as well with Sherry, I have it some years worse then others, but I have never done anything about it. Wetter years it seems worse then dry ones. It usually shows up here about mid way through the bloom season. This year due to the very hard late frosts, I have many of the leaves twisting and turning in a wonky sort of way, some of the ends of the leaves have died back. Others have lost their terminal bud. Iris are generally tough. Sometimes, I think, we really do more damage then good by digging and prodding and constantly replanting an already weak rhizome.