javaMom said:partial quote........... and thanks for the crown rot information too, when will be the best time to spray fungicide as prevention ? Here we usually have wet Spring and sometimes wet Winter.
It is an on-going thing for me, especially in our torrid, hot, wet, rainy summers like the one we had this year. I like to alternate fungicides each time, and try to spray at two week intervals when possible. This month has been unusually hot, wet, and rainy here so it's important for me to keep a close watch for problems. Here is some good advice from
@Arlyn that is important to read and follow. He posted this on August 10th in the thread "Ack! My iris has fungal crown rot - what do I do?"
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" 
