Ash dieback (Chalara fraxinea)

Photo copyright Stephen Trotter (WWT) 2012Ash trees in Warwickshire

Ash Dieback (Chalara fraxinea) of ash is a serious disease of ash trees caused by a fungus called Chalara fraxinea (C. fraxinea), including its sexual stage, Hymenoscyphus pseudoalbidus (H. pseudoalbidus). The disease causes leaf loss and crown dieback in affected trees, and usually leads to tree death.

Ash trees suffering with C. fraxinea have been found across Europe. It was first reported in Poland in 1992.

In February 2012, the disease was found in a consignment of infected trees sent from a nursery in the Netherlands to a nursery in Buckinghamshire, England.

C. fraxinea is being treated as a quarantine pest under national emergency measures, and it is important that suspected cases of the disease are reported to the forestry commission.

A pictorial guide to recognising the main symptoms of the disease has been produced by the Forestry Commission.

The Forestry Commission's exotic pest alert provides more information about the disease.

Additional Information and Latest Updates

  • A new strategy to tackle Ash dieback has been published today alongside the Tree and Plant Health Task Force’s interim report. Environment Secretary Owen Paterson announced on 6 December 2012. 

    The Chalara Control Plan sets out the Government’s objectives for tackling the disease and outlines what further action we will take over the next few months.

    The Government has already introduced a number of control measures to reduce the speed of spread, which are in line with these objectives. A ban on import of ash trees and movement of trees around the country will remain in place. Landowners and conservation organisations will continue to work with Government agencies to check sites across the UK for signs of infected trees.

  • Oliver Rackham has produced an interesting document concerning Ash Dieback and other diseases effecting our trees.

Reporting suspected cases

If you think you have spotted the disease, please check the symptoms first by following the guidelines on the Forestry Commission web site, before reporting it to one of the following:

Further information
For the latest information and updates, visit the forestry commission Ash dieback web page