i am still shooting one 20 years later that has lots of worm holes(its not like a crack),,, I really think yours will make a bow,,,
as suggested above you could sinew wrap that area,, I would probably do that if I was making the bow for someone,, if you use titebond and sinew it won't take too long,, filling with sawdust and glue is a great idea too,,,if you think it is a tomato stake send it to me and I will give it a try,,, if it turns out I will send it back