Re: CULT: pH, rot

Bill B was the source.  He has been sharing a lot of interesting
information, trying to understand what factors are involved in keeping
Erwinia happy/unhappy & this is one of many tidbits he's shared.

Anaerobic bacteria are present in all soils - there are always small
pockets of anaerobic conditions. Manure or any kind of organic matter
that can absorb and hold water to the exclusion of air will contain
anaerobic pockets.

The same is true for mineral soil. Clay particles are the smallest soil
particles, therefore the easiest to pack tightly so that oxygen has a
hard time diffusing into saturated soil.The entire iris bed doesn't have
to be underwater.

Iris roots will suffocate in anaerobic conditions, so roots rot and
Erwinia thrives.

From other information Bill has posted about Erwinia, once it gets a
toehold in a rhizome, it changes its behavior and becomes an infectious
agent rather than just hanging around.

I'm waiting for the posts from Bill about predators of Erwinia - slime
molds and nematodes are two I know about, but I know nothing about
encouraging them or whether or not they can really make much difference.

<Who said Erwinia is only able to grow under anaerobic conditions?  He
or she should see my iris bed where the best composted, best drained,
loose soil has the most rot.  Unfortunately, I believe the compost
contained some manure which I have found is the most certain way to get
the stinky rot. Francelle Edwards,  Glendale, AZ   Zone 9>

--
Linda Mann east Tennessee USA zone 7/8
Updates on migrant whooping cranes:
http://www.savingcranes.org/whatsnew/Class2002FloridaMain.asp
American Iris Society web site <http://www.irises.org>
iris-talk/Mallorn archives: <http://www.hort.net/lists/iris-talk/>
iris-photos/Mallorn archives: <http://www.hort.net/lists/iris-photos/>

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