I would doubt that any correlation between shade tolerance and disease resistance would actually be genetically linked. The sheer numbers of genes that effect both those traits would make that all but logically impossible. I would suspect that they show up together in roses more because both traits are closer to the species type than a highly breed type of rose. In other words, wild roses have to rough it, and bloom and reproduce without human help. So they have to be able to stand less-than-perfect conditions, like shade and disease. When we start breeding any plant over a long period of time, we focus on the traits we want, and allow the plants to develop weaknesses. Not that humans specifically select for shade intollerance or disease prone roses, but because we pamper our favorite plants, we allow those generally “weaker” phenotypes to grow and reproduce when Mother Nature would have weeded them out. So one would expect shade tollerance and disease resistance to go hand-in-hand, just because the way roses have been bred for much of their history selects against both traits pretty much equally, but I wouldn’t expect a breeding program focused on one of those traits to necessarily bring the other along with it.
That having been said, I think that breeding for shade tollerance in and of itself would be a great idea – I know a lot of gardeners who would love to have more shade-tollerant roses, and it seems to be an area not much focused on by rose breeders in general.
Sorry that was such a long answer! I couldn’t think of shorter way to say it.
I think that any rose can grow in the shade, really - but if there’s a disease that can attack it, then it is more likely to be severe/fatal in the shade. My limited observation is that a rose that tolerates shade well is just a very disease resistant rose, period. I could be wrong, but I can’t come up with any examples of roses that follow a different pattern.
This is quite interesting!
Hybrid Perpetuals are shade tolerant, they indeed need
partial shade, the reds even more.
So…Roger Lambelin is therefore a very disease-resistant
rose, isn’t it?
Perhaps I should qualify - based on my personal experience - roses that perform well in shade, in humid zone 9, without any chemical intervention. That is a very short list and they are all very disease resistant.
But: I am in zone 8 very humid Belgium, I never spray,
and the HPs perform like big winners here in partial shade…
That’s really the crux of the matter: most roses that are disease resistant in the shade are only so in particular climates or microclimates. A southeastern American zone 9 feels practically tropical to a human (and presumably, a rose); a soggy zone 8 Belgium is most definitely temperate in spite of having a winter minimum temperature that is technically only ten degrees colder. Once you learn to grow roses in the shade where the summers have subtropical heat and humidity but the winters put parts of Siberia to shame, then you will know the meaning of the word “perspective”! : )
This is precisely why we cannot generalize our own
My “terroir” is a quite special one -like the vast majority of the others!-.