Jane this is a photo which LOOKS like crown rot, but in fact it is borer damage. If you look to the right of my thumb you can see the borer hole. I post it because it looks similar to crown rot. Arlyn had posted some information here concerning crown rot which I feel is critical to iris gardening. I post it here as a quote because it is very helpful to everyone.
crowrita1 said: I might add that any fungal problems are much easier to "prevent", than they are to "cure", so, try to get the beds "ship shape" before the wet, warm conditions start, and make "prophylactic " sprays of fungicide. I use 4 different fungicides ,alternating them, and make applications about every 10 day-2 weeks, starting when new growth starts on the plants....but, that might be "over kill" for your climate conditions 
. Another thing I do...usually....is to add "half strength" Miracle Grow to the fungicide "spray application" that is made about 2-3 weeks after bloom has ended....the iris foliage is at it's "rattiest" then, and the plants are beginning to come out of their resting period....what this seems to do, is cause them to have a "growth spurt", and push off a lot of leaves, over a real , short period of time....which makes for a huge "clean-up", but, it gets the plants "looking good" pretty quickly. It's something I learned from a couple commercial grower's sites, and, it does work, but....my "collection" has grown to the point that, it's a BIG job !! This year, I only did it in the rebloomer beds, as besides "more iris", there is also "less energy and time" 
