Q.Plum tree disease
The leaves on my Victoria plum tree are shrivelled and obviously diseased and would like to know what is causing it. My Old English greengage is similarly affected with some leaves dead and brown. Most of the tree is affected. I got rid of a peach tree early this year which had peach leaf curl but I didn’t think this could affect plums. I hope the photos will help.

Certified GKH Gardening Expert
This may be Plum Pocket disease. Fungicides can help.
https://www.gardeningknowhow.com/edible/fruits/plum/plum-tree-diseases.htm