> Dennis -- This sounds like Erwinia. Often as a result of freezing, but
> not necessarily, the central rhizome, particularly, is hit by a
> bacterial infection. Cut out the infected part, roots and all, as best
> you can. Then spray the exposed cut rhizomes that remain with a 20% or
> stronger bleach solution and don't put dirt back on top of the cut
> surface. Let the sun and air in. This may cost you this year's bloom,
> but it will usually save your plant. Good luck.
Griff and Dennis,
This almost certainly is Erwinia. This is an "opportunistic" pathogen
that attacks plants when they are in a weakened state. Borer damaged
plants often get infected with Erwinia, as are those that have been
severely damaged by freezing. In the areas of Cincinnati, Lexington, and
Louisville, a rather unusual thing can happen. This is to have large ice
shard to form in the soil when a rapid freeze sets in after a major
rainfall event. In Lexington, I saw some rhizomes that had been pierced by
said ice shards. This damage could allow a pathogen, such as Erwinia, easy
entry into the rhizome.
Griff's control advice is excellent. It will work.
Mark A. Cook