Q: My 23-year-old Dogwood tree is having an issue on the trunk. Other than this, it looks fine. I saw some ants going in a hole on the trunk.
A: I finally got my crystal ball Time Machine out of the shop, so let???s try it out on your photo.
What I see is that several years ago someone cut a limb off the trunk but left a stub sticking out a couple of inches. The tree was never able to heal over the stub. It finally rotted away and left a hole in the trunk. The hole allowed rot to descend down the trunk to the ground.
So now you have a dogwood with a weakened trunk.
At this point, there is nothing you can do except keep the tree as healthy as possible. One thing dogwoods love is to have mulch under the tree all the way out to the branch tips, which keeps the roots cool.