If the farming industry pays at least the lawful Minimum Wage, they should have little problem getting vegetable pickers. The work is healthy out in the sun and fresh air, and a lot better working conditions than some of the jobs I've done in the past.
The job market law of supply and demand may require above Minimum Wages in some areas. But that's only fair. The main reason why farming concerns love illegals is because they are willing to work for less than the Minimum Wage. A competitive wage is what's needed to weed out the loafers not willing to put in an honest day's work.