Ash dieback is a non native fungal pathogen that was first identified in the UK in 2012, but had probably been in this country for several years prior to its first detection. It is a serious threat to native ash trees causing significant dying back of branches and mortality, particularly in younger ash.
Our ash trees have evolved and already live with a native fungus that causes dieback – Hymenoscyphus albidus. This fungus causes some dieback of branches but rarely kills the tree. However, the Hymenoscyphus fraxineus is a more aggressive fungus from Asia and has a much more devastating effect on our UK ash trees, killing many of them.
Evidence from the continent though suggests that about 1% of ash exhibit a high level of tolerance to this more potent version of the disease, and up to 10% of our ash trees have shown a good level of tolerance. This resistance is controlled by many genes and is heritable. By identifying those trees that have a high tolerance, we can breed from them to produce ash that are tolerant of the disease.
Ash Dieback
For information about the identification and symptoms of ash dieback, management options and financial assistance for woodlands, please visit Forest Research’s webpages which host lots of really useful information: https://www.forestresearch.gov.uk/tools-and-resources/pest-and-disease-resources/ash-dieback-hymenoscyphus-fraxineus/