I've been thinking about this too, what if you were to get an oak dowel, say 1", then cut some slots on the side on one end of it, then stir it around in the trub, and store it in the cellar, would the yeast be viable in a week? A month? etc. I've read that the picts beer was inoculated by their stirring spoon before they ever learned about yeast, but, was this spoon ever stored "dry" for any length of time? Numerous questions arise.