Bobert and SRS, the iris deaths is a mystery. They are in a well drained area, winter wasn't that bad this year or last. There doesn't seem to be any associated bugs or holes, and it doesn't even look like a fungus. The nice, fat roots just go to mush, like a bad sweet potato. Could a mole eat/tear away the little 'feeder' roots and kill them that way? We just started seeing (starnosed) mole holes a couple years ago, so I'm not familiar with any damage they might cause.