This is because a number of exotic tree pests and diseases have entered the UK in recent decades, such as the fungus Hymenoscyphus fraxineus which causes ash dieback and Phytophthora ramorum, the pathogen known to cause sudden oak death.
Forestry Commission England's Tree Health Team is constantly battling the spread and impact of tree pests and diseases. We joined the team for a packed out event recently in Liverpool (pictured) looking at the current state of tree health and pests and some of the action being taken to reduce threats to trees. You can view all the presentations from the day.
We need people to learn more about tree diseases and the signs and symptoms. You can read about the main tree diseases and pests on the Forestry Commission website.
If you see trees that you suspect are diseased, you can report it to the Forestry Commission's Tree Health Team using the Tree Alert service.
For general enquiries about tree health in relation to trees, woods and forests: