Botrytis

Question: Anybody had experience with botrytis and how do you/did you 
prevent/treat it? 
Botrytis is characterized by a fine grey black fungus that usually
appears on the iris rhizomes in very early spring, actively growing 
in the 30-40 degree F range. 
It can completely kill a rhizome if left unchecked.   
(please, feel free to correct this info if not 100% accurate)

I have had experience with this problem for a few years now. For me, it 
seems to be more prevelent in the "big" west coast rhizomes. I have tried 
the pre-plant dunk in the systemic fungicide Benomyl but the one time I 
did I left them in the 
bucket for about 30-40 min. and it proved to be too long as the plants 
were all very noticeablly stunted in their growth the next year. No botrytis 
though!! This year I'm just spraying the rhizomes and the close 
surrounding soil area with 
Benomyl when I notice the problem. Trouble is, sometimes by the time I 
notice it it is too late as the disease is well into the rhizome,probably 
from the cool autumn weather. Next year I'll try the dunk again, but 
only just a quick dunk in and out. I know that botrytis is soil borne and am 
wondering whether the fungus invades through the open division cut.  As 
the big rhizomes maybe "weep"  more, taking longer to heal the division 
cut, maybe they are  
more succeptible longer to this fungal invasion.  I am also going to try 
"painting" the division cut with bleach to help seal it up. 
Anyway, like to hear comments on all this. Looking to prevention more than 
treatment.

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Chris Hollinshead e-mail: bu336@torfree.net
Mississauga, Ontario Canada   zone 6b 
snow covered again...still...
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