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Fwd: Re: HYB: freeze damage

Modern iris are a combination of various species and species clones.
Each from its own climate and well adapted to its own climate.  Clones
of same species can be addapted to its own climate in ways that make it
unsuitable to a different climate. For example, a black ash tree from
Norway, will go into winter dormancy in July  when planted in
Pennsylvania. That is when  it's potoperiod  trigger says winter is
comming. Daylight in July in Pen is the same as daylight length in
Norway in September.

With all these genes mixed up in iris,  you will have some with genes
for a colder climate and some with genes for a warmer climate, etc.

There also is microclimates in gardens, particularly if there are
differences in elevation, and or wind factors. When cold is near level
that can do damage, plants in a lower area can be damaged while plants
higher on slope will be fine. I saw this a couple of years ago with
someone in this area where some iris in  lower area of field were
damaged and those slightly higher were fine. Yesterday I was looking at
charts of fruit trees  with temperatures of  leaf damage and flower bud
damage  related to plant development and temperature. It varied between
fruit cultivars of same type and from type of  fruit to another. The
farther along foliage was developed, the less temperature drop was
needed to do damage.

Plants crowded together , as a mature clump, will likely survive the
same temperature  better then a single fan. Amount of weeds ( er
companion plants)  around a plant will also make a survival factor.

Chuck Chapman

Date: Mon, 17 Mar 2008 17:10:21 -0500
From: Linda Mann <lmann@lock-net.com>
Subject: [iris] Re: HYB: freeze damage

Among irises here, there seems to be quite a range in sensitivity to
sudden drops in temperature.  Remember those seedling photos I posted
last spring after the big freeze?  All were in active growth at the
we were hit with the freeze, but damage ranged from death to relatively
minor injury (they all looked pretty bad for awhile, but some were
killed outright).

Sudden freezes here can kill unprotected mature clumps as well as
seedlings but not do much damage to others that appear to be in the
active state of growth.

Maybe there are differences in growth activity that aren't apparent
by looking?

Most of this batch of seedlings that got frozen stiff were relatively
uninjured - a little freeze dried here and there.  But a few had their
tops killed.

<If temperature drop is sudden, then they can't do that, and if in
active growth can easily be damaged or killed.>
- --
Linda Mann east Tennessee USA zone 7/8
East Tennessee Iris Society <http://www.DiscoverET.org/etis>
Region 7, Kentucky-Tennessee <http://www.aisregion7.org>
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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