Problems with plum trees

Question

Leaves are sticky with some sort of secretion. There appear to be small green aphids on the leaves. Fruit has brown marks and some is deformed.

Answer 1

This is called Honeydew and it is the secretion from pests.
Neem Oil is a good treatment.

https://www.gardeningknowhow.com/edible/fruits/plum/common-plum-tree-pests.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm