CULT: Iris Rot in Utah

Hi Donald!
       You write:
> > 
> You're saying MEMPHIS BLUES rotted in UTAH?  Did I miss something when I
> was through your state?  There was plenty of beautiful rock, but not much
> water.  How would MEMPHIS BLUES survive at all in other parts of the
land? 


Of course, there are not too many folks raising iris out in the Red Rock
country. I happen to live in the highest precipitation area in Utah
(outside the high mountains), where the average annual precipitation is
about 18". Most of this falls as snow between late October and March or as
rain or snow in April and May. Precipitation from June through September is
usually scant.

With this weather pattern we do experience some warm weather rot, mainly
bacterial soft rot, but it is not a major problem. Bearded iris do require
some irrigation in the summer, so the rhizomes are exposed to the moist and
warm conditions that favor this kind of rot at least periodically.

The *killer rot* here, however, is what is locally known as "winter rot",
which is Botrytis fungal rot. This strikes in the early spring at the time
of the big thaw (usually late March around here), when the winter
accumulation of snow melts rapidly while the ground is still frozen, so
that the melt water puddles at surface(=rhizome) level. With plenty of
moisture and temperatures between 30 and 40, botrytis has a heyday.
What makes it more insidious is that the rot gets going before all the snow
cover has disappeared, so often it is too late to do anything to save the
affected rhizomes once it is detected. This is the rot that twice did in
poor MEMPHIS BLUES for me.

Jeff Walters in northern Utah  (USDA Zone 4, Sunset Zone 2)
cwalters@digitalpla.net
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