Disease problem? Or?
I was doing the mid-summer pruning and cleanup of my front garden. When I got to my tall bearded irises, I patted myself on the back for their robust good health. They bloomed well this spring, have faultless, unmarked, healthy leaves, and are spreading vigorously. As I pulled off the withered old leaves I discovered that the roots of several were quite mushy. At first I thought it was just a case of too much mulch -- and that indeed may be the cause. I did see some holes in a couple of rhizomes near the stem, perhaps as large as a quarter. When I peeled off outer leaves the root under that was clean and whole. I observed pillbugs but no other kind of bug in the soil.
Is this likely to be just too much mulch keeping the roots too damp, or do I have a more serious problem? I dug up the plants that had mushy rhizomes and discarded them. Healthy looking rhizomes attached to them I also dug up and cleaned to dry, set in the shade (it's in the upper 90's here) and cut the leaves in a fan. I plan to replant them in a day or so. Several irises that looked healthy I left in place.
Please advise if I can replant in the same area or should move them to a new one. Also, do I need to soak the rescued rhizomes in a bleach solution before replanting? And ought I to remove the irises that looked okay to another spot?
Thanks for any advice.