Regardless, nostrademons' point still stands. Over 50% of US farm workers are undocumented immigrants[1], and 1 in 10 farm workers in California are undocumented migrant workers[2]. That's a very sizable chunk of the labor pool.

[1] http://articles.extension.org/pages/9960/migrant-farm-worker...

[2] http://www.npr.org/sections/thesalt/2016/01/29/464758284/act...