Rather than eliminating farm workers, then, technology enabled agribusiness to restructure and discipline a newly expanded work force. According to Ernesto Galarza, automation enabled the deskilling and downgrading of certain tasks as when, for example packing operations were "moved from town sheds to movable assemblies on wheels," and the jobs were reclassified as unskilled fieldwork, while women were substituted for men and paid less. Mechanization further enabled the expanded exploitation of low-wage, non-citizen Mexican guest workers who were particularly subject to subordination within the machinery of production. Recalling McWilliams’s prediction that mechanization would spark renewed labor organizing, a post-war boom period in the technological development of productive forces in agribusiness coincided with a series of farm worker union actions in the San Joaquin Valley between 1947 and 1952. And as the history of the Bracero program suggests, rather than eliminating the contradiction between capital and labor, the use of technology often helped to reproduce and expand it.