Backwell Environment Trust

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Ash Dieback Disease

Unfortunately there are signs of this disease on some of our ash trees.

Ash dieback 1

‘Chalara’ or ash dieback disease, is a disease of ash trees caused by a fungus called Hymenoscyphus fraxineus. Chalara causes leaf loss, crown dieback and bark lesions in affected trees. Once a tree is infected, the disease is usually fatal, either directly or indirectly by weakening the tree to the point where it succumbs more readily to attacks by other pests or pathogens such as honey fungus.

Approximately 40% of the woodland on BET’s nature reserves is made up of ash trees so, if the disease did seriously take hold, there’s no doubt it would have a big impact on us. At the moment (May 2017), it seems to be the smaller ash trees (up to 4 metres tall) that are showing the most severe signs of infection, although a few 25 metres high mature trees have suspiciously still not come into leaf. We will probably not be required to take any drastic action such as felling a significant number of trees however, if any infected trees are located close to the road or footpaths, we would probably have to fell them on health & safety grounds.

Ash dieback 2

As the ash dieback fungus is classified as a quarantine organism, we have reported our sightings to the Forestry Commission. But it’s not all doom and gloom. It has been suggested that up to 3% of the UK’s ash trees could be resistant to the disease and as each ash tree produces thousands of seeds each year with a very high germination rate, the resistant strains could soon re-colonise our woodlands.

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