Iris borers

After having read a few questions and answers concerning iris
borers, I thought it may be a subject for a separate thread. I
have had borers before I had any idea of what they were. The
information I have read recommended two systemic pesticides,
Orthene (acephate) and dimethoate. Systemic meaning they
are absorbed into the leaves and remain toxic for all the sucking
and chewing critters. I have used acephate and it works to
stop the borers. I have dug iris and found the telltale "nick" in
the new center leaf of the fans but no damage to the rhizomes.
First application about the time the leaves are six inches or so
and another about three weeks later.

These are extremely toxic in their liquid state and the cautionary
instructions on the label should be followed carefully. Such
things as "irreversible eye damage" should not be taken lightly.

I would like to hear from others who may have a different or
better solution.

For iris borer control, imidacloprid is a very effective and much less toxic systemic insecticide. It is marketed in lawn grub control products in granular form and, I believe, as a tree spray in a wettable powder. One application in early spring just as irises are breaking winter dormancy will last all season. Imidacloprid is also the active ingredient in Advantage pet flea control products, so it has a much wider margin of safety than the chemicals you have mentioned.

Thanks for the tip. I hesitate to use chemicals that will kill anything
ingesting or, sometimes, touching them. I have followed your advice
and suggestions to others and, not to offend you, can say you are
the "go to gal" for iris information. Using comet cleaning powder on
rhizomes is something not commonly known. Helps seal the wounds
and the chlorine kills the bacteria. I always wash my rhizomes in a
fairly strong bleach/water mix before replanting.