Is this Tree Sick or Dangerous?

[Ananisapta]

In the center of the picture below are two tall trees that formerly had identical foliage. Some years ago, lower branches were stripped. This spring, one of them looked very different from the other. They have continued up until now with this appearance of different foliage. I believe these are "Chestnut Oak" trees, as the locals call them. Certainly they drop a lot of acorns.

How likely do you think it that one of these trees is terminally ill? Should either or both be removed?

 

[old CB]

No tree in that photo looks ill, let alone terminally ill.