Re: CULT: ROT: Is it genetic?
- Subject: Re: CULT: ROT: Is it genetic?
- From: Linda Mann l*@volfirst.net
- Date: Fri, 09 Aug 2002 09:30:03 -0400
I agree with Donald's assessment of the role of genetics and assessing
how big a factor it is in occurrence of rot (and other diseases &
deformities (i.e., stunted stalks)). A big, difficult tangle to sort
out, and different answers with different stressors in different
regions, years, and gardening practices..
To elaborate on the role of selection by the hybridizer - I think of
three factors that come into play, none of which is intended as any
criticism whatsoever and it certainly isn't my wish that ANY of these
factors change or we'd lose some of the best new patterns and colors.
One is that the primary goal of the hybridizer may be to select
cultivars that will thrive and be gorgeous in a particular market. For
example, in some offlist discussion with Barry Blyth last year, he
commented that their primary market is Australian growers. Therefore,
most of their hybridizing efforts go towards early bloomers that will
bloom before it gets too hot (remember Sharon McAllister's recent post
about crosses failing at temps above 85oF). And early bloomers are most
likely to be the ones that start growing too early here, suffer a lot of
late freeze damage, hence rot. So if I buy a Blyth cultivar (which I
do, because they are different and have patterns that I love), I know it
may be a high risk & I don't know enough about most of the genetic
makeup to make an informed choice (anybody know of an inexpensive source
of historic Blyth irises?). Some do very well for me.
Another is that the hybridizer may be growing & selecting seedlings in a
climate that simply doesn't stress the plants enough to be able to tell
how vulnerable they are to various stressors. Summer dry climates don't
expose the seedlings to high humidity and alternating drought and
deluge; cold summer climates don't expose seedlings to summer heat and
humidity. Usually, these are also high risk - this is where I look at
pedigrees to see if there is potential. Again, some irises from these
hybridizers do very well here. And some even fight weeds (I'll post
some photos eventually).
The third is where the hybridizer is working to achieve a new pattern or
color. Most catalogs acknowledge that these 'firsts' aren't always the
best performers. I usually avoid these, waiting for later generations
with improved toughness or recommendations from others.
Donald in wretched (a lot more wretched than mine!) TX growing
conditions said:
<..If, e.g., some combination of genes makes an iris susceptible to rot
in wet conditions in heavy clay soil, suppose that same combination
makes it resistant in a sandy situation. Partial dominance of genes and
how they act when combined prevent ruling such scenarios out
altogether. When you mix in the myriad factors that influence how an
iris may or may not grow in conditions and how that genetic interplay
may help or hinder its growth, then it would seem unlikely that
selecting by the hybridizer is going to have a lot of impact.
Currently I just think the genetic disposition will not prove a feasible
method of curbing or eliminating rot....or some other maladies. I do
think it is likely a factor, but I don't think it simple enough to draw
any broad conclusions from. Perhaps my conditions are too variable for
me to draw a bead on it.>
--
Linda Mann east Tennessee USA zone 7/8
American Iris Society web site <http://www.irises.org>
iris-talk/Mallorn archives: <http://www.hort.net/lists/iris-talk/>
iris-photos/Mallorn archives: <http://www.hort.net/lists/iris-photos/>
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