What is killing my flowering tree, it can't be the Lichen? Can It?

I don't know.

No. Lichen are a sign of distress not a cause.

The lichen does not damage the tree. There can be several reasons a tree is dying.Has there been construction close by? People park heavy equupment under a tree or add a nice layer of dirt under the tree. Both will compress the soil and the roots will not get oxygen, so the tree dies. It looks like the tree is already too far gone... (My husband is an arborist)

Take a branch that has some of the damage on it from the tree to your local greenhouse, if you have one--they may be able to help. I use our county extension service which is associated with the state university. They diagnose issues for free on site, or for five dollars if they aren't there that day.

It definitely has a disease. What is the name of the tree?

Had a similar problem, it was a tiny pest within the wood. Cut all limbs off and I can see some new growth. However, my tree was not as large as yours. I also took mine to the local county extension service for diagnosis.

I have discovered the culprit. Root Rot

We had 34" of rain in the month of June and my setting on my sprinkler was set for everyday by company that un winterized it and they my sensor that turns the unit off if it rains stopped working. Once I realized this I shut it off.

The tree is a Robinia "Purple Robe" that needs well drained soil and need to dry out before rewatering. The Lichen was just a residual effect of all the moisture.

Now can I save this beautiful tree from the root rot? I read that I should give it food and treat for pest to give it a shot so it can close the rotted roots and start new ones??

Do we think this is necessary?