Long shot here, but does anyone know if they can pollinate each other? They’re my only 2 blooming trees and I’ve been hand pollinating with a paint brush every other day and nothing is setting. They’re about to be 3 years old after planting. Should I be focusing on pollen only from the biggest and healthiest flowers?
My candy heart is in its last 20% bloom and my flavor king is in its first 20%
I just looked this up. Plums do need compatible partners, just like cherries. One option is email Dave Wilson and ask them for the compatibility S alleles for each of these cultivars and make sure they are not identical.
It’s not possible to tell if there’s fruit set until about 2-3 weeks after pollination. If the flowers are falling off now, while tree is still blooming, then sure you can tell. But if as normal the flowers stay attached, it takes some time to know if anything has set.
Flavor King has never set heavily for me. It never takes much thinning even in the best years.
For hand pollination focus on the flowers that are shedding pollen. Go back and forth from tree to tree and hit the flowers that are shedding pollen. Those flowers will also be receptive.
Agree with Steve’s advice the blossoms are usually most receptive to pollination several days after they fully open. You should see the stigma looking wet and sticky. That’s a sign of receptivity.
Dennis
Kent, wa
Here is an interesting quote from an article I found. It suggests you may be on to something (this was in one specific country on a limited number of plums and we would have to find the S alleles of the cultivars you are growing to know whether this applies):
Four alleles, S b, S c, S e and S h are widespread and together are responsible for 87% of the S -haplotypes therefore many of the cultivar combinations are semi-compatible. In Israel semi-compatibility was shown to correlate with low yield.
https://www.sciencedirect.com/science/article/abs/pii/S0304423808001878
More searching reveals less genetic diversity in S RNase alleles in my yard than I realized:
Laroda SbSc
Beauty ScSe
Santa Rosa ScSe
Flavor King SbSe
Flavor Grenade SbSc
From what I have been able to find, 100% of my identifiable allele plums have B, C, or E alleles and are very similar to the problems identified in Israel.
Add scattered Southern California bloom to the mix and I am just glad I get fruit set at all! Of course, I have other plums whose S alleles I can not find which hopefully are more diverse.
From what I have read in UC book on plums and peaches. If J.Plum is self-fertile it can pollinate other plums/pluots. However, factors influencing pollination are bloom overlap, pollen quality, and climate. Wickson and Santa Rosa are preferred pollinators recommended to be planted in commercial orchards.
Does the pollen of the tree have to be other one of the genes from the pistil or can it be totally different allele specific to that tree?
The S alleles are an anti-inbreeding mechanism. So you would want different alleles (1 of the 2 minimum, must be different). The point of the article was that we seem to have inadvertently, over the last century since Burbank, concentrated our plum genetics into only a few incompatibility alleles. This may explain problems like what you are facing, and probably also limits production in my own yard.
These sorts of issues were worked out for cherry long before the genetics were understood. But they seem to be less widely known and understood for plum.
That is true for cherries, self-fertile pollen will not get rejected in the pollen tubes. That would be a nice shortcut for plums if it can be confirmed. If so, SouthTX could try Inca plum for an early pollen source… update: I found an article that suggested that paradigm may not fit, unfortunately.
A few hours of reading has really validated some of the challenges with plums and interspecific:
-They need pollinizers of course
-But the genetic diversity for the compatibility factors (S alleles, RNase enzymes that chew up and arrest pollen activity in the pollen tubes) is concentrated among 4 alleles in over 80% of cultivars
-I also learned that plums have a lower germinability rate of pollen in general (46% cited by Janick and Moore textbook on fruit breeding)
-And that pluots are probably even lower (same text, cited 12% for interspecifics from an earlier era)
https://www.sciencedirect.com/science/article/abs/pii/S0304423815302612
Most of the CH flowers aren’t staying attached except for 4 flowers where the petals have come off and I have a small green bulb. But, each of those bulbs fell out after about a week.
FK flowers aren’t either but it’s super early in its bloom.
I’ll try to look for more receptive flowers! Thanks for that tip
In your example, does that mean Flavor King pollen is either Sb or Se? Or can it have a totally different allele?
Also, are all Flavor Kings SbSe?
here is a post with excerpts from the book describing nuances of J.Plum pollination.
Flavor King and Sweet Treat Pluerry should pollinate each other. Same should be true for Candy heart.
It’s me then 
Hi,
Answer is Yes,
Alleles:
Flavor King SbSe
Sweet Treat SeSa (Sa as Salpha, new allele)
Candy Heart ScSh
Be careful with the information about pollinators in general in internet, in this case DWN is right, but not in all cases DWN is right.
If you want to add more varieties, just do it , but not thinking in improving FK pollination, just add high quality varieties, not add SR because in general is well know to be a good pollinator, there are other better quality varieties with the same good pollinator level or enough for your orchard varieties.
And my recommendation will be to let nature do its job.
Best Regards
Nice work finding that FrankG. Where did you find those allele groups? I could not locate those online and I would love to look up the other pluots.
A and H are relatively less common which means Sweet Treat and Candy Heart are quite likely to be pollinized by whatever other plum a person has blooming at the same time in their yard.
SouthTX, younger plum trees tend to dump their flowers to save energy. If you can get your trees to full size and healthy, and TX weather cooperates, sounds like you are set up for success.
Awesome info, Frank!
Where did you find this information, so I can look up other plums? Also, do you remember DWN saying some pluots don’t pollinate other pluots? I don’t own any other pluots, but I’m wondering if it’s because they ended up with the same S alleles.
@JamesN Great read!
https://www.tandfonline.com/doi/pdf/10.1080/14620316.2012.11512900
I found Methley is SbSg, and (not sure if I’m correct) but the Methley pollen by passes the self incompatibility. So, Sb pollen can pollinate Sb flower. Interesting!!
I have read here members suspecting if Flavor Grenade is self-fertile due its ample fruit set compared to other pluots. Do you have any thoughts to support or dismiss this behavior of FG.