Clear Bubbles on Plum Tree

Question

Leaves are starting to fall off and noticed clear, hard bubbles on the branches.

Answer 1

It may be peach borers. They produce a clear gum that could bubble on the branches. Peach borers do attack any stone fruit. Here is more information on them:
https://www.gardeningknowhow.com/edible/fruits/peach/peach-tree-borer.htm