I am trying to determine if I need to dig this tree out or give it time. From what I can find, I think it has verticillium wilt. The tree is a Basswood/Linden planted 3 years ago by the builder. Trunk looks normal and I do not see any bugs. Leaves did not have anything on them that I could see just turned yellow, brown and fell off. Started on one side and mostly gone in a week. The first picture was a week ago. Tree was full of green leaves. A couple days later is the picture with yellow leaves and a few days later the first picture. The twigs do not seem brittle or snap off so it is still alive. The bottom had a large circle of dirt with some mulch with an open area around the trunk. I have removed all the mulch now. I have irrigation that waters every other day. Please let me know your thoughts.