I've been told this works for veggie gardening - not sure if it's transferable to fruit trees, but its worth a shot. Basically, take used dryer sheets, dump a tablespoon or two of cayenne pepper in the middle of it, and tie it shut with a piece of twine (so you get a ball of cayenne pepper). Make up a bunch of them, and hang them at various places on the tree, preferably around the fruit. You can try the same thing with moth balls too. Again... not sure if this will work for trees, but I've heard of people having success in their veggie gardens with this method. I've also heard of people making a hot pepper spray, and lightly spraying down their fruit trees (not sure if this will have any adverse effects on your tree). I personally think your best option is to try putting some sort of flange or baffle around the trunk of the trees to prevent squirrels from climbing up them. Or... as a last resort, perhaps a BB gun or some motion activated sprinklers? Hope this helps! Hang in there!