The Department of Labor estimates that of the country's 2.5 million farm workers, most of whom are Hispanic, 52 percent are undocumented. The UFW believes the figure is actually 80 to 90 percent, making the industry a prime target for enforcement. Deportation is relatively inconsequential for some harvesters in Yuma, since many are seasonal workers who commute daily from Mexico, where they board buses just north of the border for a 20-minute ride to the fields. But many of the year-round migrants who follow the crops from Salinas to Yuma and back again—and who account for up to 40 percent of Arizona lettuce harvesters—live full-time in the U.S., and for them, to risk deportation is to risk estrangement from established communities and families.

If workers are reluctant to return to Arizona, growers may find themselves short on harvesters, in which case "the crops rot in the field," says Wendy Fink-Weber, director of communications for the Western Growers Association, which represents 90 percent of fruit and vegetable growers in Arizona and California. Greens, which are a finicky crop and demand near-perfect conditions, have only about a five-day harvest window after reaching maturity. Each head of lettuce is cut and packed into boxes by hand. The intensive labor associated with growing lettuce—a $1 billion business for Arizona and the state's highest-value crop—accounts for up to 50 percent of the cost of production.

A main alternative to relying on migrant laborers is hiring workers registered under the temporary agricultural worker visa, H2A. But growers say this is undesirable, and Fink-Weber describes the initiative as a "very inflexible, onerous, expensive guest worker program." Brian Church, director of operations at major grower-shipper Church Brothers, thinks mechanization could also offer a quick solution if workers disappear, although he notes that "you have to sort with the eye and the hand. No machine can find defects like the human eye."

The experience of Colorado, which enacted restrictive immigration legislation in 2006, suggests another alternative. Workers fled the state, and farms, desperate for labor, partnered with the Department of Corrections to pilot an inmate-harvester program. Tom Church, the president of Church Brothers, says the absolute last resort is finding Americans to work the fields. "If we had to rely on American workers, it would never get done," he says. According to Brian Church, the company would sooner resort to machines than H2A or inmate labor.

Farm managers are reluctant to predict precisely what will happen when they return to Yuma, especially as municipalities across Arizona are questioning their ability to implement and enforce the new law, which may well be overturned before lettuce transition season. But the worst case scenario is a crop that is left to rot, meaning incalculable financial losses for farmers—and expensive salad while Arizona's supply goes to the worms.

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