Acute Oak Decline is on the increase.
The disease causes the oak tree to bleed a black liquid and can kill it within five years.
To date there are 55 confirmed cases across southern and eastern England and the Midlands and experts say if we don't act now the consequences could be severe.
Peter Goodwin of Woodland Heritage says the disease "has the potential to change our landscape even more than Dutch Elm Disease".
Acute Oak Decline affects both the UK's native oaks - pendunculate and sessile. Forest owners and managers are worried that a lack of understanding of how the disease spreads means it will be hard to control.
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Acute Oak Decline - an overview