Found a quote from Paul Black on the subject:
"The answer is an emphatic and unequivocal - dig it up and get rid of it. Trust me, I have vast experience with the beast. If it is scorch, when they dig them up, the roots will be shriveled; if it is frost damage, the roots will still be plump. It is an insect vectored disease which means it is spread by leaf hoppers and aphids. If left in place, the plants serve as a reservoir of infection. The insect feeds on an infected plant and spreads it to uninfected ones. It is just like Dutch elm disease and other similar "wilt" diseases. There are probably ones that are infected now that don't yet show symptoms but that will as time goes on. That is what makes it such a nasty disease. It can be spread from plants that one doesn't yet realize are infected - sort of like the latency period in AIDS. The only way to destroy the organism in the plant is to dig it up and heat it to about 110 degrees F for at least 24 hours. I would do this only if it is a plant that is of great value. If the plants are in lush growth, they stand as good a chance of rotting during treatment as recovering. Each of these gardeners has my utmost sympathy and empathy. One of the best solutions is to plant the irises among other plants as in a mixed border. There is nothing that disease likes better than to have all its victims lined up shoulder to shoulder. Mid-America Garden Paul Black
Forgive the pun but "it is Scorching in Kansas"! Region 18 Spring Tour hosts, Hutchinson Iris Club is also reporting scorch in their Guest Iris beds and are very concerned about it....
When scorch appears in a clump it spreads from rhizome to rhizome. If the rhizomes are connected, I first immediately cut and separate the afflicted rhizome from the others. The afflicted rhizome can be heat-treated by placing on concrete or asphalt in full sun and baked for a couple of weeks. They will look dead but when replanted they almost always live. You just lose any bloom that was already inside the rhizome. Jim Morris, Region 18, St. Louis, MO This expert advice, others, will appear in the next MIS publication The Medianite in the "Ask The Iris Vets" column. Persistent problem in the Midwest especially after a winter like this-too warm, hateful cold, dry = stress! Rita Gormley "
