Re: Bindweed, roundup, iris, rot

In a message dated 96-09-19 23:45:14 EDT, you write:

>Unfortunately, these old timers must be Mr.
>Only's because even though the TB's handled the round-up fairly well the
>SDB's in particular did not.  I am wondering if this is why I have the
sudden
>rise in rot. .....  I have one bed in a different area that I never
>got around to spraying and the iris in it are reproducing better, greener,
>just happier in general.  It is hard to know if I have a sudden case of rot
>(it is being reported all over town) or if the round-up caused the problem.

There was some discussion about Roundup being bad for iris and 'causing' rot
on the list quite a while ago (check the archives).  My experience is that
anything that does other than improve the growing conditions for iris causes
'damage' that sets up conditions for the rot organisms to get started.  So, I
suspect two things - 1) growing conditions were good for the bindweed, which
I assume means, worse than usual for the iris caregivers - too hot, too wet -
which means iris were not in optimal growing conditions before you sprayed
(and the SDBs may have been more unhappy than the TBs) and 2) the Roundup may
have caused some damage.   So you may have been in a catch 22 - not spray,
and get rot from less than optimal cultural conditions, or spray and get rot
from same, for other reasons.

I did a Roundup experiment about 10 years ago - took a clump of fescue that
was infested with a small rhizome of an iris from the last century (can't
find it's name -  sounds like geshundheit  - Rheingeplautz, or Rheinshnauzer
or... pale rosy lavender, the one Clarence says has great branching)).  I
sprayed that clump for about 2 years with heavy doses of Roundup and
eventually knocked back the fescue enough that the iris managed to bloom.  It
had these funny little pale lavender blooms, so I thought the Roundup had
damaged it pretty severely.   Turns out, it is a historic iris, and is
supposed to look like that.

HOWEVER, these fussy newer varieties probably can't take that kind of
exposure.  Also , we get a LOT of rain here, which probably minimizes
exposure of iris to the stuff.  Waxy leaves also probably help - there are
probably considerable mechanical differences in SDB  and TB foliage - maybe
differences in the cuticle?

Cure/prevention for rot around here is lots of roto-tilling - keep that air
around the roots.

Linda Mann lmann76543@aol.com east TN USA zone ?6-8?
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