Plum tree problem

Question

What is the sticky substance on that plums that looks like dew dripping off

Answer 1

This is Honeydew, which is the residue from pests.
These links will help you.

https://www.gardeningknowhow.com/garden-how-to/info/what-is-honeydew.htm
https://www.gardeningknowhow.com/edible/fruits/plum/common-plum-tree-pests.htm