TB, CULT, HYB: Rotters and Ramblings


On Wed, 16 May 2001 16:27:29 -0000 neilm@charter.net writes:
> Botrytis is STILL a problem in the mountain states.  I'd be 
> interested to know if certain lines are especially susceptible.  
> Char 
> Randall?  Care to comment?
> 
> Neil Mogensen
> 
Neil, Sorry to take so long to share my thoughts. Beware....this is long
and solely my unprofessional, unedited, rambling personal thoughts. We
are smack in the middle of gorgeous bloom right now and I spend all the
time I can outside! Hey, you can just stop and hit the delete key anytime
it gets toooo boring! 
        Waiting on more test results from the University people. It still
appears to be fungal probably botrytis of some kind. Pending those
results, will determine which chemical we need to use. At least it is
fungal and may be treated chemically rather than a bacterial erwinia soft
rot type which has no chemical cure, according to this pathologist. Very
very interesting, depressing, expensive, exhaustive, educational
experience with some of these newer babies! 

So far my observations in my own garden are that:

        The newer reblooming cvs are the most seriously at risk and least
disease resistant, certain hybridizers within that group are most
susceptible. But I water and amend them more too! I have kept records of
losses. As I recall the rust, red browns, burgandys do seem more tender.
Wonder how the plicata types like BLOW UP or EPICENTER will do in the
long run? BELVI QUEEN and BUCKWHEAT tend to start rotting if not lifted
and reset within 2-3 years. WAR SAILS and WINESAP are repeated rotters
for me, but so is BANANA CREAM and it isn't that color. HILO SHORES is
one of the worst and its a blue! 
        The stuff that I have soaked in bleach solutions have no more
resistance or vigor than those I didn't, possible less as I think the 10%
bleach solution tends to burn them somewhat....maybe it's our dry climate
adding to the slight burning I notice. I do feel this treatment is
possibly a good practice but not curative or even preventive for
botrytis. It is a surface disinfectant only.  
        While all material I've read says that the more crowded clumps
are more at risk, I've found that for me, it seems to be the longer the
clump is in the same spot, the greater the risk. But if you nick or
divide the rhizome its a goner if the rot is nearby. I certainly cannot
lift and clean and replant every single iris I have every single year,
nor would I want to. I wonder if the disease just continues to grow in an
area until it overwhelms the defense mechanism of the particular plant.
The resistance (along with other factors) of the variety must determine
why some cvs don't rot, some do. The newer beds of some of the older
cheaper varieties I ordered from 2 California growers and planted in 1999
are way more crowded than some of the others. I only lost 1 plant in
those beds. My older beds of newer varieties are spaced out much further
in between plants, have been in the ground a few years longer than the
1999 beds and they have been in terrible shape for the last 2 years now.
Yes, I know they should have been divided by now, but the first ones I
divided at 2 and 3 years on the clumps, died, melted, dissolved, departed
by the next year. Now the rot is fairly rampant in that area and I don't
think I need to worry about crowded plants! Both areas are new for iris
planting.
        Another factor is the natural aging and maturation process of the
clump. The mother rhizome is going to decay. The clumps that I got into a
few years ago and cleaned up and separated were the first to rot the
following year, I feel I probably spread it...but the *professionals*
that have been taking samples for us have cross contaminated plants and
beds far worse in a few visits than I have in several years! The
following year I was very careful to sterilize my shovel and utensils and
hands in between every plant. Slowed, but they still kept on dying.
Evidently, with this botrytis, it may or may not have made any
difference. The plant itself is infected and any cure has to be systemic,
not a surface treatment. 
        At least with this being a fungal problem, chemical treatment is
a possibility. With a bacterial disease like soft rot erwinia, I've been
told there is no chemical treatment possible.....which makes me wonder
about the triclosan and other treatments mentioned previously. Could it
be that they work as a preventative or containment measure although not
curative?
        I have used Cleary's 3336F for the past two years with limited
success. It does seem to slow down the spread of the rot for 10 days or 2
weeks. If there is any rain or I water, the stuff starts melting and
falling over again. One of the Dr.s I talked with did say that Cleary's
is one that is not effective for very long against the same disease. This
botrytis had already developed a resistance to it. Perhaps rebloomers and
their need for more water and fertilizer are just not a viable plant here
for me. The more vigorous and plentiful the Fall rebloom, the more likely
Spring death (not bloomout). I have lost oncers though too.
        Over the past 5 years or so I've also used Captan, Subdue, comet,
bleach, solarization, Dawn detergent, alfalfa pellets, sanitation and
some snake oils I've forgotten. The previous 25 years, a little water,
weeding and division when I had time was about it! The treatments and
chemicals pending now are very expensive, one of them is $349 per pound!
I could buy a lot of iris for that so I may not do anything! Except pull
out every sick looker, clean up my soil and replace with that vigorous,
unknown, old weedy type iris that grows for some other old lady around my
area!
        In my personal opinion, I've overdone the sanitation/treatment
and amendment part to the point of creating more problems for the general
health of my garden and soil not to mention entry wounds to the plant. I
now have some kind of nasty, invisible mutant fungus that I may or may
not be able to overcome.....I may just have to wait for nature to take
its course. Or the grim reaper to take his toll, I'm not sure which mood
I'm in! You can grow anything anywhere...but only for awhile. Also I've
learned, don't compare or try to grow these newer more tender tall
bearded iris with Grandma's hardy old flags! They just aren't the same.
Look at what does well locally, order proven varieties. If there is a
specific TDF cv you have to have, order more than one and from different
reliable sources. Multiple rhizomes from the same possibly infected
source are all going to be at risk. If a clump starts dying, dig it up
and isolate it. Then later, throw it away....I bet you won't "cure" it.
There are some slow starters though but they are just that, slow, they
don't appear to be rotting. Warmer weather, sunshine and drier soil have
been the best to slow this up for me. Last year I started potting all new
stuff in 3 gal. pots and I won't even plant it until I know it will live
through one year cycle. And I need to get healthier beds to plant in! Pot
culture has its own risks and requirements to deal with.
        Enough rambling, please keep in mind I am a hobby (but serious)
gardener, not a commercial grower or scientist and my impressions are
strictly a personal opinion. I hope someone, somewhere will find some
help from what I've shared. Tall bearded are my favorite flower and I
treasure the time I spend in the garden with them! The smells, the
colors, the vigor of the iris are all soooo wonderful. Enjoy this happy
plant!!

Char Randall
Melba, ID 83641
USDA Zone 6-ish
        
        

 

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