Like everyone else, the rot I have had no smell and didn't seem to affect the starts, so I was able to rescue those. Only one of mine had the fan fall over, and since I found it after being on vacation, the rhizome was too far gone to save.
The first iris I found with rot this spring was in a full sun garden, and none of it's neighbors had any rot problems. I had covered the rhizomes with pine boughs, and wonder if it just made the garden too wet for that iris. It had lots of starts so I now have it growing in 3 places. A couple of it's neighbor rhizomes had a bit of shrivelling but this didn't affect the growth or bloom.
The second one to go had just been planted (July), and was in a sunny location so no water issues. I had a new organic garden mix added into that bed, which is the only thing I can think may have been the rot source. This is the one that had the fan fell over. The last one was new too, and it looked great, then the leaves yellowed and the rhizome got soft. I dug this one up and potted it and really tried the Comet treatment. Comet had little effect. I would spoon out all the soft rot, then sprinkle with Comet, but after a day or so more spots on the rhizome would be soft. A solution of beach and water a bit stronger than the suggested 1 to 10 ratio worked very well (about 3/10) stopped the rot finally , but it only has two very little starts left (about an inch high) and they are growing very slowly. I think it was the victim of the same soil mix. So Arlyn - you may be right to suspect your "organic" soil.
And I plant mine with the top of the rhizome exposed like many of you. Some of the old iris in my yard got buried by about an inch of dirt or so and bloomed sporadically. Once I reset them with the rhizome exposed they went to town and have increased and bloomed ever since.
