Re: Declining vigor/molliegrubs?
In a message dated 96-12-16 11:32:49 EST, you write:
Julie Allen asked
>But I wonder why some cultivars grow and
>bloom like gangbusters the first year after purchase, then seem to get a
>little weaker each year.
Last spring, we discussed this a little, and somebody said that they must
have the molliegrubs (iris humor). We were also calling it wasting disease
(iris tuberculosis!) (more iris humor). Somebody else (Chris Hollinshead?)
thought it might be scorch (not at all humorous). Very recently, someone
mentioned that cold adapted species sometimes are unable to stop cooking off
the energy they store during the day during our relatively warmer nights (I
think this was in reference to dwarfs), so they gradually lose all the
reserves they have and just dwindle away.
With absolutely no data to support my idea, I think it is a root problem -
next time I have a new variety with the mollies, I will look at it a little
more carefully - dig it up, poke at it some. Have you ever really studied
one of your 'shrinking' varieties?
As for delayed rot onset (DRO), I think rhizomes start out full of energy and
good health they bring from home, and are gradually subject to all the
stresses that are part of life away from iris heaven (too cold, too hot, too
dry, too wet, too rich, too poor, too many bugs and pathogens, all in rapid
succession) till they just can't take it anymore. Also, the more I hear
about stress induced rot, the more I wonder if it is a pathogen that doesn't
really get going until tissue is already dying (such as in frozen foliage,
wind damaged stalk bases, tissue suffocated underwater). I never treat for
rot - it is pretty self limiting in my garden - only rots out parts of a
reasonably vigorous clump. 'Course, these are the ones that lived through
those first few years.
Rick Tasco - Julie didn't include one important piece of information in her
post - she used to live and grow iris in iris heaven! Send flowers. : ).
LInda Mann firstname.lastname@example.org east Tennessee USA