Question
I live in North Eastern CT and I have a large Oak tree (about 24 inches in diameter) in the front yard. I have recently noticed a large crack in the bark. I went to get a closer look and found that the bark around the crack and found that the bark is rotting there. Is this a problem? Should I be concerned?

Answer
Sounds like a wound that fungi got into and is decaying the woody part of the tree. Decay fungi infect the wood and will not kill the tree. They might cause some structure weakness to the trunk. But this will take a very long time to effect a large tree. As long as the foliage is full and green there is nothing to worry about.
Sometimes an insect borer will enter the wound so I would recommend that you spray the wound area with an insecticide for borers--Merit is a good one to use. If the bark comes loose this loose bark can be cut off and this will help the tree heal over the wound.