Now it is time to break the bubble of various roses.
-John Davis not even slightly resistant to blackspot making it weak to winter kill. I knew that this rose was bad from Terry R but it is worse than even the worst Mordens.
-Martin Frobisher blackspot magnet and has too many petals that it passes on to its offspring. I have only a few seedlings that out of hundreds of seedlings would be saved. The rest ball in the first rain.
Johannes, go easy on john Davis, Dr. Svejda used JD to create Lambert Closse.
I’ve also used it to create some yellows. So far my seedlings haven’t shown any breakdown to black spot, but I haven’t tested them outside my area.
Now most of the Morden roses are off my list.
Hi Chuck, I will show you pictures where John Davis is already heavily infected with blackspot. It is the same as about Adelaide Hoodless. The strain of SP may be local; Terry R has the same difficulties. I suspect the source is Rosa aciccularis, certain years the species will completely defoliate.
Terry, what is your opinion?
'It’s one of my favourite staminate parents. It can contribute outstanding form to the flowers of its progeny and the shrubs can be disease resistant. But much more work has to be done with it to fully understand its strengths and weaknesses in breeding programs.
Photo is a ‘Morden Centennial’ x ‘John Davis’ selection
This is a Op seedling of John Davis. Not only is it showing black spot resistance equal to it’s parent.
It’s better as a staminate than JD.
This is second year of blooming and I don’t know how fertile it is.
Here in Oregon I had Adelaide Hoodless, which I got from a wholesale nursery. It had quite a bit of black spot. I also had Morden’s Fire Glow, which had a lot of black spot. However, they still might be valuable for further crossing. Don’t two minuses make a plus in Algebra? Some of the Buck roses had rust, and I was told that might be coming from roses that had R. Laxa in their background. My growing area is 100 miles from the coast and separated from the sea breeze by a mountain range, if that makes any difference in black spot or mildew. Fragrant Keepsake, yellow HT, was one of the most troublesome roses I have ever had, but it was also one of the most beautiful. It was always defoliated by mid-summer from leaf drop and black spot. I couldn’t stand the sight of it and took it out.
A old-time rambler called Dorothy Perkins lost its vigor and got disease, but it was replaced by a new rose called Super Dorothy HELdor (Wichurana). Does anyone have any new reports on Super Dorothy? It’s from Germany, Hetzel.
I had a very beautiful white Buck rose called Prairie Star that had clusters of very double HT-like blooms. Overall it was pretty healthy, but when the blooms were bursting out they got covered with something like a thin skin of milk-like disease on the blooms only.
Another beautiful rose that had lots of disease problems was Zephirine Drouhin, Bizol 1868, from France.
There is always further crossing to enhance disease resistance. Lady Hillingdon, T, yb, 1910 Lowe and Shawyer, was very beautiful in my yard, but it had persistent mildew and black spot as it got older. I crossed it with Lilian Austin and have registered a rose called Apricot Hillingdon, Jelinek, and it is vigorous and pretty free of disease. Maybe we should keep these disease-prone roses in a gene bank somewhere for further crossing, but not get rid of them altogether. We can probably have a lot of fun with these old roses until the day that the big nurseries develop gene splicing and move the production of roses out of the hybridizers’ realm. That day is probably here already.
Thanks everyone for this thread! It is good to be warned about various roses. John Davis has broken down here, I believe with cercospora. Likewise William Baffin. I have long since banned the Mordens.
This year I have banned Rosa foliolosa.
It’s the latest species to bloom, when I actually have time to pollinate, and I was enamored with its ferny foliage. Plus it is deliciously accepting of modern pollens. Also it has the strange tendency of giving a tiny percentage of fully remontant seedlings when crossed with moderns.
However, my fields are filling up with ferny, leggy foliolosa seedlings with papery single blossoms without many obvious merits. Pierre’s warnings in an earlier thread spring to mind. I won’t rule out revisiting it in the future but this year I have vowed zero foliolosa pollinations.
I’m also done with Alika, Suzanne and Red Dawn X Suzanne. Blackspot.
Pictured is R. carolina x John Davis, since we’re on the topic. This one has not yet broken down, so I’m using it for the chance to make use of John Davis’s combination of hardiness and rebloom.
I’m assuming you’re asking that question because ‘John Davis’ is a triploid. I haven’t had the ploidy of any of my two ‘Morden Centennial’ x ‘John Davis’ selections tested, but for what it’s worth I think of them as being tetraploids.
By the way, these two selections grow in central Saskatchewan and came through the winter very poorly, apparently because of the absence of snow cover. And yet ‘Pink Masquerade’, for example, which theoretically should be much less cold hardy and growing in the same location, did very well with minimal winter kill. I wouldn’t have believed it had I not seen it for myself.
Hi Paul, do you have a microscope that has a grid or a camera? If not I could measure pollen size for you. I have lost the skill that David Z of counting chromosomes.
If you are conserned about me stealing your progeny, just send numbered samples.
I assume that you were in Sask when I sent the Rosa multiflora arrived in Ontario. The multiflora is particularly hardy here that I have. Stunning in bloom. It crosses with Cassiorhodon reluctantly but I have seeds from one complex hybrid (rugosa/blanda cross).
I did stop using ‘John Davis’ due to severe cercospora leaf spot. Though, this thread has me rethinking such, as disease resistance in resulting seedlings runs the gamut from near totally defoliation to others being very healthy and spotless. At times, I’ve even had some rather good results when crossing ‘JD’ with roses with a known poor health record, it’s just a genetic roll of the dice!
Below is an open pollinated ‘John Davis’ seedling with severe infection and a ‘JD’ x hybrid tea that is without a single spot.
Thank you for sharing the contrasting photos of John Davis. I had thought of using John Davis to give winter hardiness, but was given pause by all the reports of it having black spot.
Would crossing John Davis with Morden’s Fireglow, another northern hardy rose, be a good idea?
I have Darlows’ Enigma here in Oregon, which is nearly thornless, continuous blooming, disease free, and hardy to Zone 4. Can anyone comment on the winter hardiness of Darlow’s Enigma? I can’t test it here unless I planted it in the mountains or in Eastern Oregon where it is really cold. I have heard that Darlow’s Enigma was being used in Hulthemia crosses to get the splotch.
Does anyone have any comments from their experience with the hardiness and disease resistance of Pink Grootendorst, HRg, mp, 1923? It has fimbricated carnation-style petal edges.
I don’t have a microscope, so thanks for the offer. Margit is also likely willing to do chromosome examination for me.
I don’t know if my two ‘Morden Centennial’ x ‘John Davis’ selections will flower this year. They grow at the Coutts’ in Saskatchewan, so I’ll check with them. I keep doing this cross, since it produces very attractive flowers. However, repeat bloom may be lacking (it is in the first one I developed).
I’m not worried about anyone stealing pollen of any of my rose selections. If a breeder can use it to develop better roses, so much the better. It’s possible I would get a return in roses they develop that I can use in my breeding programs. If so, I’ll thank them for saving me time and energy in doing it.
Crossing ‘Morden Fireglow’, since it is very prone to blackspot, with any rose would be a bad idea.
The Grootendorst roses are reasonably cold hardy in a Zone 3 climate, although they can winter kill somewhat sometimes. They are generally disease resistant. I’ve seen them do well in this respect on the Canadian West Coast.
I submitted this one for commercial introduction. They were supposed to plant some of the supplied plants, to start cuttings and also use budwood on understock. After not hearing for a long time, I followed up and was told that all the plants supplied, the cuttings, and the budded plants died the first year. I wonder if they were sprayed and died from the spraying.
JohnJel, I have never grown ‘Morden Fireglow’ and seldom have come across plantings, though as Paul has mentioned and as stated upon HMF, it is prone to black spot. On the other hand, I have retained several vigorous plants with a decent good health record from ‘Winnipeg Parks’ x 'John Davis. ‘Winnipeg Parks’ has performed poorly for others, though has been easy and reliable for myself.
‘Adelaide Hoodless’ was one of the very first roses I had grown way back in my youth and the first to exit the garden due to near total black spot defoliation. ‘Hope for Humanity’ has given rise to some of the worst looking seedlings I have ever produced,
The modern Roses were developed here in Manitoba and the only one I’m still using a little is Moderm Blush.
If you wanted to inject some cold hardiness in to your rose, you may look at Frontenac, it was used to create some very
good yellow roses:- Campfire and Never Alone.
Do rose seedlings sometimes outgrow or develop resistance to black spot?
I have a few 2014 seedlings that in 2015 came down with black spot. This year some are showing very little
sign of the disease.