Damson Tree

All our damsons are self seeded in the hedgerows. There were 2 when we moved here that had very small fruit but they have both passed away. there are about 3 'new' ones appeared over the last 20 or so years that have much bigger fruit, halfway to the size of plums.
However, this year, I noticed some damsons with plum pocket disease so I don't know how long they will remain productive as I don't really have time to tackle it thoroughly.