Looks like the crown rot is what I had too. I dug them up and cut away all of the rot, plus a little extra. I gave them a diluted beach bath and with the smaller tiny survivors, I gave them a soft toothbrush scrub of diluted bleach and dipped all of the rhizomes into a small bucket of Comet and tapped them against the side to shake off any extra. I placed them upside down in the sun to dry and now have them in the barn to sit for awhile longer. I'll pot them up and replant the larger ones in October. I also tossed out the soil that was under and around the infected irises. Then soaked the holes with diluted bleach water and covered it with Comet. Afterwards, (while wearing some gloves) I scrubbed all of the tools and work table with a stronger bleach solution (about 30%).
I had this same rot happen last September on new irises that were just planted. We had a late nasty heat wave and that didn't mix well with the new wet iris beds. It's in these same beds that the problems are popping up again. Anyway, the treatment I did above saved quite a few of the irises last year.
The drip line error was an oopsie and a new learning experience for me.
