Hybrid Rosa virginiana X Princesse du Ballet ( Hybrid Multiflora/ Hybrid Musk). Flowers well with very good fertility, foliage is excellent.
1 Like
Phillip,
Iâm breeding specifically for the southeastern US, where blackspot is a huge problem. R. palustris, which will happily grow in standing water, is highly resistant to BS. Another thing I like about palustris are the long sepals and that the buds are covered in sticky glands that have a really nice scent. The flowers are lightly fragrant. If you do acquire it, make sure to give it plenty of room or contain it with a root barrier as it will sucker in every direction. While it can handle soggy soils, it will also grow in well-drained areas.
Kim, I love the foliage on âFaith Whittleseyâ x Rosa x Actii, it reminds me of sinowilsonii.
Warren, I really like your R.willmottiae X R.forrestiana! Nice.
-Jonathan
About R. palustris. I have little personal experience with it, though for decades I grew a plant that I brought from western PA that was probably it. I dug it out of a hillside bog there. May still be out in my wilderness though this yearâs drought may have done it in. Never got enough seed to get germination from my few attempted crosses.
However, I just planted out several dozen new germinations from seed that Jon Windham sent me last Dec. Probably he had 5 distinct clones in the lot and I pooled the ones that sprouted June 24= 5 + months in stratification. But some clones pop sooner than others so it is biased toward one or another. ONe of the fastest started sprouting a month earlier. Some are yet to begin. Wonât have full data for another 6 months to a year. In the meantime, if you want half year seedlings next spring contact me at the e-mail address up above in the discussion of 13-1, or on another thread of R woodsii. I still have woodsii after sending some out this past spring if youâd like that one too.
Kim, I do like the look of that foliage. (Except for the ability to showcase a contrasting or complimenting bloom, I wonder if the average consumer ever even notices a roses foliage. Iâm wondering when I started noticing/caring.)
Warren, youâve got another beauty there as well. I definitely have R. carolinia or R. virginiana on my wishlist thanks to you. (Donât recall why, but I think Iâm gunning for the southern species â seems I read something that has me thinking something in its evolution might be more useful to my aspirations.)
Jonathan, have you been working with palustris for a while? Iâm wondering what happens to that packed panicle in future F1âs depending on the mating. As I say, R.p. was on my theoretical wishlist years ago when I lived in New Orleans, but I donât even recall what I learned about it at that time. I was wanting to attempt to cross it with something comparably xeric, but was very new to all this, and had no real knowledge of what I might select to mate it, nor why.
Larry, if there is some way I can repay you, I might take you up on that. Thank you, sir.
The postage is only 7. 50 or so for a small priority mail package. By winter these will not be all that big. A couple dozen easily fit inside. Pot them up, select the first to bloom, or one with fewest prickles, or best foliage or whatever. Blooms might take a couple years if they are like other species Ive grown. I donât know for sure but I guess that individual closes are self-fertile or the hip yield wouldnât have been so big in the Clemson area at different locations. For sure my rose from PA had not partners but ti produces hips. Just not one with germinable hips from tetraploids pollen donors. For me the interest was in winter hardiness. For you thatâs immaterial. SC is closer to LA than PA is in terms of latitude.
Thanks Jonathan the R. willmottiae X R forrestiana has been a blessing for me.
Thanks Phil, the Hybrid virginianaâs do well when crossed with dioloids, this one is shaded by R tunquinensis and the Hybrid R. davidiiâs and grows very happy with those conditions.
Cheers Warren
What about the section of Spinosissimas known as the Scots roses? They are tetraploid, black spot resistant. David Austin, Knud Petersen, to name just two, are producing repeat flowering Spin hybrids.
Some of the Canadian Spin hybrids (a mix of ploidies) are producing remontant hybrids - Prairie Peace stands out.
Stephen
Some of the Scots roses are already rebloomers: âDoorenbos Selectionâ, for example, blooms continuously. âOrmiston Royâ, grandparent of âGolden Wingsâ, is descended from âHarisonâs Yellowâ and inherited the bright yellow color. It reportedly reblooms some.
Doorenbosâ selection is one of which I have only learned this past year. It is also purportedly one of the more successful in the deep south, and definitely on my list to acquire at some juncture. Is it also tetraploid?
Stephen, I think a good number of Basyeâs roses have some altaica somewhere in their lineage, including Carefree Beauty. Iâve wondered how much they contributed to the overall health, or if cold-hardiness was the prominent feature for which they were usedâŠ
Warren, thanks for info on shade tolerance. That makes it more enticing.
Philip;
Canât remember where I read this but I believe I read that cold hardiness and black spot resistance were possibly âgeneticallyâ linked. I have no idea if that is verifiable but it is the reason Iâve invested in adding cold hardy roses to my middle GA zone 8b garden. I donât get enough cold to get Gallicas, Albas, and most Mosses to consistently bloom but Rugosa hybrids, Harisonâs Yellow, R. hugonis, xanthina, primula, and other members of the Pimp. family are doing well. Just added Prairie Peace, Madelineâs Choice, and some other hybrids descended from Altaica. They are hanging in there in this pretty hot summer.
Stephen
Three species I am intrigued with and donât know much about are R. blanda, R. gymnocarpa, and R. webbiana microphylla. First 2 I can find commercially in the U.S. but the last one is a bit difficult to locate here.
Black spot resistance is found in some roses that are not especially cold hardy:
American Rose Annual, 16: 45-51 (1931)
Breeding Better Roses
Rev. George M. A. Schoener, Santa Barbara, Calif.
Only recently, Peter Lambert, the well-known German rosarian, asked the question: âHave you ever seen black-spot on R. bracteata, R. sempervirens, Cherokee?â He might well have asked also: âHave you ever seen mildew and rust or brown-canker on these species?â And still further, to these species he could have added R. gigantea, R. macrocarpa, the Banksia roses, and several species only found within the last thirty years, such as R. bodinieri LĂ©veillĂ© & Vaut; R. gentiliana, LĂ©veillĂ© & Vaut; R. adenoclada LĂ©veillĂ©; R. lucidissima LĂ©veillĂ©. All these newer species have more or less persistent, healthy foliage, glabrous on both surfaces. To these must be added several subspecies of R. gigantea, practically immune to those evils so prevalent upon the newer Hybrid Teas and Pernetianas, the two types mostly used in gardens and most abused by inbreeding. Because certain types of roses are nearly immune to these ravages it ought to be plain enough that through carefully guided breeding a gradual elimination of them is possible.
http://bulbnrose.x10.mx/Roses/breeding/Schoener/SchoenerHealth1931.html
Black spot resistance is found in some roses that are not especially cold hardy:
American Rose Annual, 16: 45-51 (1931)
Breeding Better Roses
Rev. George M. A. Schoener, Santa Barbara, Calif.
Only recently, Peter Lambert, the well-known German rosarian, asked the question: âHave you ever seen black-spot on R. bracteata, R. sempervirens, Cherokee?â He might well have asked also: âHave you ever seen mildew and rust or brown-canker on these species?â And still further, to these species he could have added R. gigantea, R. macrocarpa, the Banksia roses, and several species only found within the last thirty years, such as R. bodinieri LĂ©veillĂ© & Vaut; R. gentiliana, LĂ©veillĂ© & Vaut; R. adenoclada LĂ©veillĂ©; R. lucidissima LĂ©veillĂ©. All these newer species have more or less persistent, healthy foliage, glabrous on both surfaces. To these must be added several subspecies of R. gigantea, practically immune to those evils so prevalent upon the newer Hybrid Teas and Pernetianas, the two types mostly used in gardens and most abused by inbreeding. Because certain types of roses are nearly immune to these ravages it ought to be plain enough that through carefully guided breeding a gradual elimination of them is possible.
http://bulbnrose.x10.mx/Roses/breeding/Schoener/SchoenerHealth1931.html
no more
To provide an answer to part of the above question, yes, I have observed mildew on established, large Banksiae lutea numerous times. We had one at the Encino home which topped an enormous stand of Golden Bamboo. It grew through the stand and covered the top. People used to bang on the gate to ask HOW we got the bamboo to flower. Both existed on the ground water and received no supplemental irrigation other than rain (when that happened). The lutea flowered a long time in spring and often provided flushes several times throughout the year because of the climate. Between the water stress due to the bamboo competition and the constant bath of transpiration from the bamboo, that plant usually had rather heavily mildewed newer shoots. Add that Banksiae seedlings are EXTREMELY susceptible to mildew for a very long time, until they mature out of it (meaning they achieve sufficient root and top mass to resist it).
I remember reading in Raoul Robinsonâs âReturn to Resistanceâ that vertical gene-for-gene resistance arises in seasonal climates where every spring is a new beginning in terms of infection, while temperate all-year climes gave rise to horizontal resistance since the infections could happen all year long. Iâm not real clear on exactly why this happens. It could be why tropical roses like R. gigantea and R. laevigata have such excellent resistance while Ross Rambler, R. glauca and other hardies are total dogs. R. carolina and R. virginiana seem to have developed good horizontal resistance while maintaining pretty solid winter hardiness.
I too was going to suggest, Stephen, that the generalization you mention seems counter-intuitive.
If Iâm not mistaken, BS is a disease of warm wet climates, whereas for instance, mildew is more common in cooler humid (but less rainy) weather. It would seem then that roses of warmer wetter climates with longer growing seasons would, of necessity, have persistent foliage which is resistant to BS. Roses from more arid regions might be expected to drop their foliage at the first signs of stress â to, for instance, preserve precious moisture in the event of extreme drought â and would not require a cuticle with high fungus resistance. Montain species, from cooler humid regions, it seems to reason might be expected to be more resistant to mildew. I think this reasoning is moderately well born-out in reality. Banksias are often classed with Chinas, and as warmer, wetter region species, they are generally a bit mildew-prone in climates that are conducive to such. In the Gulf Coast regions, this is almost never noticed as the climate is generally not conducive to mildew. Banksias are considered to be essentially disease-free in that region, despite their propensity to mildew in cool coastal fog of CA, but if a Californian tells a Gulf Coaster of a disease-free rose, the said person in the SE should be highly skeptical. The cultivar might be a relative BS farm.
Joe, I think you are essentially correct, though I seem to recall that both you and I got chastised for using the terms vertical and horizontal to mean high-resistance to single strain, and multiple strain resistances respectively. 
(Okay, vert and horiz are a lot shorter to type! LOL)
The story goes that Dr. Lammerts thought he had whipped the problem of BS. But when he moved his nursery from Livermore to the Watsonville area, his most resistant cultivars got the spots. Different climate, I suppose, and probably a different soil.
A woodland species, adapted to acidic soil and shade, will not be at its most resistant when forced to endure alkaline soil and full sun.
Another matter is the length of growing season. Some nutrients (minerals, proteins and such) are packed into the developing leaves and must last for as long as the leaves endure. A greater supply of nutrients allows a leaf to resist infections longer, but also makes it more attractive to herbivores. Trade-offs are all around.
Iâm starting work with R. woodsii âKimberlyâ. From HMF:
âIntroduced 1998. A selection of Woodâs rose from the wild near Kimberley, BC, by W. Nicholls,
UBC Botanical Garden. This vigorous clone exhibits compact growth with glaucous leaves, red
petioles and young stems, suckering and superior flowering compared with typical forms.â
Iâm assuming itâs a diploid. So far, Iâve crossed it onto Bella Nitida and that resulted in a small shrub that hasnât bloomed yet. It also appears to self-fertilize. Could be hardy to zone 2.
This one is perfect for me as Iâm working towards very hardy smaller shrubs with good disease resistance