This is offered only from my personal experiences. I am sure sure there are plenty of "borer experiences" out there. This is
not an endorsement or recommendation of any commercial product. At one time Ortho offered a product known as a "systemic insect killer". That was several years ago; and I think the EPA has (had) ruled against it. It is no longer available that I am aware because of safety concerns. Long story short; Bonide had a product last year which was available. Now Bayer has the granular form available which I have (and still do) use. This has been mentioned in Tom's post above. It sure helps me.
Borer control is an ongoing fight for iris growers in the eastern U. S. & Canada. The last time I checked borers are not found in the western states. No matter what is used I highly advise reading the directions for use; especially the fine print which I can barely read. Safety in using insecticides is critical. Here is something I wrote back a few years ago. It
might be useful to someone out there.
https://garden.org/ideas/view/...
Some product pictures that I (previously) or still use.
