posted 3 years ago
I feel you might be help to clarify these issues for yourself and get more useful information online and in books if you call pepo, maxima, moschata and mixta "species" rather than "families." The common terminology is that these are all species in the Cucurbita genus, which is in turn in the Cucurbitaceae family, commonly known as the cucurbits. The family includes melons and cukes and several other genuses.
Things in the cucurbit family but not in the same species are unlikely to cross. As Joseph said, even between two species in the genus, crosses are rare, often sterile, and he has mentioned which types of such crosses he has seen work. But crosses within species are common and easy. I've seen Joseph point out that the C. pepo varieties are so different from each other that they are hardly worth crossing (spaghetti squash, acorn, delicata, zucchini, yellow summer, patty pan, and toxic bitter ornamental gourds). Only the acorn and delicata are worth crossing together because they are similar winter squash, and the zucchini and summer squash varieties are similar enough to give a similar summer squash outcome. With C. maxima, the varieties are pretty much all used as winter squash or, in the US, ornamental pumpkins. As long as you are crossing maximas that are used as winter squash, and you want a variety of winter squash that works well in your conditions, then you can cross maximas as much as you like.
Why are you trying to cross between species? What is your goal? For example, I don't understand why you want to cross an acorn (C. pepo species) with a butternut (C. moschata species).
In order to get some landraces that produce well in your conditions, what I've learned (from reading, not personal experience, so I'll be happy to see corrections) is to plant a couple different varieties (of the same species) that do well in the specific conditions or have other desired characteristics (such as flavor, storage, shape, size, resistance to some problem you've got in your area, etc.) and let them cross. If one of them turns out to be great in the first generation, then my choice would be to discard the crossed seeds, and the next year only plant several of the old original seeds, and then keep using their offspring.
I bought C. maxima seeds from Joseph Lofthouse several years ago and have been growing them. Last year I also grew delicatas but they are C. pepo so they won't have crossed. Last year, I also grew some C. maximas that a Japanese friend gave me saying they were from Hokkaido, but I think they are what is generally called kabocha in the US (which turns out to be the generic Japanese word for C. maxima). Anyway, the Lofthouse maximas are great in many ways: flavor, productivity, ability to grow and ripen by direct seeding or transplanting (the transplanted plants get much larger and produce earlier, and about 5 times the weight of squash than the direct seeded plants). Previous years they stored great until March or April. The only drawback is most of them are so huge that we can't use one up before it goes moldy, and there isn't always space in the freezer to keep some for later. The kabocha is much smaller and similarly tasty. So I thought this year I should save seeds from the Lofthouse squash and kabocha that grew next to each other, aiming for an intermediate size. ... but!
But then all the kabocha developed mold in January so I had to use them up hastily. And most of the Lofthouses developed spots that were going to go moldy in Feb so I am using them up hastily. The ones that went off were all from one Lofthouse plant, a very productive transplanted one. So I scrapped that plan. There's one Lofthouse squash left now, of a very different shape. It's still in good condition, though it was one of those direct seeded plants and I wasn't even sure if it was ripe and mature before harvesting it. So now I'm planning to save seeds from it, and in 2022 I will plant some seeds from this one, that may have crossed with the small kabocha. And I'll plant some of the original seeds I got from Joseph too.
So here are the traits I'm hoping to breed for:
Flavor: Both the Lofthouse maximas and the kabochas are excellent.
Storage: This is very important, as my region gets a few months when fresh vegetables are hard to buy, Jan-April.
Size: My ideal size would be intermediate between the kabochas and the Lofthouse maximas. But this trait is less essential than flavor and storage.
There haven't been any problems, pests, or diseases on my squash plants so far, except mild late powdery mildew that hasn't been a problem, so I'm not trying to breed for resistance.
So my question to you is, what are your squash breeding goals?
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.