There are multiple ways around this. As Ken said, if there are crabapples nearby, they will provide the pollen. I have a single Asian pear tree (Shinko). It is advertised as partially self fertile, and many people believe that the ubiquitous ornamental pears will pollenize Asian pears. There are several ornamental pears in my neighborhood, and my Shinko tree sets a lot of fruit, and they have to be thinned. Many fruit catalogs sell multi grafted fruit trees. That is, one tree that has 3 or 4 varieties grafted on as the main scaffold branches. Multi grafted Asian pears and apples are among them. Try Raintree and One Green World on line. If you can't find the apple variety you want as part of a multi graft, and you are not getting fruit set from nearby crabapples, you can graft a branch of another variety yourself. Same goes for the Asian pears. Another option is to plant two apple trees (or Asian pear trees) very close together. This is often described as planting two trees in one hole, but in reality they are a foot or two apart. You can see a description here: http://www.davewilson.com/homegrown/hiDensity_simple.html and here: http://www.davewilson.com/homegrown/BOCpix/4in1hole.html Alex

Ehh it sounds like I might be better off doing a high density, 2 trees in one hole kind of deal. My yard is getting pretty limited on horizontal ground space though, been looking into the tall narrow central-leader apple tree thing (as seen on another thread I made recently). I'm not huge on apples, but the new bare roots were blooming at the nursery and very attractive, thus the urge to impulse buy was strong haha. I might just put in another pluot or something else in to simplify things. Whatever I plant is going to be right on the outer edge of a large bushy tangerine tree. Maybe an apricot to go with my new flavor delight.

As of right now, I have 5 different varieties on that tree. It's a 5 in 1, each variety being single except for the peach, of which there are 2 varieties on the tree. This is the third year in the ground and each graft has at least one fruit on it. The apricot and santa rosa plum have about 5 and 10 fruit respectively, after thinning. I also have a multi graft pluot 3 in 1, with 2 of those varieties being absolutely loaded with fruit even after thinning twice. I purchased a 4 in 1 apricot/aprium for my Mom and it formed up perfectly, with each graft growing about the same. Lots of fruit on it now. For my dad, I purchased a peach/nectarine 4 in 1. This one we had trouble with because I wasn't around to prune. We planted with the thinnest graft facing southwest, but the next thinnest faced the back and it is being shaded out by other grafts on each side. Those grafts have grown so aggressively that they have almost overtaken the 2 smaller grafts. I haven't been up to check in about a year so I don't know how it's doing over all.

I haven't experienced this but this site may help. http://homeguides.sfgate.com/blueberries-yellow-leaves-red-spots-42898.html