@BookerC1, beneficial nematodes are a non chemical alternative treatment for borers which have been tested to be just as effective or even more so than systemic insecticides.
http://www.entomology.wisc.edu...
They are living organisms so they may be a little more finicky about correct application; however, I feel the timing is not as particular as with a systemic insecticide. It's usually applied before the iris flower, but you may be able to put some down now to help things a little bit. It just won't be as effective but sometimes every little bit helps.
My local nursery has nematodes that are on a sponge. They need to be kept refrigerated and used within a week, I believe. You just soak the sponge in a bucket of lukewarm water for a bit, wring the sponge out, and then put that water in a hose end sprayer or drench the iris with it. There are other ways to buy them, however, not only in a sponge. It sounds tedious but it's really just as easy as using a powder.
Since you have borers already in the rhizomes, you can dig the iris out, cut away any affected parts of the rhizome and dip in a bleach solution. I trim the fans down and dunk the whole thing in the bleach water for 15 minutes or so to drown out any borers. I've been completely renovating my garden beds, so I do this any time I divide or move any iris to prevent hitchhikers from moving to another bed. I'm not sure how many iris you have to say whether or not this is feasible to really reduce the borer population this summer, but it's a good general practice.
Then clean the iris foliage up really well in the fall and early spring but do not compost iris foliage.
