I also prefer using beneficial nematodes. Milky spore powder can also be used for japanese beetle grubs in the lawn as well as iris borers.
Cleaning up the foliage is an important step as is avoiding putting iris leaves in the compost bin. I just read an article posted that recommends cutting all iris foliage that wasn't removed in fall down to the rhizome in the early spring instead of only the brown and dying foliage. Has anyone tried that? I think I may give it a go next spring. I would usually trim the foliage down in the fall and then just pick any dead leaves off in the spring.
