Re: CULT: Leaf Removal & Soft Rot

In respect to the differences between field and lab conditions,
most home (inexpensive) pH meters are grossly inaccurate
and will vary quite a bit. Color test strips and chemical tests
will also vary widely because of  age of solutions, droplet sizes,
age of test strips, and human factors such as ability to match
color, contamination, etc.

> Its pretty common to find
> differences between laboratory data and the circumstances we actually
> encounter under field conditions. I usually chalk the differences up to
the
> uncontrolled variables encountered in the field.

I agree soil ph is not constant, but neither does it fluctuate widely
(especially in the short term) without human intervention. Assuming
no outside influences, soil is naturally buffered. I agree that most soil
will eventually return to its' native pH if left alone. Drastic change of pH
is not really all that easy, at least in the soil I have. I have amended
some
of the rows by adding lime--100# per 100'x5' row. After allowing some time
to pass for stabilization, measurement revealed the pH had changed by less
than a full point. Samplings that I have sent out for testing were taken
from a
depth of 4",  10 samples blended, with a  single sample for control showing
no significant difference. I should add that the ground in question was a
soy and corn field for probably 50 years, and fallow for three years prior
to testing. I would expect far different results from similar measurements
from around my home, where humans have been puttering in the garden,
adding this and that for 85 years. I would not be surprised by wide
variation
there, because I like my hydrangeas blue and my delphiniums alive.

> You probably already know that soil pH is a moving, ever changing target
and
> is finite only at a given point in time. <snip>
> Ultimately, native soil will revert back to it's original
> native pH level unless some action is taken. It is also reasonable to
expect
> rather wide variations in the pH levels of the individual samplings that
> constitute the final soil sample that one might collect for analysis.
> Measuring devices that indicate pH (meters and paper) do much here to
> alleviate persistent wonderin'.

I do not dispute the suggested optimal pH for bearded irises, just my
simple observation that they do just as well in my pH, found in a
heavy medium brown Ohio clay. I have noted that some irises
that do not grow well at my home in their pampered 6.8 pH soil
get moved to the acidic clay at the nursery and thrive, and some that resent
the
nursery love to come live with me.

I was originally taking to task the pH which bearded iris will thrive in
(the
study suggesting that they do not do well below 5.6 pH, and the fact that
erwinia won't survive below that same 5.6 pH. As you say, erwinia
is present in most soil. Maybe they dont like petri dish pH of 5.6?

Anyway, after rambling around a bit here, I think that soft rot will happen
just about anywhere if the plant is injured or stressed. Obviously a rhizome
that sustains injury such as chewing damage, root breakage from frost heave,
chemical burns, sudden frost damage, etc. is in a position for an
opputunnistic
attack from old Erwinia. A rhizome that is stressed because of constant
rain,
drought, and rollercoaster temps is in the same risk group.  I will agree
that
soil pH may play a factor, but have serious doubts that pH alteration alone
will drastically reduce incidence of rot across all soil types. And having
taken
trips to iris heaven (aka Oregon) I can assure you they have their share of
soft rot.

> Those missing factors? Maybe moisture levels, temperature and/or
ultraviolet
> light saturation?

Add plant stress and injury to the above. If we all continue wondrin' we may
eventually
get it figured out. In the meantime, where's my agristrep.......

John
~~~~~~~~~~~~~~~~~~~~~~~~
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
~~~~~~~~~~~~~~~~~~~~~~~~

---------------------------------------------------------------------
To sign-off this list, send email to majordomo@hort.net with the
message text UNSUBSCRIBE IRIS
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index