Re: Soft rot

Juri Pirogov wrote:
> 
> Mar 03/09/97 16:57, Griff Crump wrote:
> 
> > Juri -- . . .  Erwinia . . . What does
> > it do to your plants?
> >
> Griff,
> . . . soft rot . . . I'm very experienced in chirurgie, but not in prophylaxis! :-)
> I had a pure clay there, when began gardening 10 years ago.
> The clay was so dense, that spring water was forming a bog every year.
> Now, my soil is much more drainer, but clay is clay.
> Our summer is rather raining, and it is enough a week of rain to rot
> break out. So I cover my iris beds before planting by 2-3 inch of sand.
> It give good result, but not as long as like. Next year soft rot appear.
> 
> What preventive measures do you use?
> 
>

Juri -- I'm afraid that, like you, I'm more experienced in chirurgie
than in prophylaxis. The reason for this is that, luckily, I haven't
normally had many plants hit by soft rot/Erwinia, so haven't needed to
think about prevention against that particular malady. Last winter
(1995-6), however, was a disaster. I'm sure that Iris-L last year must
have been full of tales of woe. I lost about 80% of my newly planted
seedlings to the severe freezing and thawing, excessive rain and
ravaging winds. Most of the lost plants were thrown clear up out of the
ground, swamped in snow melt and then cooked by the sun. I lost entire
rows on the windward side of some beds. These had been big, healthy
plants, many looking like sows with piglets, going into the winter.
After cleaning up that sorry mess, I turned my attention to the
survivors. That's when I met Erwinia. On plant after plant, the bloom
stalk pulled right off, exposing the putrid yellowish rotted central
rhizome beneath. I spent days performing chirurgery, cutting out the
rotted central rhizome and hoping the surrounding increase would
survive. (I'm happy to report that most did.) I thought at first that
what I was dealing with was simply freeze damage, though I couldn't
understand why it attacked the central rhizome and bloomstalk almost
exclusively. After consulting the The World of Irises, I suspected it
might be Erwinia. Then, checking an older book, Molly Price's The Iris
Book, I found her description of Erwinia fitted the scenario in my
garden exactly. Neither book offers anything on long-term prevention,
but both -- Price, in particular -- offer valuable advice on control.
Both books seem to identify excessive moisture as the main culprit in
opening the plant to bacterial infection. Do you use raised beds? This
message is already too long, so, if you don't have either of these
books, let me know, and I will send you the pertinent text.

I dabble more than a bit in genealogy, Juri, hence am aware that several
of the early Crumps in this country were chirurgeons -- scalpel wielders
from way back.

Griff Crump, near Mount Vernon, VA  jgcrump@erols.com
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