Donaldo, I haven't grown them for years, but any type of leaf spot means, you need to limit its spread and carrying it on from year to year. You should be removing the leaves towards towards the end of the growing season. Don't let them sit there to die off. Make sure the rhizomes sit proud of the soil. I would check them properly too and cut away any damaged or spongey areas. There will be a strong smell. Let it dry off before re-planting. Remove soil from the area if you do have issues with the rhizomes and import fresh soil from elsewhere.
Posts
It's my first post on this forum.
Good all round iris care certainly. I'll do my best!
Cheers!