Tree with mutant plums

Hogroast2

I have a plum tree in the garden I can't identify with small (large olive-sized), very sour yellow plums growing on it.

The first few years I lived here it produced about a kilo of the plums.

For the last three years over half of the crop have been growing in all sorts of odd shapes, flat and banana-like, and they go leathery and inedible.

I've attached a photo to explain. Is there some way of stopping this from happening?

BobTheGardener

It's called 'pocket plum' - see here:
https://www.rhs.org.uk/advice/profile?PID=199

Dovefromabove

I think that looks like the early stages of Pocket Plum

https://www.rhs.org.uk/advice/profile?PID=199 

Hogroast2

Thank you so much, both, for the speedy and accurate diagnosis. I have confirmed that that's what it is. Taking off the diseased fruit will leave me with almost no tree at all. And I notice that there is no other way of dealing with it. Is it worth it to continue with this tree or should I think about planting something else?

Dovefromabove

If you're going to lose that much of the tree I think I'd call it a day with that one.  

Any ideas what you'd like to have instead?  

Hogroast2

I certainly do: a walnut or a greengage. If I dig out the plum tree, though, can I just plant another tree where the plum was and hope for the best, or ought the new one to go some distance from where the old tree was? That's a great shame about the plums, though.

Dovefromabove

I don't know, but I think I'd be hesitant to plant another prunus ... your tree must've been infected from somewhere so there may be Pocket Plum in the area.

I love walnuts