I'd have to agree with Tom and others; just clean out the soft areas and use bleach water or bleach cleanser, then wait. Often the mother rhizome goes about its last stage of living after blooming and shooting off some increase. This treatment will not save the mama if in that stage but would save most or all of the increase.
Losing all the fan is often a form of rot which needs aggressive bleach cleaning and treatment of the area with bleach cleanser. This is usually caused by too much water around the roots. In my clay soil in areas where the soil is rather flat I often keep most of the rhizomes raised up in small hills to allow water to drain and not pool around them. Gentle lifting with a spading fork and filling under the clump has worked well to raise them where the soil needs no treatment. Arlyn has had this problem as well, especially starting in the spring with the snow melt causing puddling. I am on the watch for this again as the snow melts.
