If it's the "spent" mother rhizome that is rotting, I think I'd remove the whole thing.....just save the increases, and pitch the rest. I can only assume it's the bacterial rot that you are talking about.........it has a VERY bad odor....and, if so, the bleach water will kill the bacteria. If it is one of the "fungal" type rots ........the odor is almost "sweet smelling, or slightly "yeasty" ( like bread dough) the bleach won't be nearly as effective.
