The Wheatland Hop Riot

(Wikipedia) The Wheatland Hop Riot, an important and highly-publicized event in California labor history, was the second major labor dispute in the United States supposedly initiated by the Industrial Workers of the World. A bloody clash occurred at the Durst Ranch in Wheatland, California on August 3, 1913, climaxing growing tensions brought about by the difficult conditions farm laborers at the ranch endured.
... Durst advertised for 3000 hop pickers and other seasonal agricultural workers, though he only needed half that number -- in order to drive wages down. Of a $1.50/ day wage, $0.78 - $1.00 was withheld from the workers' pay. If a worker didn't stay till the end of the season, Durst kept that withheld money. Durst then had the workers harassed, cheated, and abused to try to make them leave before the end of the season. Continued

Photo: Child farm worker, Maryland 1909 (more info here).