I have the same problem with squirrels. Although I haven't tried it on my fruit trees (I have just about given up on them), it seemed to work last year to put 2 shower radios tuned to talk radio in my garden playing 24/7. I put the volume low enough that my neighbors can't hear it and I can just barely hear it from my patio. Seemed to make the squirrels think there were people in the garden and they stayed out. I got 2 cheap radios ($10 each radios like the ones pictured). They sell at bed bath and beyond and also amazon.com. Just remember to check that they are still on and keep plenty of batteries on hand.
Jen
