I too have noticed some rot this year. Guess it is good that I just completed an "iris only" bed and am moving everything. It is giving me the opportunity to clean things up, and start "fresh" Only noticed one with an Iris borer, and it was in a bed by itself, so hopeully there are no more surprises like that, Urg.
By the way, with just me living in the house anymore, I don't plant much of a veggie garden anymore. Which means that the single tomato plant tends to get popped into my front daylily bed....
Of course, my asparagus bed is full of daylilies for some reason
Jan