Rat deterent?

I'm next to a field and the little rat critters always eat half the fruit or more every year. Too many in the field for traps or poison to have much effect. I read where rodents hear higher frequencies than dogs & cats, and am wondering if a whistle in that range might keep them away without irritating the pets next door?
Or some other way to keep them out of the trees and off the house? Maybe trimming the trees so that the limbs are not touching anything, and wrapping aluminum foil or some other guard around the trunks?
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On Fri, 3 Jul 2015 02:31:09 -0700, "Snuffy \"Hub Cap\" McKinney"

Yes, look here .... http://www.amnet.net.au/~tsbelts/belts/photos/MouseTraps/
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