Brainstorming some crosses: hardy, yellow, reblooming

Roses for Hybridizing Cold Hardy Roses
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I just wrote the following in a letter to a friend…I thought why not share it since the forum has been quiet lately. I know we all like to dream! Pardon the rambling. (When I talk about Rrrr and such, I’m talking about R being the dominant gene for non-remontancy, and the little ‘r’ being recessive remontancy genes. Supposedly you need four little r’s to have a reblooming tetraploid.)

I’ve been brainstorming a lot about crosses for next year.

Yellowness. Hardiness. Remontancy.

I’ve been thinking about David Z’s call for us to use more Persian Yellow. I think I have a small one started in the gardens but I don’t remember seeing blossoms on it yet. If it does I will certainly try to use it. Ideas:

R. xanthina x PY
Brite Eyes x PY - hopefully enough latent hardiness in Brite Eyes or High Voltage to result in an F1 that is able to bloom in my climate.
High Voltage x PY
Darlow’s Enigma x PY
Belle Poitevine x PY - go ahead and try to double the chromosomes straight off? Ending up with a fertile hexaploid?
Rugosa #3 x PY
Prairie Peace x PY - I like this idea…PY in it’s lineage maybe makes the cross more likely to take. Will have to extract embryos.
Ross Rambler x PY - trifluralin?

Trying for remontant yellows, the best I can do is:

Rugosa #3 (easy hip setter, many seeds, has been shown to pass on juvenile bloom) x R. xanthina - try to get enough seeds to make trifluralin treatment an option. Hope for fertile, blooming, tetraploid, yellow offspring of which I could plant mass quantities of OP seed in hopes of recovering remontancy.

As an aside. In regards to trying to get remontancy out of a RRrr tetraploid such as the result of the doubled cross above. Instead of just going for the 2.8% of F2’s that might be rrrr, maybe it would pay to plant about 10-20 F2’s, let them mature, and then test OP F3 populations to see which of the F2’s might be Rrrr, which should be about 1 in 5. Once we’ve identified the Rrrr plants by noticing rebloomers among their offspring, really hit them hard: pollinate them amongst themselves, plant all OP seed, and use them with tender yellows like High Voltage. The goal: a cane hardy, remontant, tetraploid yellow!

Also R#3 and Belle Poitevine could be pollinated with Hazeldean. Likely the resultant seedlings would be triploids, and maybe sterile. I have 314 seeds from Belle Poitevine x Hazeldean this year…maybe I will try treating some with trifluralin.

I have soooo many OP Rugosa #3 seeds this year that I think I will try treating some of them, too. My dream of a fully remontant, fully hardy tetraploid of any color is so tantalizing.

My R. xanthina showed 100% hip set this year (1 for 1). So there is another path, perhaps. Use hardy, remontant diploid pollen on R. xanthina. I have ordered some 2-3’ bare root, and I expect at least some of them to bloom this year. I’ll plant them somewhat late to delay the bloom so I have pollen available. Pollen parent ideas: Henry Hudson, Belle Poitevine, Rugosa #3, Ross Rambler, Darlow’s Enigma, Grouse. (The last two are questionable if the offspring would end up hardy enough to bloom here).

Then do I attempt to chromosome double the seedlings? I think I’d like to try, for two reasons: First, these wide crosses might result in sterile diploid offspring. Second, eventually getting a fully remontant tetraploid will give more genetic firepower when crossing with the likes of R. carolina and R. virginiana. The path of crossing those tetraploid species with a diploid rebloomer and trying to recover rebloom is just too long, I’m thinking.

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Joe keep brainstorming as long as you like, especially when it comes to [color=#FFFF00]yellows[/color], my favourite color. You won’t get any negatives from me.

Regards David.

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Did any of the Chinese Xanthina germinate for you, Joe? I planted half mine (no sprouts) last January and the other half yesterday.

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I ended up with five seedlings of those R. xanthina, Kim. Abuse and abandonment seems to be the key. They were seeded in a small open pac such as in which we sell bedding plant six-pacs. They didn’t germinate with the rest of the roses, so I just let the pac sit around ignored, getting completely dry on several occasions. The five germinations were spread out over the summer.

Nat just sent me a bunch more seed, plus I ordered some 2-3’ plants from Lawyer Nursery, so I’ll have xanthina in my panthina next year. Lawyer claims in their description that they have sought out a northern seed source for increased hardiness. It will be interesting to see if there is variation between Nat’s seed and Lawyer’s plants, and how much variation there might be within the plants from each source. I also got one from High Country this spring.

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Joe,
For me, the three crosses that make the most sense would be Brite Eyes x PY, High Voltage x PY and Rugosa #3 x PY. These offspring will probably be tetraploid, be snowline hardy (hardier with R#3 x PY) and have two copies of the repeat bloom allele. Have you thought about using PY with any of the Explorer series or Parkland series roses? I know the Parklands are fairly BS prone also but I think you like Prairie Joy. How about Prairie Joy x PY?

Do you have Goldbusch or Julie’s EGS1 (Easy Going x Suzanne)? Both of these are snowline hardy here and bloom quite readily. The BE x PY and HV x PY crosses above could have offspring that would be similar to EGS1. Goldbusch repeats well and is a good seed parent. I have numerous seedlings from it. This year I did a GB x Sparkle & Shine cross. I even have several GB x EGS1 second year seedlings that were as hardy as both the parents last winter. One has the blooms of EGS1 but was a shy bloomer last year and the other bloomed much more but the flowers were a light pink. I’m not sure if either will have repeat bloom yet but if they don’t there is an 80% chance they will have 3 copies of the repeat bloom allele. If so, then the offspring with a cross with a repeat blooming plant should have a 50% chance of repeat bloom.

This is my experience with chromosome doubling. Back in 2007 David gave me a Rugosa that he had doubling the chromosomes on and it worked on two of the three layers of cells. Most importantly it worked on the layer that produced the flowers and gametes. It wasn’t a very strong grower and I culled it after 3 or 4 years. But I was able to collect some OP seeds from it and raise some seedlings. Some of the seedlings turned out to be sterile and I culled them. Two showed promise and a measurement of the pollen grain of one of them (B0104) indicated that it was a tetraploid. I tried numerous crosses with it and grew OP seedlings of it. But the measurement of the pollen of all of the seedlings from it so far have turned out to be diploid. I measured the pollen of B0104 again and this time there was a mix of diploid and tetraploid size grains and I’m not sure why that is. It’s sibling, B0101 is a not as strong of a grower and produces fewer flowers. But it’s pollen has more grains in the tetraploid size and it’s seeds are twice as large as B0104s seeds. I have only grown OP seeds of B0101 and haven’t done any crosses with it but I may have better luck getting tetraploid offspring from it than from B0104.

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Hi Paul,

Thanks for the response. I could definitely tack Prairie Joy x PY onto the list. Maybe Frontenac or Felix LeClerc. I’m fed up with the Parkland series. If you can tolerate them I should give you a copy of my Yellow Winnipeg Parks. It’s an OP seedling of Winnipeg Parks that turned out to be light yellow. A good bloomer. I assume it will have the same disease issues, but it appears to have better vigor than Winnipeg Parks. Good seed setter. Hey, I guess I should try that one x PY, too.

I’m going on the assumption that Rugosa #3 is diploid or has reverted to diploid. I think David Z mentioned having tested it. However, it’s still very fertile, appears to be self-sterile, and gives seedlings that bloom young.

I don’t have Goldbusch but I have EGS1. EGS1 would definitely give hardy-enough-to-bloom seedlings when crossed with Persian Yellow, and it would be very fun to see the results. Good idea.

Interesting to hear about your doubled rugosas. I think we should keep trying to get a hardy, reblooming, tetraploid rugosa. I wonder if it has to be selfed for a few generations like you’re doing, to iron out the kinks.

Ross Rambler seemed to have true repeat here last year. I wonder if that could be crossed with any of the reblooming rugosas. Has anybody here worked with Ross Rambler?

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I understand about the Parklands, I’ve pretty much given up on them except for Prairie Joy and Prairie Celebration, neither of which I’ve done any crosses with. I love Frontenac because I’ve gotten quite a few very worthwhile seedlings from it. It passes on good disease resistance, repeat bloom and hardiness. But only as the pollen parent because it doesn’t set many hips and I only got 1 seedling from the OP seeds I tried germinating.

I don’t know how well a cross of EGS1 x PY or vise versa would be because neither are a good seed setter. And while most of the offspring would be hardier than PY, about 67% would have only 1 repeat bloom allele and 17% wouldn’t have any. Only 17% will get both repeat bloom alleles from EGS1.

I suspect that part of the reason I got so many diploid seedlings from the Rugosa B0104 is because there were a number of diploid rugosas nearby to pollinate it. I was hoping the OP seeds were selfed because I figured there would be a good chance of getting tetraploid offspring then. I have a number of B0104 x Frontenac seedlings and surprisingly the only one to bloom so far was a diploid, not what I was expecting.

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Joe, you might want to read the article called “Mislabeling and the Birth of a Legend” in the Spring 2012 issue of the RHA Newsletter. The Ross Rambler is a seedling of Rosa laxa, Retzius. Like many once-bloomers, it may repeat after dormancy-inducing conditions, but true recurrence is not likely. Percy Wright propagated a fall-blooming laxa (as he called it), but it did not repeat bloom for Griffith Buck. With this as with many things, the three important things are location, location, and location. The species itself is once-blooming except under abnormal circumstances.
Peter

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What was reportedly Ross Rambler was sent to me years ago. I had it in the Newhall garden and it was remontant in that mid desert climate. It had two full flushes of bloom, spring and late summer into fall, in the years I grew it there. What I had fit the two photos on of Ross Rambler on HMF.

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Kim,

It’s not uncommon for the Ross to do this. When I grew the Ross in Lubbock, TX back in the 1980s, it always had a fair number of early fall flowers, but never as many in the fall as in the spring and early summer. By the fall, the hips from the early summer blooms were ripening or ripe, so the plant had red hips and white flowers at the same time. And that is the way it behaves in Morden, MB. The article in the Spring 2012 issue of RHA Newsletter has as one illustration a closeup of Ross Rambler taken in August 2009 by Leo McAdams at Morden Station. This picture shows ripe hips with new flowers–very attractive. And in an area where truly recurrent, tender roses may bloom only twice because the season is so short, this form of blooming must seem almost the same as true recurrence. But when I look at these plants I see that the new flowers are emerging from the same canes as the earlier flowers. In some cases, that means they are coming directly from old wood, and in others it means that they’re emerging late from a cluster which grew directly from old wood. I have seen this on some seedlings from Ross, and on seedlings from R. laxa Retz. Although the flower is there–some will say that this meets the criterion for “remontant”–for me the important fact is that the flower is not coming from the most recent flush of current-season growth.

Some of the Explorers exhibit the same kind of reblooming. For instance, when growing vigorously John Cabot will send up new basals, or other major canes originating from old wood, in mid summer or even late summer. It will even have a few flowers coming late to the party from earlier clusters. For more than 15 years I grew Wm Baffin (cutting from Henry Kuska). It was reported to be recurrent, but it never repeated for me until the fungi here figured out how to attack it. Once its leaves became susceptible to fungi here, a sort-of-rebloom began: the plant would be defoliated by mid summer, and then it would put out new growth from the previous years’ canes, and those new canes would have terminal clusters. But there never was any truly recurrent flowering.

For practical purposes (if flowers are practical), a once-bloomer is fine in a place where the season is short. Many shrubs commonly planted as part of the traditional foundation plantings (“green mustache”) on houses bloom only once for a few days per year. Joe Bergeson has mentioned spirea as an example of these shrubs which are not expected to rebloom. This year Rosa bracteata had some flowers here from mid June until the end of September, with the main display from mid June until early July. But does this mean that bracteata is recurrent? Not as I see it. The late flowers were parts of old clusters, were on the tips of canes that grew longer than usual and so did not develop buds until the cane had reached its final length, or were directly on growth which emerged late from old wood.

For us hybridizers, maybe the important question is whether these tendencies to repeat (for whatever reason) can contribute to the development of roses that are truly recurrent in cold zones. Griffith Buck successfully incorporated much of the cold-hardiness of R. laxa, Retz. into his recurrent lines, and Henry Marshall incorporated R. arkansana’s repeat tendencies into his lines, and incorporated some of Buck’s work (Prairie Princess is a very important parent in the Parkland roses) into his truly recurrent lines. Getting the recurrence cost some hardiness, but creating these roses that are reliably crown-hardy (many are also cane-hardy) in USDA zones 3 and 4 is a considerable accomplishment.

Can we do the same with other somewhat-remontant species (getting truly recurrent blooming from R. bracteata and other relatively tender species, gaining whatever disease and pest resistance they have and adding hardiness–and maybe decreasing the size and aggressiveness of the nasty prickles)? A good question, and a real challenge. Several of us are playing with bracteata and clinophylla derivatives. Maybe our children will see the results. The recent recurrent Hulthemia hybrids show that these things can be done. Modern hybridization with R. hulthemia was begun in the 1960s, and only about 50 years later we are seeing some very attractive and reliably recurrent hybrids.

Peter

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Thanks, Peter. Merry Christmas! I think I received Ross Rambler from you. I enjoyed it as it was a beautiful, healthy rose. Thank you!