Question
QUESTION: Hello,  I have grown rohdea in several varieties for several years.  I have a perpetual problem however with yellow spots about half an inch in diameter having a brown center.  They spread to more spots and theleaves eventually are badly scared and die back.  It is a testament to the plant that new leaves come and are healthy and later succumb.  The plants move out of my greenhouse in the spring and in in the fall. They are cleaned up and disease removed but it comes back. I have tried fungicides and looked for pests but don't see any.  All of the dense literature on this plant seems to be in japanese.  im stumped. Im hoping  that your knowledge base and research base can help me.  Thank you, Allen Berry

ANSWER: Hi Allen,
Thanx for your question.  Sorry to take so long in getting back to you.  I should have put myself in vacation status for the holidays.  I hope you had a happy New Year.  Are you moving the plants from the greenhouse and then back into the soil?  You may be moving plants back and forth in contaminated soil.  Some viruses and funguses can live for many years, undetected in the soil.  If you continue to have this problem, I would not keep putting the plants back in the same place.  These plants are supposed to be very pest and disease resistant.  What kind of environment are they in, in the greenhouse and when planted outdoors?  Wet, warm, dry?  Also, if you are moving them back and forth an the area may be contaminated, you should sterilize all of your pots and planting area in the greenhouse.  If you would get the answers for me from my questions, I'll keep digging for more info.  So far, I have found nothing concerning major diseases or pests of this plant and you're right, the info is scanty and several websites in Japanese.  I hope this helps.
Tom

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rohdea disease   QUESTION: Thank you Tom for pitching in on this.  These are solely potted plants going in and out.  If there is a soil drench that might work I would be happy to try that.  I don't know how to sterilize my greenhouse but I see your point and clearly the problem could be in the soil of the pots.  What then?  It doesn't seem to matter whether they are outside and growing, they get it, or inside and growing, they get it.  My winter green house is cool, about 50-55f. I have tried water from the top and the bottom without difference.  Just today I sprayed with a fungicide and disease solution.  I will email a couple of photos if you give me an address.  I can't do it from this site.

Answer
Hi Allen,
Thanx for the additional information.  I saw the picture of the plant.  Everything I have read has indicated that these plants have no pests or diseases.  I'm not so sure this is a fungus.  It may be a virus and if that's the case, there probably isn't much you can do about it.  The one thing I can suggest to you is to take a sample of it to the horticultural agent at your local county extension.  I know when I was associated with the Master Gardeners here in Kansas, we had clients come in with samples for our agent to look at.  Anything he couldn't figure out was sent to Kansas State University for further analysis.  If you give me your city and county, I can get you a contact.  I hope this helps.
Tom