What is Chalara?
Chalara dieback of ash is a serious disease of ash trees caused by a fungus which was previously called
Chalara fraxinea, now known as
Hymenoscyphus fraxineus. The disease causes leaf loss and crown dieback in affected trees, and is usually fatal.
What does the Viewer show?
The Chalara Viewer opposite shows England, Scotland and Wales and a grid of 10km squares ('hectads'). The shaded squares show areas where Chalara dieback
has been confirmed to be affecting ash trees in the natural environment, and the colour of the square shows which year the first record in that
area was made. You can zoom in/out and find a UK address or postcode using the controls on the map.
Clicking on the map within a Grid Square will display information for that Grid Square in a pop-up window.
Where can I find out more?
For more information on Chalara dieback of ash please see the Chalara pages of the
Forestry Commission Website
How do I report Chalara?
We would encourage all members of the public to report the disease in new (unshaded) areas. If you suspect you have found a new
infection, please report it by using
Tree Alert on the Forestry Commission website.