At 05:53 PM 98-02-27 -0700, you wrote:
>In doing some spring cleanup, I noticed something I hadn't before
>dealt with on many of my TBs in one bed. Several clumps had
>one or two little fans with what looked like black dust on the rhizome
>and in many cases going up to virtually cover the few inches of
>newly growing fan. These fans were brittle and broke off easily.
>The closest diagnosis I could find in The World of Irises is botrytis,
>and it wasn't very encouraging about it. It looks as if the problem
>of finding space may be somewhat reduced this year here.
>All alternate diagnoses or coping advice would be appreciated.
I think the very best thing you can do is to solarize that soil this summer.
We had that problem a number of years ago and solarizing cleaned it right out.
Vernon BC Zone 5