the leaves on my plum tree are shriveling but the fruit is fine
The leaves are going black and shriveling up but the plums growing seem to be fine. I have just moved to this area and inherited the tree. The former owner says it happens all the time but the fruit is fine.
A bit hard to say. It could be sooty mold on the tree, which is mold growing on the honeydew excreted by scale or aphids. If you want to get the best crop from the tree, you should find out what the problem is and take care of it, because over time it is weakening the tree. If it is these insects, this article has some information: https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm
The best thing would be to take some leaf and branch samples to university or horticultural service for analysis. I'm guessing you're in the UK; this link will help you locate some help: http://mastergardeners.org.uk/get-involved/find-your-nearest-master-gardener/
If you're in one of the US Medways, try this link: https://www.gardeningknowhow.com/extension-search/