Try thinking this through - your plan is one-sided. You have no contigency plan once the immigrant farmworkers are taken out of the picture. Simply eliminating them is the easy step - figuring out a way of replacing them is a whole different set of problems. Simply saying, "Oh, local farmhands will do the job," or "Just pay locals more money," are not realistic solutions, IMO.$9.50/hr for farm labor in Georgia and they cannot understand why people are not rushing for jobs that would put a family of 4 living in Georgia under the poverty level by about $4,000.00 a year.
Naturally tax payers would have to subsidize anybody who works on a farm and has a family. I would rather pay more at the store so that the farm worker does not need to collect entitlements which increase taxes. Of course those who do not pay taxes would rather cheaper food prices.
You need to "touch all the bases."