Re: CULT: Leaf spot resistance

Here, leaf spot (the 'summer crud") resistance seems to be a gradient
from <vulnerable to the point of death without treatment> to <nearly
total resistance>.

All the cultivars I've found so far that fall into the near total
resistance category here are either Lloyd Zurbrigg or G.P. Brown
introductions.  These also tend to be some of the most tolerant of
erratic spring killing freezes (at least as far as foliage goes - some
with worse foliar damage may bloom more reliably).

However, there are many cultivars that are reasonably leaf spot
resistant.  Look for cultivars that have been hybridized (selected)
under your climate conditions.

Some of the best I've tried here so far include SUMMER OLYMPICS
(ancestor of I REPEAT, which I haven't tried yet), GRAND BAROQUE,
IMMORTALITY, VIOLET MIRACLE, HARVEST OF MEMORIES (extraordinarily
healthy), SUMMER GREENSHADOWS.  It's pouring down rain again, or I'd go
out and check for more.

The only two of these I've made many crosses with are IMMORTALITY and
HARVEST OF MEMORIES.  From the relatively small number of seedlings I've
raised from these so far, it looks like super disease resistance is,
unfortunately, <not> a dominant trait.

I'm happy to see this thread come up again.  I posted photos at the
beginning of crud season showing the range of foliar health here a while
ago, hoping to hear from others interested in hybridizing more disease
resistant cultivars, but didn't get much feedback.  The photos didn't
make it from Yahoo to the archives (posted three photos at once) - let
me know if anybody wants to see a 'resistant' vs 'vulnerable' plant for
this time of year.
--
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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