I ran a simple search in the U.S. Major Dailies database for california AND farmwork to see what kinds of newspaper articles I might find.
Although not solely about farmwork, my search led me to doing some reading about the 1986 Amnesty. This 1987 New York Times article, "Tense Times for Aliens as U.S. Clamps Down," provides some brief background about the law and the second phase of implementation, which relates to employers being fined for hiring undocumented immigrants.
Notice that the use of the word "alien" is less common today. For contrast, here is a 2017 New York Times article, "Feud Over ICE Squeezes Employers in California."
