So… yeah, the ash tree and mistletoe stuff? That’s actually based upon folklore. Both ash and mistletoe were used to repel werewolves, and both were used to cure werewolves as well. Ash trees in particular were used as wards against all sorts of evil. One story in particular mentions a man who climbed an ash tree to escape werewolves, and ash twigs were used to in ritual cures for lycanthropy. Even the juice of mountain ash berries were used in a fumigation that also cured lycanthropy. Likewise, while mistletoe repelled werewolves, the juice from the berries was one ingredient in curing werewolves.
You know the drill; head to your library and read these:
Werewolves: The Occult Truth -- Konstantinos
Werewolves (Around the world) --Elliot O’Donnell
Meet The Werewolf --Georgess McHargue, Stephen Gamell