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Re: Iris Borers

  • To: Multiple recipients of list <iris-l@rt66.com>
  • Subject: Re: Iris Borers
  • From: Dorothy Fingerhood <daf10@cornell.edu>
  • Date: Sun, 1 Feb 1998 13:20:43 -0700 (MST)

At 10:55 AM 1/31/98 -0700, you wrote:
>Claire -- Speaking from experience, I am sorry to tell you that the
>borer apparently is unaffected by Cygon once it is inside the plant. I
>find that Cygon spraying in the early spring is very effective, but
>there are always a few borers that survive (i.e., fewer than a dozen
>among hundreds of clumps). 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. I would hate
>to think that there is more than one hatching cycle and that the moth
>can deposit eggs after the spring spraying which then hatch that same
>growing season.

Griff and all--I believe this IS the case.  (More than 1 hatching per
season, that is.)  WOI recommends spraying beginning when the foliage is 6"
high, then at weekly intervals until the end of June!  Here, we have
usually had good control with 2 sprayings, but recently a commercial grower
in the area found reports of up to 3 separate hatches in this climate, and
attributed some of the damage they suffered to this "third hatch," which
was unwelcome news for all of us.

Dorothy Fingerhood
Newfield, NY  Zone 4/5 

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