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why black spot magnets are magnets.
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Posted by whitejade z5 MI (My Page) on Sun, Jun 5, 05 at 10:39
| I am fairly new rose care, so I've been researching a lot (which garden web has been immensely helpful for!) and keep hearing that the new hybrids, etc are known to be very bad for black spot. I did plant my first Austin rose last fall, *before knowing how "magnetizing" they were for fungal problems. So far, pretty good however, the rose came to me with both a bit of black spot and powdery mildew. (yeah I know, why would I buy a plant and put that into my yard right? well, I figured I could brush up on black spot and it'd be ok or tolerable at least - AND the flowers smelled like heaven to me too, of which there were a ton on this plant, even that it was in a pot :)
But why are so many modern roses said to be black spot magnets? Is it the current breeding programs perhaps? Is it that breeders may be breeding in soil that was too N-P-K'd and not biodynamic enough? (seems to me that most of the population is still using chemical fertilizers and npk as their standard)
And does anyone know any rose breeders who are into biodynamics or other such organic / sustainable practices ? |
Follow-Up Postings:
RE: why black spot magnets are magnets.
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| Actually many of the old roses are quite bad for black spot-- most of the long-caned Bourbons and Hybrid Perpetuals are as bad as, or worse than, the average Hybrid Tea. As soon as people started selecting seedlings for better or more unusual flowers, rather than self-sufficiency, disease resistance declined. Modern breeders do pay some attention to disease resistance, but major American breeders are basically selecting roses for the California climate. Or, David Austin Sr. admitted that quality of bloom and growth habit took precedence over disease resistance. Some of his are not so bad, though, and there is a trend of improvement in the disease resistance of Austin''s releases. Many of the shrub roses bred by Kordes and Meilland in Europe have good resistance, as do some of the Griffith Buck roses, John Clements roses, and Ag Canada releases. In your climate you should consider the old Alba and Gallica roses and old rambers, which are easy to grow and make a tremendous show in the long first flush, which fills a good part of your growing season. |
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