May be Sherry. I have never had a borer but since I have been on this site I am watching for them and expecting any time for them to take over the neighborhood. LOL I keep thinking that it is not possible for me not to have had a borer and perhaps I am overlooking them. I hope I never see one.

I had a borer invasion in Chicago (area) many years ago -- have never had one here in Kentucky (knocking frantically on wood).

But I'm like you Bonnie -- looking daily for evidence of borers. Sensitivities have been heightened!!! I hope I never have to deal with them again.

I recently had two borers show up without the normal "frass" on the outside of the plant. The first clue was a fallen leaf on each plant, similar to what showed up as the first sign of a rhizome with rot.

I noticed (or , at least I THINK I did)today while cleaning up iris beds, that the cultivars that seem to have the rot are all planted directly above where the stumps were ground out last spring. Not sure of just WHY that would be? . There is at least 12"-18" of soil over the remainder of the stumps, so I doubt the wood residue rotting away below, is affecting them. Unless, because the stump acts as a "floor" under them, the drainage in those spots isn't as good . Then again ,maybe just coincidence ....Arlyn

My rot, and coincidentally borer damage, shows up in the part of the front yard that was a former cul-de-sac, left in place except for trenching for utilities. The broken asphalt and rocks were mixed with clay to make the "top soil." Drainage is not great as the excess water just hits the pavement below and keeps the "soil" wet. In the heat the pavement absorbs and then reflects the solar energy back up to the roots thus requiring watering to moisten.
Arlyn, I don't think the decaying wood is the problem, but the lack of drainage could be a possibility.