Re: Frost, twisted stalks.

Looks like classic yo-yo/rollercoaster late winter/early spring damage
to me.  Temperatures warm for a week or so, wonderful spring weather,
lush growth starts, followed by temperatures abruptly dropping to below
25oF.  Below 20oF, depending on stage of growth at the time, bloom
stalks are pretty well eliminated before they even start to form. Six to
8 weeks before bloom usually starts is when I see the most damage.  Some
cultivars are a lot more sensitive to this type of damage than others.

Are you also seeing some cultivars with the terminal fan killed (i.e.,
nothing there, or maybe a stunted, damaged fan)?

A good year to select seedlings that might do well here <g>

In years when this kind of damage is severe here, rot usually is also
severe, but often doesn't really get going until much later in the
season after it gets hot and humid, especially when accompanied by a few
thunderstorms dumping several inches of rain at a time.  Hopefully, your
climate is be cool and dry enough to escape that.

Other than generally not being good for the overall health of the plant,
it has no lasting effect once it recuperates.  My impression is that
most plants with this type of injury are more vulnerable to other woes
(leaf spot, soft rot, drought....).  Those that are rapid increasers
seem to recover a bit faster, but they are often also the ones most
susceptible to damage.

<Could this have been caused by the extreme cold last winter (-20 to
-25 F.)? Or something else?....Sharon Engstrom Colville, WA Zone 4b>

--
Linda Mann east Tennessee USA zone 7/8
East Tennessee Iris Society <http://www.korrnet.org/etis>
American Iris Society web site <http://www.irises.org>
talk archives: <http://www.hort.net/lists/iris-talk/>
photos archives: <http://www.hort.net/lists/iris-photos/>
online R&I <http://www.irisregister.com>





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