a triploid malus floribunda is still likely going to be smaller then 2.5". The question you need to ask is what exactly you want to do with the fruit? If you want an very early or very late season pollinator there crabs for that. You want an apple that makes great sauce, crabs for jelly, crabs for pickles, bitter-sweet crabs to balance out your cider recipe, there is a crab for that? I ordered a Pitmaston Pine Apple this year, its a very small apple and has a strong pineapple flavor. If I graft it on to Bud9 that might just shrink it down to crabapple sized.
from what I am have reading I think Geneva Crab is Triploid or Allopolyploids
Allopolyploid infers a plant composed of the full genomes of two related species that usually have different chromosome numbers. A rutabaga is an allopolyploid of a turnip and a cabbage (we’ll argue details later, see triangle of U) that occurred long ago. The resulting plant contains 38 chromosomes which is the full complement of both parents. This differs from a tetraploid which usually results from chromosome duplication in a single species. Okra is an allopolyploid as another example. I have not seen anything published indicating an allopolyploid in apple other than the chromosome doubling event about 65 mya. Do you have documentation showing an example of an apples that is an allopolyploid? https://en.wikipedia.org/wiki/Triangle_of_U | http://www.jamesandthegiantcorn.com/2010/08/31/apple-genome-part-2/
I’m going to also add some information about the reason why a triploid can produce seed but not viable pollen. Meiosis in plants diverges significantly as compared to animals. The short version for pollen is that a pollen grain for most plants contains two duplicate cells each with a single set of chromosomes. When there are three sets of chromosomes, only two sets can pair up to initiate division leaving one set of chromosomes unpaired and therefore unable to duplicate and then split into paired pollen cells. Rare events can cause even a triploid to sometimes produce a small number of viable pollen grains. This is significant for example in potato breeding where triploids can be generated and sometimes be induced to produce just enough pollen to be used in breeding.
For the ovule, the process is dramatically different. I am going on memory with this so please check that it is correct. The primordial female cell initiates a duplication where it doubles the number of chromosomes, then doubles the number of cells, then repeats until there is a cluster of 16 cells in the proto-embryo. Eight of the cells are discarded leaving 8 cells to form the embryo. A single set of chromosomes winds up in the cell that can be fertilized by pollen, two sets wind up in the structure that becomes the endosperm, and 5 cells move into support functions. When the pollen grain moves through the style, it splits in half with one set of chromosomes merging with the single set of chromosomes in the ovule and the other merging with the 2 sets of chromosomes in the proto-endosperm. The result is that most of time the seed contains an embryo with 2 sets of chromosomes and triploid endosperm that has 3 full sets fo chromosomes. The endosperm is discarded when the seed germinates and depletes the stored reserves leaving only the growing plant which is normally disploid. Now ask the question, what happens when the pollen grain is from a tetraploid? The resulting seed has 3 sets of chromosomes in the embryo and 4 sets in the endosperm. Voila, now you have a new triploid apple!
And I understand Hewes Crab is likely an interspecific result (think that’s the term for cross-species progeny) between un-named domestic apple and whatever native crab predominates in Virginia. In the case of Hewes, it is not triploid, but self-fertile or PSF.
There are some other Etter-bred crabs that are less well-known than Wickson but worth trying, such as Crimson Gold, Vixen, Muscat de Venus, Atalanta’s Gold, and Amberoso. All but Crimson Gold are difficult to find except as benchgrafts from Greenmantle Nursery, as they’re trademarked and require non-propagation agreements.
Some other small-to-crab-sized apples that are also worth trying: Chestnut, Trailman, Kerry Pippin, Margil, Wyken Pippin, Yellow Ingestrie, and the aforementioned Pitmaston Pineapple.
I’m growing all of these as either trees or grafts, but so far only a few are old enough to bear yet. (Actually, Yellow Ingestrie has eluded me thus far, but @derekamills will hopefully be able to remedy that next season.)
Thanks, I keep those in mind. I was very close to getting a Wickson crab last year from Cummins, but didn’t. Maybe when my trees get bigger, I might try grafting some crabs onto them.
I didn’t know Pitmaston Pineapple was a crab, I thought it was just another apple. I guess it’s a small apple, not technically a crab like you mentioned.
This looks to be the best place to mention my observation from yesterday: Looking over the Rambour Franc tree - a triploid - there are absolutely no blossoms developing on it this year. Last year it bloomed all over, for the very first flowers seen on it, setting at least 300 fruits. It is 9 x 9 feet, on Geneva30. I thinned the fruits to 90 and found hardly any viable seeds in them at maturity. With so few full seeds, I had no concerns about it going biennial.
Looks like I must thin it drastically next year in order to break the biennial cycle. Maybe leave a dozen on?