That looks like just a knot hole to me, knot holes grow around the hole so no ring violation , un like a worm hole. I would just clean out all the dead stuff and maybe soak it in some thin super glue, be careful when you clean it out to try an not violate the rings [rings are usually thin around the hole] and it will probably be fine. I always leave some extra wood around the hole to make up for what is gone in the middle. ;)Good luck.
Pappy