Re: CULT: stress, pests and weather - very long

Hello, Donald, I have read with interest and sympathy all your messages about your iris disasters this year.  They make mine seem not too bad after all.  I heard on the news a couple of days ago that the grasshoppers are eating up all the corn in Nebraska and Oklahoma.  I guess the only thing you could do to save some of the irises would be to make screen frames to cover the beds.  I'm going to do something like that to a flower bed at the cabin to keep out predators, if it ever starts raining enough up there to keep anything alive.

I wonder why your Arilbreds go dormant in the summer.  Do you suppose it's the varieties?  I only have five, and mine never do.  I have neglected them this summer.  They get irrigation every two weeks, but the soaker hose I usually use for the alternate weeks broke, and I haven't replaced it.  They are very dry right now.  The spurias in that same row have gone semi-dormant, but the Arilbreds are green and healthy.

I agree that wet and dry does not seem to be the determining factor in rhizome rot.  The only thing that has a positive correlation with it is fertilizer.  The ones that I gave a little fertilizer (two teaspoons to a clump) in February have rot problems.  Those are the guest irises.  My irises didn't get any, and I don't see any rot in them.  One bed, right back of my lawn stands in water during irrigation, but I haven't had any rot in it.  I must remember:  A little triple supper phosphate is OK, but I must never put any nitrogen on my irises.

Dial soap seems to be working on the guests.  When I pull a loose leaf, it smells like soap not like rot.  I have three pots full of survivors by the windows in my family room.  Two of them have increases started.  In a few days I will put them out under a tree with a bird net over them to keep the scycle billed thrasher from digging them up.  There is one more clump I may have to dig to save.  I hope not, but if I must, I will.

Francelle Edwards  Glendale, AZ  Zone 9
  ----- Original Message ----- 
  From: Donald Eaves 
  To: iris-talk 
  Sent: Wednesday, August 07, 2002 5:45 PM
  Subject: [iris-talk] CULT: stress, pests and weather - very long


  Hello Folks,

  In response to my latest sad tale on attempting to successfully grow iris
  (or anything else), I received a post expressing sympathy and posing
  questions.  I thought I'd respond to the questions on the list.  I talk to
  myself a lot, but it is often instructive to try and frame a response to
  someone else's query.

  Summing up the situation here this summer to-date means the emphasis is
  still on grasshoppers.  They have eliminated the equivalent of 100% of any
  increase since spring.  Any increase escapees have been more than offset by
  whole mature and likely blooming size rhizomes also being consumed.
  Following the previous three years of drought with a couple of summers of
  long, dreadfully intense heat, this summer has been very nice.  Sufficient
  rain, lower temps and night temps actually cooling off rather than sitting
  in the mid 80s to low 90s for weeks on end.  The rain appears to have
  departed now and the day temps are back near the century mark - status quo
  for our dog days in these parts.  The weather should have made for a good
  year, but all the growth has been removed by the grasshoppers.  The tallest
  fans are shredded leaves barely over six inches - most are from four inches
  down to ground level and into the rhizomes.  This has resulted in SMALL
  rhizomes.  The few I've dug have not had the opportunity to grow larger.

  So, to the questions.

  >Are you loosing anything to rot that you have grown for a while
  >and never lost before?

  Yes.  It has to be qualified though since they were moved from the old clay
  beds to the new raised beds.

  >Are you loosing anything to rot at a dramatically different time of the
  year
  >than ever before?

  Maybe.  I'm currently seeing more rot this week at the same time than in the
  last several years.  I don't understand rot.  I have it when the weather is
  warm but not hot under rainy conditions.  But I have it much, much worse in
  totally dry conditions.  All the rain early in July and I had only one case
  of rot (all fans in the clump eventually got it and are gone, despite
  digging, drying and bleach treatment).  Currently the ground is very dry
  down to eight inches and I have more rot.  The plants need water, but what
  happens if they get it with the rot I'm seeing?  I'm afraid to give
  supplemental water under these conditions, but a summer shower may give the
  answer no matter.  I've no doubt it's Erwinia.  The smell, the look are
  there.  Yet it is occurring at the soil line where there is nothing but
  powder dry soil around the rhizomes.  I have almost zero success with bleach
  treatments and drying.  I've done both and had them continue to rot in dry
  shade up on a screen with good air circulation.

  >Have you attempted digging and storing any rhizomes as
  >opposed to leaving them in the ground?

  Not this year.  I've tried it in the past with mixed success.

  >I'm sure there are reasons other than
  >rot for some deaths, what is the appearance of the affected rhizomes?

  Sure is.  Some have been eaten until there were simply holes in the ground.
  Some have had the foliage eaten so short for so long they gave. Some in the
  same category have begun to bake alive in our intense sun.  With the fan
  left to shade them, or if they went dormant on their own, they might have
  escaped the cooking.  On one the appearance is a pitted and knawed rhizome.
  The other can be hard, withered and dry or very dry, but with an unnatural
  give when pressed.  Dead tissue either way.

  >The names of the survivors and the names of the deceased are important
  info.
  >of value.

  I'm not so sure.  While I respect and tend to agree with the observations
  that lead to the conclusion, I remain unconvinced of how strongly the
  genetics should be blamed here.  I would observe several things that have
  occurred this year and in the past on this piece of property.  The new
  raised beds - good soil, more moisture retentive, excellent drainage.  The
  iris grow better in them.  They also die better.  The very newest beds show
  the most rot.  The newest beds last year did the same, but haven't the rot
  this year.  Same plants essentially with a few new ones added, but no rot.
  New acquisitions have been hit the hardest.  Next are those that were moved
  (excluding seedlings).  Undisturbed clumps fare the best.  This has been a
  consistent pattern over several years here now.  Clumps that suffered rot
  several years ago and for several consecutive seasons, now seem to not fall
  prey to it.  In the same soil, same spot.  Some plants never quite recovered
  from the late bad freeze.  Not surprisingly, they have not withstood the
  damage handed out to them as well the others.  So the mortality rate is
  higher.  But planting timing comes into play here as well.  Those planted
  well past optimum planting time then failed to have lush growth when the
  freeze hit and did better.  Not something that can be predicted.  So the
  same cultivar planted on time in one place hasn't survived, but where it was
  planted too late has done pretty well.  Everything else is more or less
  equal.  So what would normally not be the best time to plant turned out
  better.  Result - some plants were simply luckier.  It was circumstantial,
  not genetic.  Here I can't make the genetic aspect hold up.  If I leave the
  plants alone and they survive two or three seasons, it stops.  Disturbing
  clumps and moving them around causes it to appear where it hasn't before.
  Unfortunately, iris clumps must be disturbed to continue to perform their
  best.  It just hasn't been the best thing the last few years here.  But then
  the clumps have dwindled as often as grown, so it hasn't been as necessary
  as in years past either.  The reasons for that aren't good either.

  >How are the arils and arilbreds doing?

  Depends.  I approach acquiring arils cautiously.  The success hasn't been
  good.  This year doesn't appear to be any better, or worse. I haven't the
  experience or numbers to even guess.  Arilbreds are also harder to evaluate.
  Under my conditions, nearly all tend to go dormant.  This year with cooler
  weather and more rainfall, some did not go dormant that usually do.  In the
  raised beds, almost none did.  In the latter case this has been to their
  detriment with the grasshoppers.  Without the pests, I think it might well
  have been to their benefit.  However, they are my principle interest, so
  they were planted on time.  They also tend to grow rapidly when they get
  enough warm days.  The result is that many were savaged by the late freeze.
  Mostly, they never fully recovered. There was some rot early, some were
  eliminated by grasshoppers because I exposed the rhizomes early in July
  after the more than seven inches of rain to avoid rot and instead provided a
  'hopper feast by doing so.  They're dead, but they didn't rot.  Now I'm
  seeing rot on some this week.  All these were either moved or new last fall.
  I also think a couple have cooked now, but won't know for sure 'til fall
  growing comes around.  The established clumps on those that didn't go
  dormant appear to be faring better.  On those that went dormant as usual, I
  won't know 'til they start growing - or not - in the fall.  I will be
  digging into a few soon, but haven't yet.  Those that didn't go dormant due
  to the weather, have been a favorite of the grasshoppers.  It's a rare
  arilbred with more than an inch of green showing.  All new growth has been
  kept pretty much mowed off.  Increases, and there were a lot on these types,
  are history.  I think their naturally smaller fans contribute to this as
  much as any other reason.

  As a last aside I will say I can't dig and leave exposed plants and rhizomes
  to dry until the grasshoppers are gone.  I dug some this week and tossed
  trash rhizomes down.  Today, those rhizomes are pitted and eaten.  Good
  'hopper bait if I could trap enough.  But it makes digging and reworking an
  existing bed difficult.

  Donald Eaves
  donald@eastland.net
  Texas Zone 7b, USA



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