So I bought two plum trees that were grafted and a deer ate the bark off of one. my question is, is if I can cut the grafted/dead part off and graft a new plum scion onto it? do you think the rootstock is still alive? The deer ate the bark this winter.
It's a bit late for grafting, but you could try budding later when buds have developed on new growth. I would expect the rootstock to still be alive; if so, it should produce many suckers that could be used for grafting next spring.