I seem to remember that the main reason Paul Black left Oklahoma was a wicked case of scorch, where he lost almost all of his stock, and that he later said that if it is true scorch you should probably just get rid of the rhizome(s). Does anyone else remember that?
I thought I had it the first year I potted up a bunch of iris and put them out in the sun and watered them in the middle of the day (what a fool I was!), but I think it was just stress on the plants plus the beginnings of bacterial soft rot. I learned later that that was the worst thing I could have done, because in our 100+ summer temps and watering them in the sunlight they are really susceptible to soft rot. Heat and moisture, plus too much nitrogen, really encourage soft rot. But I had many where the center leaf turned brown and that's why I thought it was scorch. After I lost a couple and did some reading we created a plywood table on sawhorses and I put the pots under a shade tree -- and I've had great luck ever since!
