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Ash Dieback

Areas affected so far: The whole of the UK
Origin: Originally from Asia, arrived in the UK via mainland Europe
Ash Dieback

What is ash dieback?

Ash dieback (Hymenoscyphus fraxineus) is a fungus which originated in Asia. It doesn’t cause much damage to its native trees. However, its introduction to Europe about 30 years ago has devastated the European ash because our native ash species did not evolve with the fungus and this means it has no natural defence against it.

The disease affects ash trees by blocking the water transport systems. This leads to the dieback of the crown of the tree.

The disease is highly contagious and can spread quickly from tree to tree, causing widespread damage to ash populations. It is estimated that up to 95% of ash trees in the UK could be affected by the disease, which could have a significant impact on the country's ecology and biodiversity.

Ash Dieback

What does ash dieback look like?

  • Leaves develop dark patches in the summer.
  • Leaves wilt and discolour to black, possibly shedding early.
  • Dieback of the shoots and leaves is visible.
  • Dark brown, diamond shaped lesions develop where branches meet the trunk.
  • The inner bark of the tree looks brownish-grey under the lesions.
  • Epicormic growth from previously dormant buds further down the trunk. This is a common response to stress in trees.
Ash Dieback

What happens to the tree?

Unfortunately, as the disease takes hold of the tree, the wood becomes increasingly brittle with branches breaking away from the main body of the tree. If they are not dealt with, trees are at risk of collapsing, presenting an immediate danger to the surrounding area.

Ash Dieback

Exert from the government website:

Tree safety

People who manage ash near roads, railways, buildings and other publicly accessible land must consider the risks posed by infected ash. Trees or woodlands in these areas should be risk-assessed, monitored and managed to reduce the risk. By law, the owner of land where a tree stands is responsible for the health and safety of those who could be affected by that tree. If you are unsure about health and safety risks, consult a fully insured tree management professional who holds a relevant qualification.

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Removing the tree

Once the tree has been diagnosed with ash dieback, there is no chance of recovery. As the disease takes hold and the wood becomes increasingly brittle, it also becomes more dangerous for our staff to take down. If you are concerned that your trees are suffering from ash die back, please get in touch and we will arrange a site visit where Tom can identify whether the disease is present and can advise you on the safest course of action.


We advise that the trees are replaced with native or near native trees, Tom can advise you which species would be most suitable depending on location and environmental factors.