Tulip (popular) tree needs help

[shydroanna]

I have a tulip (popular) tree that is about 20-30 years old. It has a black spot fungus, this was confirmed by an arborist several years ago. The arborist said that the tree still had good growth patterns that that the leaf spot, even though it was on every leaf of the tree, was not that serious. Fast forward a few years, I noticed that the bark on the bottom of the tree falls off with very little pressure. I did notice an occasional small white worm like bug but not too often. is this a new tree pest or disease or has the lear spot gotten worse? Is there anything I can do to save the tree?

 

[TreeWizard]

I'd keep it well watered and fertilized, and keep the weedwacker away from the tree. It looks to me like weedwacker damaged may have started the problem.