Re: CULT: HYB: 450 Known Rotters
- Subject: Re: CULT: HYB: 450 Known Rotters
- From: L* M*
- Date: Wed, 23 May 2001 08:29:19 -0400
Iris Moose (Bobby Baxter) in NC asked several questions after reading an article by Don & Ginny Spoon. He was referring to soft rot, not Botrytis rot, which is a
whole 'nother organism and affects a whole different bunch of cultivars.
> Why would anyone grow 450 clumps of iris that they know rot?
Because many people will buy them and are willing to do what it takes to treat and prevent rot in order to enjoy the blooms. Treating and preventing rot is not a
big deal in small plantings, and in locations where rot is not a common problem, not even worth mentioning.
> Are these iris being listed in catalogs? Are they being sold?
Yes, and yes.
> When they are sold are they identified to the buyer as rotters?
Probably not because even tho susceptibility to rot is probably genetic, the factors that contribute to an iris rotting are mostly under the control of the gardener
- except weather conditions.
I was amazed to see in either an article in the most recent Bulletin or Tall Talk (I can't remember where) the casual comment that most soft rot is caused by freeze
damage. Amazing because when I first joined this list and even in discussion of all the rot seen at the AIS Convention in Oklahoma, the presumption seemed to be
that all soft rot is caused by soil conditions (too wet, too rich). Of course, soil conditions (i.e., too much nitrogen or lush growing conditions such as warm
mid-winter rainy spells) contribute to sensitivity to freezes.
I disagree that most soft rot is caused by freeze damage. There seem to be two categories of soft rotters (presumably both types of susceptibility under genetic
control) - those prone to rot after freeze damage, and those prone to rot after heavy rains following drought during the time irises are actively growing. My
theory about this latter group is that the rapidly growing feeder roots occupy well aerated parts of the soil grabbing on to whatever bits of moisture they can
still find, then when it finally rains, those same last to dry pockets of moisture are the first to be without oxygen, and poof, suffocated roots, stressed plant,
hello Erwinea and friends.
> Are they being hybridized with? What are the consequences of using these
> rotters in hybridizing?
Yes they are. Some of them have bloom and plant characteristics that are highly desirable. Irises that don't like being drowned after drought in the spring/early
summer thrive in areas where it doesn't rain much at that time of year, which I think is probably most of the world where people garden. Similarly, ones that don't
like being frozen solid during active growth, thrive where they don't have to contend with that kind of weather. And harsh spring freezes are not something that
happens every year most places (my lucky garden being special). The central part of the US (east of the Rockies, west of the Appalachians) is especially prone to
this kind of weather, and folks east of the Appalachians got a nasty taste of it last year.
> What is the net effect of these rotters on all other aspects of iris related activity?
I'm not sure what you were asking here
> Is rot something that is simply accepted by growers and hybridizers as not being a real problem? Are growers expected to treat their gardens aggressively for
> rot?
Rot is acknowleged as being a real problem, but iris genetics is complicated (!), many of the traits being selected for are recessive and/or depend on the presence
of all kinds of modifier genes (in over my head here...), and we all want gorgeous blooms - so the flower comes first, then we select for the best growers with
those traits. Growers in difficult growing climates are expected to do everything they can to keep irises that were hybridized in less difficult climates alive. I
don't even try to grow irises that come from 'bloodlines' I don't know about.
> I advocate a tough position on the part of hybridizers to fight this rot,
> especially since the Spoons are convinced that "soft rot resistance is a
> genetic trait." ...[therefore] rot resistance can be bred for and should be.
How can a hybridizer growing irises in a place where the weather doesn't do bad things to their irises accomplish this? Mike Sutton and I tried to figure out a way
to freeze his seedlings during their most active growth phases by putting them in a deep freeze, but that would get the soil too cold. I'm not sure Mike was
entirely serious, but he does soak his with overhead watering to get rid of the 'rain after drought' sensitive ones.
> Are there hybridizers who have been identified with high a percentage of rotters in
> their hybridizing programs.
Don't we all wish it were that easy. Unfortunately, all hybridizers seem to have some lines that are more prone to rot in my location, but not others, & sometimes
an iris from a fairly rot free line will be unexpectedly susceptible & vice versa. Then there are those that rot some places & not others. Even in my horrid
growing conditions, CELEBRATION SONG never rots, grows like a weed, blooms heavily in spite of freezes that flatten other cultivars, yet it rots in other parts of
the country. Plus year to year variability & subtle shifts in general plant vigor makes some 'rot proof' cultivars suddenly rot.
I think one of the big problems with hybridizing for rot resistance is that in the parts of the United States where weather conditions 'encourage' rot, turnaround
time for producing new seedlings is soooo much longer than for areas with climate that doesn't encourage rot. Hybridizers working in good climates can get blooming
seedlings the year after seeds germinate, but it may take as much as 5 years in some locations. On top of that, in really stressed conditions, blooms are not
particularly fertile - either they don't produce pollen, or they refuse to set pods, or they can't carry pods to maturity. Layer on top of that, how few of those
seeds will germinate and go on to produce worthwhile offspring, and you have an almost unmanageable task if your goal is to have great bloom characteristics and rot
proof irises.
So, what happens is we fumble along with compromises - in the difficult growing areas, lots of pods in good bloom years and lots of seedlings from those pods that
flop in bad years. Judy Hunt suggested that it would be very helpful to hybridizers if local clubs in our region started pooling notes on what does well and
getting that information back to hybridizers. Some hybridizers probably don't care a whole lot about how their irises do outside their own growing climate (after
all, we are in this for the love of it mostly), but the bigger growers certainly do. They can't sell $50 irises to people if they won't grow.
Well, that's most of my soapbox comments. I will post a long 'survivor' report as soon as I finish getting all my lost labels re-done.
Linda Mann east Tennessee USA zone 7/8
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