Why is my blooming plum tree not blooming like the one next to it?

Question

I have two blooming plum trees that were planted the same time ( 4/14). They were both doing good 15,16 , but mid way through the summer of 17 one of the trees started to lose it leaves. This spring one of the trees bloomed beautiful,where as the second one (the one that lost its leaves early) started blooming later with very thin leaf growth. They are about 30’ apart.

Answer 1

This can have many causes. Can you include a photo, so that I can see what is going on? This will help me to make a better judgment call.