I don't believe for one minute his lack of being able to pick profitably blueberries by mechanical device. That is if he had the foresight to plant compatable varieties.
Mr Dobbins check here:
http://www.bei-inc.com/
And if manual labor is his choice and Americans aren't available, I don't believe for one minute he couldn't get legal H2A workers. I do believe they'd be more expensive.
I've posted a couple articles like this. If there's a shortage of illegals developing, that's a good thing. That it caught employers by surprise is their problem.