularly in the upper crown.

Whole tree

Trees with withered tops and shoots are very characteristic. Heavily affected trees have extensive shoot, twig and branch dieback and often have prolific epicormic shoots.

For more information on Chalara Fraxinea please visit The Forestry Commision website.


Ash dieback disease