Jane - is the rhizome shriveling at all? I have had a few main rhizomes look a bit shrivelled. I have scraped any soft part off and poured a bleach/water solution over it. The increases kept growing and the mother rhizome never rotted out more. In the south we are so much warmer, so some of the big fat rhizomes from the pacific northwest react a bit to the change in moisture and warmth. Keep an eye on the rhizome, scrape and clean as necessary and try to let it dry out as much as possible.