We use some essential cookies to make this website work.
We’d like to set additional cookies to understand how you use forestresearch.gov.uk, remember your settings and improve our services.
Preparing to search
The tiny white Hymenoscyphus fraxineus fruiting bodies on the rachises (stalks) of the previous year's fallen leaves from an infected ash tree. These mushroom-like fruiting bodies develop and burst open in summer, releasing thousands of spores into the air. The spores can be blown by the wind on to the leaves and bark of healthy ash trees, infecting them with chalara ash dieback.
Blackened buds and wilting leaves of an ash tree in the early stages of chalara ash dieback infection.
Chalara ash dieback lesion associated with leaf scar.
Mature ash trees in Denmark with chalara ash dieback
Brown staining of ash caused by chalara ash dieback.
Another view of wood staining caused by chalara ash dieback.
Unless otherwise stated, pictures belong to Forest Research or the Forestry Commission and are Crown copyright.
Cookies are files saved on your phone, tablet or computer when you visit a website.
We use 3 types of cookie. You can choose which cookies you're happy for us to use.
These essential cookies do things like remember your progress through a form. They always need to be on.
We use Google Analytics to measure how you use the website so we can improve it based on user needs. Google Analytics sets cookies that store anonymised information about: how you got to the site the pages you visit on forestresearch.gov.uk and how long you spend on each page what you click on while you're visiting the site
Some forestresearch.gov.uk pages may contain content from other sites, like YouTube or Flickr, which may set their own cookies. These sites are sometimes called ‘third party’ services. This tells us how many people are seeing the content and whether it’s useful.