I would suggest advertising some fruit-picking jobs at a guaranteed $50/hour to test your theory that Americans don't want them at any pay rate.
My guess is that the migrant worker proportion of retail cost is <10%. Quadrupling their income would increase retail cost by 30%.
edit:
> What would happen to consumer food costs if farm wages rose and the extra costs were passed on to consumers? The average earnings of field workers were $9.78 an hour in 2008, according to a U.S. Department of Agriculture survey of farm employers, and a 40 percent increase would raise them to $13.69 an hour. If this wage increase were passed on to consumers, the 10 cent farm labor cost of a $1 pound of apples would rise to 14 cents, and the retail price would only rise to $1.04.
Many farm-products have negligible farm-labour cost in their production: beans, rice, tomatoes, pulses, potatoes, onions, grains...
Their farm costs are in land, storage, drying and expensive equipment. They're not being picked by hand and manually weeded.
And even then, the price difference between the farm-gate and grocery store is massive.
Fruit and fresh vegetables are much more labor intense.
You could quintuple the pay of fruit pickers and your grocery bill would go up maybe 50%? Less?