This type of rot is apparently common on paeonioflius. I normally have rot on mine during their winter dormancy. I take a sharp knife and cut into the bulb until clear of the rot then coat the area with a dry antifungal such as rootone. Think of the tubers as potatoes. If you leave them alone for several months they'l rot too. Look in the aroid gallery under "amorph peony pic" and you see one of mine.

Thanks for your reply. I had been cutting large pieces out and coating it with sulpher dust. But the rot kept on coming back and have had to accept that the whole tuber is dead.
Where do you store yours when they are dormant? I had hoped that keeping them in a frost free greenhouse would have been ok. But as you say you might expect a potatoe to rot if left for months, so its not so surprising just disappointing. :(

cheers

bill

I looked at mine this weekend. I just stored in a cardboard box in my garage. 3 had no rot, 1, the largest, was about 20% rotted. In the past I have stored them in brown paper bags or buried in pure peat moss. Similar results with each method. I would expect best results being on a rack with good dry air circulation ~50 - 60F.