Your oberservations about the polarberry are similar to those of some people from a german forum. Some posters wrote that their polarberry’s didn’t set any fruit at all and they were wondering if the plant is even self fertile.
In that case, getting pollen from the polar and polinating the fallgold would probably be more likely then.
Which species is it? Rubus allegheniensis? On a diploid level blackberries often aren’t very self fertile.
According to literature blackberry x raspberry on a diploid level is especially difficult to achieve. I’ve read about unconfirmed hybrids but there are serious incompatibility issues with this cross.
Even rubus ulmifolius x rubus allegheniensis which are both blackberries are hard to combine.
There is however a hybrid of r. ulmifolius and red raspberry that is tetraploid and fertile. The name eludes me at the moment… wyeberry or something. Usually a doubling of chromosomes is necessary in order for these hybrids to work.
Google Nessberry to get an idea.
Found it. It’s called Veitchberry.
http://bulbnrose.x10.mx/Roses/Hurst/CraneVersatility1949/CraneVersatility1949.html
Thanks for the link.
According to google searches it should be Rubus allegheniensis.
I think I found a diploid hybrid. The link is behind a paywall, but the first page is visible.
It seems Burbank created one, a cross between crystal white blackberry x shaffer raspberry.
But the article also mentioned that most seedlings of the cross were partly or wholly sterile.
And from what I’ve read of burbank’s methods he probably made a few hundred plants for testing.
Are there any native tetraploid yellow raspberries, or can chromosomes be only doubled artifically e.g by colchicine ?
I did a bit of a search and it seems there are indeed tetraploid cultivars, but I assume they are red and possibly pretty rare Plant Breeding Reviews, Volume 32: Raspberry Breeding and Genetics - Google Books
I have seeds of a cross sprouting now .Blackberry seed parent needs a pollinator so probably self incompatible . Only thing that blooms at the same time is raspberry . Should be interesting .
Colchicine is long ago outdated. Oryzalin:3,5-dinitro-N4N4-dipropylsulfanilamide and a couple others replaced it due to among other factors significantly lower toxcity to mammals (aka human breeders).
Tetraploid Raspberries are documented and perhaps notable is parent of ‘Tayberry’ a Loganberry type.
Haven’t seen any reference to a natural 4N yellow yet.
Anyone have definitive info on concentration and duration of modern polidy treatments on common raspberries and blackberries?
Good luck! Raspberry x blackberry always has good promise…smaller seeds and faster ripening than blacks and potentialy sweeter than raspberries.
Check out this link for various ploidies of Rubus:
https://npgsweb.ars-grin.gov/gringlobal/descriptordetail?id=85050
Here’s another link with ploidy results (some overlap with the previous link, but this second list does appear to have some not on the other list).
https://npgsweb.ars-grin.gov/gringlobal/descriptordetail?id=85049
Yellow raspberry (most if not all 2x) with 2x white blackberry in my non-expert opinion has promise.
My white blacks are prolific but small fruit and very low druplet count on many.
Each druplet of a rubus is pollinated seperately so every seed can have a different father.
Likely to get much fertile, as for tasty YMMV. Best of luck winning the berry lottery!
If I could heart this comment twice, I would. Words cannot express how valuable this information is to me, it couldn’t have come at a better time!
I’m getting serious again about re-trying my experiments, and am currently acquiring a lot of plants needed for it. As previously stated, I had planned on keeping it all at the diploid level… if I had failed, I would’ve been at a loss. With how easily the diploid raspberries cross (even with “raspberries” from different Rubus subgenera), it would’ve never occurred to me that there could be incompatibility issues when crossing at the diploid level.
My solution to Burbanks sterile Strawspberries was to use a diploid F. vesca instead of the octaploid strawberry. Now that I know incompatibility might become an issue, I have backup plans. If diploid Fragaria x Rubus doesn’t work for me, I’ll try some different combos: F. moschata (6x) X R. idaeus (2x) should produce a potentially viable & fruitful 4x plant. “Prime Ark Freedom” (4x?) X “Fern” Strawberry (8x) should bear a 6x hybrid. Tayberry (6x) X Musk Strawberry (6x) might also work.
For the experiments, I currently have on hand: Rubus allegheniensis “Snowbank” (2x), R. fruticosus PAF (4x?), R. x loganobaccus “Tayberry” (6x), R. ursinus “Wild Treasure” (???x), Fragaria vesca (2x), F. moschata “Capron” & “Male” (6x), F. x ananassa “Fern” (8x), Fragaria x Comarum “Frel” & “Rosalyne” (10x), Rosa rugosa “Jubilee” (2x), Ro. roxburghii (2x), Ro. pomifera (4x).
I’m waiting in the mail for several Raspberry cultivars (“Caroline”, “Jewel”; 2x), a few more Strawberry cultivars of varying ploidy, and the diploid blackberries R. ulmifolius “Burbank Thornless” and R. argutus “Hillquist”. I really wanted to crossbreed BT, Hillquist and Snowbank to make a hybrid diploid Blackberry with thornlessness and primocane-fruiting, but from your comment it seems I’ll have my work cut out for me. I also really wanted to try a diploid counterpart to the loganberry… I have three different diploid blackberries to chose from, maybe one of them will cross with raspberries more readily? I’m not looking to re-make the Veitchberry… I’ll settle for a higher ploidy hybrid, but I’ll consider the experiment particularly successful if I manage a fruitful, productive hybrid that maintains the diploid number (I wouldn’t know where to test it, though).
I’m curious what a Rose x Bramble / Rose x Strawberry hybrid fruit might look like. The Strawspberry seems to take after the Bramble parent more (though both parents are just variations of the same basic fruit structure), but Rose hips look like they have a very different structure, despite being closely related (and with the same monoploid number of 7). If successful… I’d also be concerned that a hybrid fruit would inherit the rose hip’s irritating hairs.
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Incidentally, I found a useful video on cross-pollinating roses and I’m gonna use it as a reference for my experiments (with earlier emasculation, to prevent selfing). The most relevant portion of the video is from 2:26 to 8:09.
Does anyone know by chance a european source for a snowbank blackberry ? I searched back and forth in multiple languages for websites in europe, but since I found nothing at all I assume that no one has it.
I’ve heard cloudberry has been hybridized with blackberry…no idea of the characteristics though.
That’s interesting; I have some red raspberries that include arcticus in their lineage (Anelma, Heisa, Heija). The goal was to get that nagoonberry flavor in a cane fruit, but they still taste like raspberries (but sweeter and less acid). Crossing with salmonberries might be a better bet.
I have been discussing with for example @BerryAllen that it would be interesting to try to use for example Heisa as a mother plant. It has been back-crossed once to raspberry so it is probably about 75% raspberry and 25% arctic. It would have been nice to get hold of a selfed variant of the original F1 (like Merva) where you would have approximately 50/50 arctic and raspberry.
For the original Finnish F1 (Merva) and a similar one described by Gunny Larsson in Sweden in the 60s, both were having raspberry as maternal plant. There are some mentions in the breeding articles that pollination of the arctics with raspberry did not work.
My hope now is that my salmonberry pollination of arctics (where I have a few drupelets) will work. If some of the attractive traits (higher growth, easier detached fruit, self fertility) are co-dominant, I hope to use the resulting F1 as pollen donor to back-cross again against arctic to ensure a pure arctic flavor.
Do you have a source for Joan J. being a tetraploid? I couldn’t find it in my searches.
Also, does anyone know the ploidy level for Wild Treasure Blackberry? I wouldn’t know what to breed it with otherwise.
Might you have a spare sucker or tip-root of Sterling Black? Actively growing? 
I’ve had consistent failure in trying to grow bare root Rubus, but live growing plants adapt well for me. I’ve ordered Tayberry twice, the bare root never sprouted, but the live plant is growing well already.
Also, does anyone have R. armeniacus Himalayan Giant? Or at least fresh seed from a pure armeniacus? And R. laciniatus Oregon Thornless?
Did you ever get those Arctics? If so, how’re they growing for you? I was interested in adding them to my breeding program, but between their preferred climate and photoperiod needs, I figured it’d be quite the long shot for me.
Would a diploid Rubus and a Hexaploid F. moschata work? I figure the moschata might lack the chromosome issues of F. x ananassa (though it might not pair well with the raspberry chromosomes, leading to odd-numbered 1-3 haploid chromosome clusters).
Is that a reproductive barrier for diploid blackberries in general, or is it specific to R. ulmifolius? From what I’ve read, many of the improved American diploid blackberries (pure subg. Rubus, no Idaeobatus involved) seem to possess some level of hybrid heritage, usually involving R. argutus and allegheniensis, among other American species. If they cross well enough with each other, maybe ulmifolius is the oddball?
That’s bound to complicate my project even further. And despite my desire to keep careful track of my project’s ploidies, I’ve no way of testing my plants to verify the levels.
Well I sent cuttings to about 5 people this spring. I kept a couple but only one rooted. Seems you can root from cuttings, but I can do a tip root and have it in the fall. I can send in the fall or hold till spring. The rooted cutting, got mixed up on me, so not sure what it is?
Alright then! Please root one aside for me, and lemme know before the cool temps slow its growth.
It’s 10× according to the ploidy study done by the USDA.