Nothing against what was said above, if you want that much genetic variation in your population. But there are already 4 mostly zygotic mandarin x Ponciris hybrids in use. US 1279, 1281 and 1282 are more than 95% zygotic, and 852 is about 85% zygotic. And Kumin has some F2 citranges that have survived 4 (or is it 5 now?)zone 6 winters. And he has collected some citrimelos and such to bring into his population. I think he is closer to success and will have an easier time than is being talked of here.
I am trying about the same way but I'm way behind him, in spite of his sharing his stock with me. We are both in zone 6, but our climate and soil are different, and our time and space are different.
Also I am also working toward a hardy finger lime. I didn't know that Australian citrus don't cross well with Ponciris. However, at least one finger lime x Ponciris exists in Florida. They aren't sharing it. At least not with me.
I hope my saying this keeps others from trying to breed hardier citrus, and trying different methods, and working toward different goal. I have been in touch with someone in Tennessee zone 7, working on hardier kumquats via kumquat x Ponciris. I think he will be successful in a few generations.
I wish success to all of us. And have fun!
These are very good points. In hindsight, my post was probably too pessimistic/daunting. I certainly would never want to drive someone away from citrus breeding.
The two issues I see with those USDA rootstocks are the limited genetics and the even more limited availability. All three of them are derived from the same Poncirus parent and mostly the same mandarin parent as well, and to date, I haven't seen anyone actually offer them, at least to use plebs. I do plan to ask Stan McKenzie about them when I get around to visiting his nursery (had planned the trip on two occasions this summer, but scuttled those plans were, twice...).
US852, and the child seedling the name of which is escaping me at the moment, that I believe kumin also has, do seem like good options, though the same mild criticism still applies, limited genetics and even more limited availability.
Working with the more distant citruses, like the Aussie ones and kumquats, seems to me like it would be a bit riskier, since the wide genetic crosses could lead to trouble down the road (correct me if I'm wrong, but isn't Thomasville basically sterile, only able to clone itself? I feel like that kind of dead-end will turn up more often for those wide crosses). Not saying people shouldn't be doing it, not at all, I hope people are doing it, and I hope they succeed. I just strikes me as a riskier path.
