Question
I planted a tulip tree about 4 years ago in northern Illinois. Then it was about 1" to 1-1/2" diameter and it had a 1" cut in the bark at the ground level.  Now the cut has become an open scar with exposed dead wood that covers 1/3 of the trunk diameter and it is about 12" tall.  The exposed wood is dry & cracked.  The tree otherwise healthy and about 4" diameter at the ground.
What should I do about this scared area?

Answer
If the tree is growing and look healthy I would do nothing. Young trees will grow fast and the wound will heal over. If there is loose bark around the wound that can be cut off to help the healing process. do not use wound dressing on the area this will slow the healing.