Q.Die Back on Fruit Trees
Hi I have a five year old plum tree which produced masses of fruit last year so much so that being inexperienced I did not support a couple of the more heavily laden branches and they snapped off. I had some die back during last year where the tips of newer growth would die back as well as aphid issues but nevertheless the tree still cropped magnificently. This year initially the tree made good growth even new shoots from the base of the snap off, but again the end leaves of the new young shoots curled and died followed by a slow progress of dying back along the wood. I have tried pruning out the dying ends but when any new growth appears it again dies back. The tree still has a crop but not as expected as many as last year. I would appreciate advice of treatment, cure or removal. Thank You. I have sparrow and tit boxes in use and they love the aphids so I don’t spray till the young have fledged.

I've listed several links for you to read and compare your tree issues with.
I would suggest you take leaf samples to your County Extension Office for a hands on diagnosis.
A soil test may also be a good idea, to rule out soil nutrient issues.
https://www.gardeningknowhow.com/edible/fruits/plum/plum-tree-dropping-leaves.htm
https://www.gardeningknowhow.com/edible/fruits/plum/plum-tree-diseases.htm
https://www.gardeningknowhow.com/edible/fruits/fegen/plum-pox-disease.htm
https://www.gardeningknowhow.com/edible/fruits/plum/common-plum-tree-pests.htm
https://www.gardeningknowhow.com/edible/fruits/plum/treating-plum-pocket-disease.htm
https://www.gardeningknowhow.com/edible/fruits/plum/plum-tree-fruit-spray.htm
https://www.gardeningknowhow.com/edible/fruits/plum/control-leaf-curl-plum-aphids.htm
https://www.gardeningknowhow.com/extension-search/