Our trees and woodlands are under regular threat, especially from pests and diseases, many of which have come from abroad. While these often cause little trouble in their native habitats, some of these organisms can be virulent, fast-spreading and unstable in new environments where the natural controls that would minimise their spread in their native habitats are not present. The Authority works closely with the Forestry Commission with regard to tree health and diseases. We: Keep up to date on the latest threats to trees in the National Park.Report any sightings of pests and diseases to the Forestry Commission.Assist the Forestry Commission with any remedial work or restrictions as necessary. Who to contact Forestry Commission The Forestry Commission are ultimately responsible for advising, monitoring and taking action against tree pests and diseases. If you discover anything suspicious in the National Park you should report it to them. You may find the information on their website helpful. If you do identify anything that you would like to report, you can use this form or contact them using post, email or phone. Yorkshire Dales National Park Authority If you are unsure about a possible issue and would like reassurance before contacting the Forestry Commision, we can offer limited advice. It is most likely that we will refer you to the Forestry Commission. Please contact us to discuss further. Current threats Ash Dieback Ash dieback is a serious disease of ash trees which is caused by the Hymenoscyphus fraxineus fungus. The disease causes leaf loss and crown dieback in affected trees, and in most cases leads to tree death. Ash woodlands are a priority habitat in the Yorkshire Dales National Park and contain a number of tree species including ash, rowan, hazel, hawthorn and holly. We have been and will continue to monitor the progress of the disease and will endeavour to ensure that these habitats continue to be safeguarded. For more information please visit our page on Ash dieback Bleeding canker of Horse Chestnuts Bleeding canker is resulting in a significant loss of Horse Chestnuts across the National Park. Whilst it is not a native tree it nevertheless makes a significant contribution to landscape of the area. More information is available on the Forestry Commission website.