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Abgeschickt von Chuck Sheviak am 22 Juni, 2000 um 15:27:27
Antwort auf: Cypripedium acaule leaf disease (help needed) von Paul P. Perakos am 10 Juni, 2000 um 00:03:59:
Paul, exactly the same thing happened to me several years ago here in Upstate New York. I had had a large group of C. acaule for many years. The plants had increased in size and number as seedlings appeared and grew into flowering plants. They were grown in a specially excavated and prepared bed somewhat isolated from the surrounding soils. The whole thing was very successful.
Then during a very wet summer, the same leaf symptoms that you described appeared at one edge of the bed and gradually spread across the whole colony. Many plants died-down, but a change in the weather to droughty late in the summer saved part of the colony. I hoped that the following year if the weather were more favorable the plants would recover. I removed all traces of leaves in the fall and had them carried away with the garbage. Unfortunately, the better weather of the next year did not help.
My experience convinced me that the problem is not a leaf infection, but a systemic spread of a root pathogen. From the rate and pattern of spread, I am certain it is a fungus. In my case, fungicides were ineffective (I can't remember now what I tried), so the second year I dug up the surviving plants, removed all the soil from the area and started over with new soil. I thoroughly washed the remaining plants, removed all unhealthy tissue (leaves and roots), and replanted the cleaned plants in the new bed. All eventually died, although a few hung-on into the third year.
Sorry to be so negative, but I doubt there is anything you can do.