Named varieties of food apples are all clones. As with all clones their viability goes down with each generation. Crab apples are closer to the wild species, and therefore have higher fecundity, which allows them to pollinate the rest of the orchard. Around here the apple growers all have at least one crab apple amoungst their trees.
richard valley wrote:Like to hear more about carbapple and food apple. I thought pollination had to be with the correct apple tree.
The cedar waxwings absolutely tore through my neighbor's remaining crab apples (two trees worth) and then ate most of mine (four trees worth) in early November, 2011. IF for no other reason than that, it was worth it to have the big flocks visit for a few days. Nice to be able to provide for such beautiful birds. They did leave a heck of a mess but shoveling snow a couple of times has removed all the "residue".
I have two very old apples trees (variety unknown) but don't worry at all about pollination due to the pollen provided by crabapples.
One, the native-type crabapples, or similar hybridized ornamental varieties, which are really cool and pretty trees, great for the birds, but generally only insignificantly edible, e.g you could eat them, but you may burn more calories picking out the seeds than you would gain by eating. The fruit of this type are generally garbanzo-sized or usually smaller
Two, the crabapples with larger fruit, e.g dolgo is a common one with fruit around the size of gumballs. Kids love to nibble them, and they make great jelly/jam/cider. There are also bigger varieties of crabapple, here in the south we have one called craven, that has apples almost as big as a small apple. The jelly/preserves are a delicacy around here, comparable to quince preserves. The trick with crabapples and hard cider too, is that if you naturally ferment the cider, you get something called a malo-lactic fermentation going on. Essentially, you get an apple juice that is barely drinkable it is so sour, but it finishes to a slightly tart dry type cider. Very yummy. Actually most seedling apples are a bit crabby from my experience, and in a historical sense were used for alcohol production.
The only crab apples I've ever eaten were growing in my grandpa's yard. They were small, green, and sour as heck! I'm 95% sure they were Malus coronaria, the so-called "sweet" crab apple, which is native to Michigan. I've never had any jam, cider, or butter made with crab apples so I can't comment on their use for that. When Pehr Kalm, one of Linnaeus' twelve "apostles" encountered Malus coronaria, he suggested that they were useless for making anything but vinegar. If you're interested in making your own vinegar, I think crab apples would be a good candidate so you don't have to waste your better-tasting fruits on that service.
However, I've read that most crab apple species taste fine after they've been baked or roasted, so it's completely possible that they could be as legitimate a food source as the domestic apple.
Most apples will do fine with any pollinator EXCEPT apples that are too closely related (for instance Golden Delicious and Red Delicious do not pollinate each other well because they are both sports of the Delicious apple. They also do not pollinate well with the Gala apple, of which they are close parent-lines of). Only a handful of regular apples are self-pollinating, and I only know of one fully self-pollinating apple. I do not know how crabapples rate at self-pollination.
Apples do not come true from seed, though certain characteristic are more likely to show up if the parent tree had them in seedlings. This is why apples are 'cloned' by grafting scion wood into a different rootstock. Apples with excellent flavor tend to not be as hardy as, say, cider apples, so that is why they are grafted onto hardy rootstock and you will rarely, if ever, find rooted cuttings or own-root regular apples, unless you grow one from seed. All commercially sold apples and even heirloom varieties are propagated this way. Apples and crabapples are not seperate species (for instance, the Granny Smith apple is a chance seedling of a crabapple orchard.)
Crabapples are also sometimes grown as a food source for wild creatures, such as birds and foxes.
Only a handful of regular apples are self-pollinating
About a year ago I started a thread about self-pollinating apple species. I have listed about 5 dozen varieties.
They are also quite nice to look at in the spring
They're also very good for bramble jelly. Use a 1:6 proportion of crab apples to blackberries, plus the rind and juice of a lemon for every 1Lb of crabapples. You make it in exactly the same way as crab apple jelly. Ditto hedgerow jelly (blackberries & sloes).
If you can be bothered with the fiddle of peeling, coring and chopping them, they're also good for chutneys. I usually use bramleys instead though, since they're easier.
When the crabapple blossoms the blackfish start biting, so the folklore goes. Other than that it just made a mess and attracted yellow jackets.
We eventually replaced it with a calendar.