Traces of a fungus which is killing ash trees have been found in Berkshire.
Urgent surveys to find areas affected by Chalara, or ash dieback, are being carried out across Britain.
Cases have now been identified in at least 115 locations. The exact location of the Berkshire case has not yet been confirmed.
Chalara is being treated as a quarantine pest under national emergency measures.
Tree experts are asking people to keep an eye out for the disease, which causes leaf loss and crown dieback.
A video explaining the symptoms has been put together by the Food & Environment Research Agency (Fera).
Suspected cases should be reported to the Forestry Commission on 08459 335577 (open 8am - 6pm) or via firstname.lastname@example.org
Visit www.forestry.gov.uk/chalara for more details.
Watch the video from Fera explaining how to identify Chalara ash dieback below.
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