Ash dieback – Chalara fraxinea

posted on October 10, 2012

UPDATE: ash dieback was confirmed today to be present in two woodlands in the East of England. These are the first confirmed cases of the fungal pathogen outside tree nurseries. 25th October 2012.

A devastating new disease affecting ash trees is now present in Britain.

Chalara fraxinea webpage

Chalara fraxinea information on the Forestry Commission website

A fungus called Chalara fraxinea (C. fraxinea) causes leaf loss and crown dieback in affected trees, and it can lead to tree death. It has devastated 90% of ash trees in Denmark, leading to concerns that the disease could have a similar impact on the British landscape as Dutch elm disease. It is likely that Defra will implement an import ban by November after calls from across the forestry sector.

Ash trees suffering from symptoms likely to be caused by C. fraxinea have  been found widely across Europe over the last 10 years. These have included forest trees, trees in urban areas such as parks and gardens, and also young trees in nurseries. Symptoms include the wilting of leaves and dieback. During the dormant winter period it can be hard to spot but black lessions on stems are tell-tale warning signs.

It was first reported in the UK in February 2012 after it was found in a consignment of infected trees sent from a nursery in the Netherlands. Over the Summer new cases were soon reported first in central England and soon after the north and east. It has been found also in four recently planted sites in Scotland.

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. Visit the Forestry Commission webpage to find out more.

Read more about our work to combat tree pests and diseases at

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  1. […] comes the same month as the devastating new disease on ash, Chalara fraxinea or ash dieback, finally attracted the national media attention it deserved, and the same year that sweet chestnut […]

    Pingback by SYLVA • reviving Britain's wood culture — April 17, 2013 @ 4:32 pm

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