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Tue, Sep 7, 10 at 8:42
| I have read in this forum that if a dahlia has a disease, it has to be distroyed. Then I read that dahlia viruses
(disease?) is spread by insects. Hmmm. I thought that most diseases are fungal, spread by contact,wind, water, or contaminated tools. Anyway, I've had a hell of a time this summer with sick hahlias. They are potted on my deck, in full sun, good soil, never neglected with water or food, and no, they are not over watered. Their leaves have a number of things going on. Fuzzy mold spots(mildew)which suprisingly responds minimally to a fungicide called Green Cure, mottled yellowing leaves which are limp and wilted, black or dark brown streaks through the yellowing, black streaks on the stems, and no sign of any insects. I use Bonide Orchard Sray that is usually terrific for insects as well as disease, (and sometimes I add Green cure in minimal amounts with the orchard spray) but to very little effect on these dahlias. I have cut the uck stuff away from them, although I'm losing ground and so not vigilant anymore. I want to know what it is they have, and if I can regenerate the plants by cutting them down to a short stem, prompting them to new growth....? I'm not new to dahlias, but this has me stumped. |
Follow-Up Postings:
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| There have been several reports this year of contaminated compost. Your potting soil may contains some of it. The source is herbicides sprayed on lawns and pastures. Normal composting does not eliminate it. Also, some manure products are contaminated with it as the chemical is not altered by the animal's digestive system. Dahlias are extremely sensitive to it and the symptoms you describe could be attributed to it. There is more information on the Washington State University site. They state that you can test suspected soil by planting garden peas in the soil and as a control, plant some in known good soil. If the peas have twisted leaves and other symptoms at the end of three weeks, the soil is probably contaminated. |
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- Posted by redmond_phyllis Seattle area (My Page) on Wed, Jun 29, 11 at 0:35
| I've got some issues that may be the start of what green passion was seeing in 2010. So if you find that you have this problem with contaminated soil, will it still be in the soil in 2012? I read the terminology "sterilize the soil" but what does that mean? |
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