My Fuji's on M26 bore the year after planting and every year since. They are about 8ft tall and 8ft across. The fruit is not all that big and I thin a lot. So I don't think you are asking for anything unusual.

The rootstock has more effect on tree size and age of bearing than most other things. Get one on a dwarf or semi dwarf.

The Fruitnut

Kayan:

Fuji is a wonderful apple, and widely available on the full range of rootstocks, from standard to full dwarfing. But Fuji is not the only good apple around, and you may benefit your cousin by expanding your search criteria.

There are several apple varieties technically classified as "crabs" that are medium-small apples and very tasty indeed. The expert around here on these "lunchbox" or "pocket" apples is Lucky, who may provide his opinion if he notices your post, but a couple of the best varieties are Callaway and Chestnut. There are several others whose names momentarily escape me. With a little looking, you should be able to find these varieties on rootstocks such as M-26, or the semi-dwarf M-7, which might also fill the bill.

As for maintenance, while there are a few newer apple varieties that advertise resistance to certain apple diseases, keeping an apple tree and its fruit disease and insect free depends more on the prevalence of diseases and insects in your area than on the variety of the tree. It would be nice to be "fully organic", and not to have to spray at all, but most of us have to if we want our trees to prosper and produce edible fruit. It isn't much fun for a child to pick an apple off the tree and find the core full of black frass and a couple of codling moth larvae. If the children begin to associate apples with worminess, there goes all the fun. And you can grow healthy, non-toxic apples with some early chemical sprays, as I do here every year.

Don Yellman, Great Falls, VA

My fuji is only 6 feet tall on M7 and makes small fruit because I don't thin. Another good seet kid apple is gala; small fruit and very sweet.

Thanks, Don.
I think the edible crabs are a great possibility for kayan's cousin's project. She'll probably need some guidance from zone 9 growers, though.
My top pick would be Centennial(DolgoXWealthy) a nice mid-sized apple crab - the essential lunchbox apple - has a nice balance of sweet & tart. I know it performs in zone 8 - would probably work fine in z9. I have one on M26(I think), that's been in the ground for 12+ years now, and is still less than 8 ft tall.
Callaway was a favorite for my kids - they liked the flavor, and could stuff their pockets full of the little 1-1.5" fruits. It is classified as an ornamental crab, but fruit quality, even if small, is good - and it's a heavy producer - often assumes a weeping character, just due to fruit load, with good disease resistance(it was selected at Callaway Gardens, in GA, where it's hot & humid).
I like Kerr(DolgoXHaralson), but it's more tart than its half-sib Centennial, and has a musky/wine undertone that kids might not appreciate.
Chestnut and Wickson crabs constantly get good reviews for flavor in taste tests - but I'm still waiting for mine to fruit; have never personally tasted either.
I don't have a Trailman crab, but I've seen good reports on it from northern growers - and photos of the fruit look very much like Centennial.

Thanks to everyone who has responded! The crabs seem like a good choice. As a matter of fact, they sound so good I'm interested in getting one for myself! I'll be visiting my cousin sometime this week and taking a look at lighting, soil, etc and I'm glad I have something to work with. :)

Kayan,
I have a semi-dwarf "Pixie Crunch" that would be great for kids. Here are the reasons I like this tree so much...
1. Bears fruit quickly (2-3 years)
2. Small size tree so care is very easy
3. Great taste and color. The fruit is very crisp and sweet and juicy. It just tastes great. The color is a beautiful blend of green and red.
4. Small "kid size" apples (about 2-3" diameter)
5. Fruit ripens early, about mid to late August (great for impatient kids :-)
6. Also it is a good tree for "bagging" since the stems are long and skinny.
7. Heavy producer.

This is my favorite tree. It is producing tons of great apples and I've only had it a few years.

Where are you located? You are getting recommendations from southern growers in humid, hot conditions. If you are west you won't have nearly so much disease and insect pressure.

I never saw a crab apple when I was a kid and I wouldn't assume that the kids will love their small size- kids often don't want to eat what they are not used to. Actually I never saw a kid turn away a fruit because it was too big- if anything large size is an attraction. They do seem attracted to bright red (I think that unfortunate tendency is hard-wired in our DNA).

I get a good chance to see what kids are attracted to at an annual picking party one of my clients has at his orchard (I make my living installing and caring for small orchards). About a hundred kids come every year. Ideally, they generally like a tree they can climb in, but I realize you can't wait that long.

If you are planting one apple, I would choose one that stores well and also can be used for baking if Mom or Dad likes making pies, crisps and other treats. Teaching kids to enjoy desert built around fruit can lead to a lifetime healthy association.

But if small and quick to yeald are absolutely essential I guess storage won't matter much. I'd take the kids to a local grower and let them choose the apple they'd like best. That way, they'd be invested in the project and learn more.

Wickson Crab has excellent quality in our dry heat, low-chill area (seems to have excellent quality wherever its grown). It started bearing quickly and is reliable every year; pretty reddish/yellow apple too; reminds me of a "Big Stick" popsicle bar.

Applenut