The first phase of the Living Ash Project ran from 2013 to 2018 and involved the screening and selection of common ash (Fraxinus excelsior) for resistance to Chalara fraxinea (as ash dieback was originally called). It was funded by Defra and delivered by a group of organisations with extensive experience with selecting and breeding ash for timber traits. It also used citizen science to look for trees in the wider environment. In total, 412 trees were selected from areas of high infection.
At the same time, Forest Research were screening 155,000 trees that were in production at the onset of ash dieback. They too selected those trees showing the most tolerance and 557 were grafted and planted along with the selected trees from the Living Ash project to form the National Archive of Tolerant Ash.