I'm in upstate NY near the Canadian border, and we have literally hundreds of dairy farms and orchard fields. The kids work on them, mostly rural who are used to farm work anyway, but it's getting done without illegal Mexican labor.
What I'd like to see is more of an attempt to mechanize farms as much as possible, Studies have shown that could cut down on as much as 35-50% of the intense labor needed on farms. I'd be willing to pay taxes to help farmers in that respect, it's cheaper than subsidizing millions of illegals and their endless social needs.
Agree with you that mechanization would help, however if we dried up the source of undocumented cheap labor, don't you think the farms would mechanize on their own? Same is true for all successful business, if a commodity is inexpensive (be it energy, labor water etc) there's no economic advantage to using it efficiently. When the supply is reduced that's when you see efficiency come into play. Look at the auto industry , when gas was cheap you had the gas guzzler cars, in the 70s with the oil shortages, we first saw economy cars.
In the case of labor, as long as we have people willing to work in slave like conditions (because anything in the U.S. is better than the turd-world) you have business all to happy to employ people with low wages & no benefits. Problem is, these corporations have money and can buy politicians who will keep the supply of cheap , slave-like labor flowing into the country.