I live adjacent to an apple orchard and get wood from there all the time. I get mine from the piles of trimmings and/or storm damage. I never gave pesticides a lot of thought, but I'd agree that if they didn't degrade over time, they wouldn't have to spray regularly to reapply it.
I also agree that most fruitwoods these days come from some large orchard. Noone raises fruit trees for the wood!
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