I have one that is covered too. I scrape the leaves with a credit card and then wipe them with my wet hands. (pretty much a no-spray garden)

They've never spread to any other plants and some years I don't have any at all. This particular iris is semi-shaded and not getting air circulation.

Me too! I have never had them on irises. My mom has them too, and so does one of my gardening buddies. Weird. I wiped them off and bagged the old leaves and threw them away. You can cut back the infested foliage if you wish and bag and toss it at this time of year- it generally does not affect next year's bloom, at least not here in Southern California.

Thanks, I like the simplicity.