Re: Iris Borers

In a message dated 98-01-31 12:57:17 EST, you write:

<< Claire -- Speaking from experience, I am sorry to tell you that the
 borer apparently is unaffected by Cygon once it is inside the plant.... This
is despite the fact that I soak the  plants, spraying from all angles, in an
effort to get complete
 coverage.  This apparently means either that (1) they were already
 inside the plant when I sprayed, or, (2) in some way, the soaking missed
 them, or (3) they hatched from eggs missed by the spraying.....At any rate,
these few borers have  fattened up on irises that have been soaked with the
systemic. >>

I am not clear about this business of "inside" the plant. Do we mean within
the fans, but still above the rhizome, or are we talking only about the larva
that has entered the rhizome? 

If I am following this correctly you are saying that the borer larvae which
are eating the plant from within are not inevitably affected by the systemic,
even when great care is taken to achieve complete coverage of plant surfaces--
which is supposed to render the plant tissues toxic-- and that  theyshouldt be
hit directly with the chemical to be eradicated. The suggestion, consistent
with what we have heard before, is that they may be affected more in the
leaves when young than when they reach the rhizome, albeit when they have been
eating the Cygon treated leaves and their Cygon-eating fellows, for some time.

Does this suggest that the systemic action is actually ineffective, that the
chemical must be working only as a contact poison, which it is not supposed to
do?  Or does it suggest the rhizome itself does not support the systemic? Or
that the plant absorbs only enough toxicity to kill young larvae? Or are they
maybe just being drowned in Cygon?

Anner Whitehead, Richmond, VA
Henry Hall, henryanner@aol.com
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