Re: CULT: Leaf Removal & Soft Rot

This is interesting, but some factor must be missing,  either
in my data or in the university study.

The soil pH at my nursery is 5.0 down to 4.3 in spots.
Iris flourish there, as does Erwinia. Soft rot with that distinctive smell
at any rate. Is there another bacteria that causes soft rot that
makes that same smell? When I say flourish, I mean grow very well,
increase and bloom. Our pH measurements have been done twice
by sending samples to Ohio State University Ag Extension for analysis
as well as out own pH meter. Could the pH requirement you cite
be dependant on soil content and type?

Always wondering about stuff.

~~~~~~~~~~~~~~~~~~~~~~~~
John Bruce  jbruce1@cinci.rr.com
Hidden Acres Iris Gardens
http://home.cinci.rr.com/hiddenacres
SW Ohio,USDA Zone 5b
h*@cinci.rr.com
~~~~~~~~~~~~~~~~~~~~~~~~



> Following are some excerpts from an upcoming, not yet complete, Old South
> Iris Society news letter. If you (or others) will send me a mailing
address
> off list, I will be happy to forward a copy to you when the article is
> complete. Most of the info is gleened from source not specific to irises
but
> still applies to the iris world nemisis. I'll be out of town for the next
few
> days. I will elaborate further upon my return.
>
> Erwinia caratovora pH growth:
> The minimum pH in which the bacteria will grow is 5.6
> The optimum  pH level for the bacterias growth is 7.1
> and the maximum pH level in which the bacteria will grow is 9.3
> as per some university published data.
>
> Irises will survive, but not well, below the 5.6 pH range but reach their
> best growth rates above a pH level of 7 and above. Too, irises grow
> reasonably well in the 9.3 to 10.5 pH range. So one experiencing excessive
> rot problems might logically consider elevating (or lowering) the the pH
> level of their soil until they are satisfied with both the growth rate of
> their irises and the incidence of rot. Since other factors also influence
> erwinia c. growth as well as irises, we might reasonably expect to adjust
pH
> levels in our individual gardens to meet our specific conditions
(rainfall,
> etc.) in a way that minimizes soft rot incursions.  Apparently the growth
> rate of erwinia c. approximates the normal distribution curve slightly
skewed
> toward the lower pH ranges.
>
> Erwinia caratavora is non-spore forming. In laboratory conditions it will
not
> grow above 36 degrees C.( 96.8 degrees F). Sadly, it is not only active
but
> can grow and increase over a wide range of temperatures- from 3 to 35
degrees
> C. ( 37.4 to 95 degrees F). The bacteria is killed by extended exposure at
> about 50 degrees C. (122 degrees F). I have not yet determined the
> feasability/survivability of extended exposure of iris rhizomes to this
> temperature but do expect to do so when rot season arrives.
>
> I have an ailing friend and the only thing I dislike loosing more than
> flowers are friends. I will address moisture issues when I return in a few
> days.
>
> Smiles to all yawl,
> Bill Burleson 7a/b
> Old South Iris Society
>
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