Do you know the history of the stave? ie did you cut it from a live tree? How was it stored? This is important because sometimes its bluestain, which looks and smells bad but is only cosmetic. Happens when cut in summer, during high humidity. Other times the damage is structural, more likely if the tree was dead standing, or left out in the open after being felled.
At the least I would go down deep enough to not have any visible fungi showing.
