I think it’s generally accepted that for breeding disease resistant roses the focus should be on using Rosa rugosa, R. wichuraiana or combining the two as was done to develop ‘Max Graf’ and ultimately the amphidiploid Rosa kordesii. What are some of the most popular rose types in recent years because of their disease resistance? They include the Meidiland landscape roses and the Kordes/ Explorer Rosa kordesii cultivars. Surprise! All have Rosa wichuraiana in their pedigree.
I’ve come to the conclusion that except for a few pet projects; for example, incorporating new colours into rugosas there is no point for me to develop breeding programs without using Rosa wichuraiana. Otherwise, it is too difficult to develop selections that have excellent disease resistance. The "lottery system’ to develop disease resistant roses is not practical for most amateur breeders, since it has to be done on a large scale to have some success. And often these “lottery system” roses that initially appear to have disease resistance eventually do not when grown in a wider range of geographical areas.
While Rosa wichuraiana should be crossed with other diploid species to develop amphidiploids, I think it would be also useful to use tetraploid species. Hopefully, some of the triploid progeny will have some fertility to use for further breeding. The advantage of using tetraploid species crossed with Rosa wichuraiana is the potential to develop new rose types because of a wider range of shrub and flower characteristics being able to be incorporated into the species hybrid. Also, some tetraploid species like Rosa spinosissima altaica and Rosa laxa are very cold hardy (Zone 1) and therefore would be valuable to use with Rosa wichuraiana that is only hardy to Zone 5. I also like the ability of Rosa spinosissima altaica to pass on its fragrance to at least F3 progeny.
We will never know the full potential of using Rosa wichuraiana in breeding programs with other species to develop disease resistant roses until the work is done. And if it is, I think the future of developing “carefree” roses of different types is very exciting.
Of the 368 roses listed in the Modern Roses XI database which were hybridized by Ralph Moore, 67 have R. wichuraiana as a parent and 52 of these have (R. wichuraiana X Floradora) as the seed parent.
10 of Van Fleet’s 18 roses in MR XI have R. wichuraiana as a parent.
If my database manipulation is accurate, 181 roses in MR XI have R. wichuraiana as a parent or grandparent (if that’s the proper term).
I agree and think using R. wichuriana more and making amphidiploids with other rose species would be of value. However, I become discouraged when I see roses like ‘Starry Night’, every flower carpet rose besides the original, most all of Moore’s roses tracing back to it, all Dr. Brownell hybrid teas that supposedly trace back a little to R. which. falling apart from blackspot. Also, ‘George Vancouver’, ‘William Baffin’ and other R. x kordesii are falling apart from blackspot in the upper Midwest the past year or two as it seems new races emerged. How much variability do you think there is within the species for especially blackspot resistance? How can we identify and obtain selections of it that possess and would transmit resistance better? Is this breakdown in blackspot resistance among its descendants indicative of single gene resistance that can more easily be overcome relative to more horizontal resistance with many genes all having a small effect and it would be more difficult for a pathotype to overcome them all?
I’d love to learn your thoughts and how this can practically be approached doing what one can along the way to have a greater probability for success in the end.
Paul, Rick and David,
I agree that Rosa wichurana (or traditionally wichuraiana) has a lot of potential still. It’s a very useful rose for a hybridizer. I just don’t think “it’s a good idea to put all of your eggs in one basket”. I’m working with Rosa wichurana, trying to incorporate it into some diploid hybrids; but I’ve noticed exceptional disease resistance in some other species hybrids also. I think the more disease resistance genes we can gather from diverse species, the better off we’ll be. How about Rosa soulieana (-supposed to have disease resistance genes), Rosa davidii (-from which supposedly came blackspot resistance in “Baby Love”), some of the native North Americans (setigera, arkansana, virginiana, carolina, californica, woodsii, gymnocarpa) and a host of Asian species that have not been explored in breeding programs. I also think Rosa wichurana is great, but there is so much more out there for me to experiment with.
I feel like I’ve only scraped the surface, and already I’ve seen great examples of disease resistance other than Rosa wichuarana. Check out some of the species crosses in the following table (some of the especially healthy ones would are rugosa X carolina, rugosa X palustris, palustris X moschata and if the rabbits would let it grow - arvensis X soulieana)
Lady Banks also seems a good potential for black spot resistance, although very little has been developed from them. But as the single fertile version of this rose circulates more, I believe we may see some more lady banks hybrids. I have obtained “The Pearl” and have made some crosses with it with pollen of any roses I could find blooming. I’ve used Livin Easy, The Fairy, Renae, and Baby Love for the pollen parents in the mean while. I’ve made a most intresting cross using the pollen of The Pearl and Tigris as the seed parent. Since Tigris is in its first year, and I’m not getting a lot of flowers, I’m not expecting seeds at all, although it would be very nice If I did, and even more if they germinated…
Re ‘Baby Love’. I’ve had the opportunity to watch roses in the no-spray garden in Asheville NC and they are serious no spray, using only limesulphur dormant strength in midwinter for a clean up.
They had two ‘Baby Love’ and the larger was magnificent until it came down with a fungus (probably Black Spot) and defoliated completely and never recovered. The second , not adjacent plant missed the problem. In the case of the first plant, its problem wasn’t high disease pressure in the vicinity- roses around it were clean, but some strain came by and knocked it out and because of the defoliation, out of the garden. The second, smaller plant remains.
Ann–I second your observation of Baby Love. I had high hopes for it, but it has shown little if any resistance to whatever strain of Blackspot I have here in my Atlanta-area garden. If the disease resistant genes are in there, this particular iteration of them doesn’t seem to express them very well based on my experience. But, to continue the idea above, a few of the Brownell R. wich. derived roses have proven stellar in this regard, especially Orange Ruffels. I grow every Brownell variety I’ve been able to get my hands on so far, and as a whole they do seem to be above average in terms of disease resistance (even the yellow V for Victory).
Baby Love, Rabble Rouser and Pretty Lady have been black spot for me to date here in the PNW. I dont think they are the end all, though. Banksia seems untapped. I really like the californica foliage although it is no where near immune. Above average Id say. Wichurana seems nice. Never had personal experience. It seems small, though. I want to try the bracteata that Richard Baxter sent me next year. Definately with dwarf roses though haha. Leonie Lamesch seems like a good combo idea.
err, black spot free I mean.
Regarding my focus on using Rosa wichuraiana, from my own work and what I have learned of the general development of roses, all the other “eggs” have been broken and now there is only one left. Perhaps there is potential to use other species hybrids for disease resistance, but it is doubtful if any will surpass Rosa wichuraiana.
In my opinion, generally speaking North American species are not that disease resistant. For example, you mentioned Rosa arkansana; it is susceptible to rust. I would be more inclined to use the tough European/Asian species like Rosa laxa and Rosa fedtschenkoana in breeding programs for disease resistance.
But really, the big problem is breeding programs with the goal of developing roses on steroids. If there is a more beautiful rose than simple Rosa spinosissima hybrids, rugosas and gallicas I haven’t seen it. By keeping breeding programs relatively simple and not incorporating Hybrid Teas/Floribundas into them, it maximizes the chances of breeding disease resistant roses. However, I doubt many amateur breeders will take that route. The marketing programs of professional rose breeders and rose growing organizations like the American Rose Society influences rose growers and breeders that a certain type of rose, namely Hybrid Teas/Floribundas is the standard. As a result, amateur rose breeders are striving too much to breed disease resistant roses when it is impossible to do so.
I’ve noticed that Rosa wichuraiana has it’s faults too. It often is disfigured by some strain of mildew here on the mid-Atlantic coast. I don’t think you’ll ever find a species that is resistant to everything that attacks roses. I’m not saying that you should reevaluate the value Rosa wichuraiana still has for hybridizer’s (especially amateurs as you’d mentioned). I’m only hoping that you’ll leave a little room in your heart for the rest of the often-forgotten species. I am glad to see that you do recognize a potential in the European/Asian species. I have Rosa davidii (tetraploid supposedly) and Rosa beggeriana (unsure of ploidy), both of which I’ve got big plans for.
As for the modern Hybrid Tea/Floribunda crowd, they have their appeal; but I have to agree…I think that an amateur rose breeder (like myself), can do so much more by working with species crosses. But I can’t help myself, and sometimes I do cross a species with a modern. I hardly ever cross a modern X modern…I can’t remember any offhand…I just don’t think the typical product of these crosses is healthy enough for my growing conditions (tough environment and lots of neglect).
Well, good luck travelling your wichuraiana route. I especially look forward to seeing your results in combination with other species. Since it seems that mostly it’s been used with moderns in crosses.
I am pretty sure that I had read that the Canadian Government rose hybridizing program was actually a very small program - the number of seedlings were in the hundreds not in the thousands.
If this is correct, then there should be plenty of hidden gems still available in their genes. One of my main approaches has been to cross the Canadians with themselves.
I am also crossing the Canadians with the Kordes roses and the Buck roses. The idea here is to introduce additional flower forms without sacrificing too much in disease resistance and winter hardiness.
Since the Austin rose Heritage has been disease free and winter hardy in my garden and since it has a very beautiful flower, I have also utilized it with the Canadians.
I am also working towards introducing genes from tetraploid forms of original diploid species or near species roses into the “Canadian-Buck-Kordes” roses.
Finally, I have been using Peter Harris’s yellow tetraploid R-15 in an attempt to introduce additional hardy yellow genes into the “Canadian-Buck-Kordes” rose gene pot.
Yes, you are right. The Explorer rose breeding program was a relatively small one. In a typical year, there would be production of few hundred seedlings. Since it was never done or at least no cultivars introduced from the efforts, there is no question that there is a lot of potential by crossing the Explorer Rosa kordesii cultivars with themselves. You have taken the lead in this respect. I suspect though that the Agriculture Canada rose breeding program at Saint-Jean-sur-Richelieu, Quebec is probably doing the same thing. This three year breeding program is a partnership between a consortium of Canadian nurseries and Agriculture Canada and ended in March 2004. I do not know if it has been renewed.
I also agree with your strategy of crossing the Explorer Rosa kordesii cultivars with the Kordes Rosa kordesii cultivars, which I think was overlooked in the Explorer breeding program. But more work should be done with Rosa kordesii or the Rosa kordesii L83 germplasm to increase the gene pool to breed with Rosa kordesii cultivars. For example, I would like to see a Rosa kordesii x ‘Silver Jubilee’ breeding line developed. ‘Silver Jubilee’ already has Rosa kordesii via ‘Park Director Riggers’ in its pedigree. What about developing some Rosa kordesii x David Austin roses breeding lines?
While it is not readily available from nurseries, ‘Amsterdam’ (‘Europeana’ x ‘Park Director Riggers’) might be interesting to work with because the parentage is 1/4 Rosa kordesii. I have read that it is susceptible to mildew though and know nothing about its fertility. But I have access to plants of it.
I got seedlings from Sympathy x Falstaff this year Paul. No blooms yet though but I plan on trying Rosarium Utersen with one of the Austins.