SACRAMENTO, Calif. (Reuters) - California would become the first U.S. state to require farmers to pay overtime to field workers and fruit pickers under a bill approved by the legislature on Monday and sent to Democratic Governor Jerry Brown for his approval.

The bill, which passed on a mostly party-line vote, would phase in overtime pay for farmworkers from 2019 to 2022. Small farms that employ 25 or fewer workers would have an additional three years to phase in the pay.

If signed into law by Brown, California, the largest U.S. agricultural producer, would the first state in the country to require farmers to pay overtime to laborers who work more than eight hours a day or 40 hours a week. The governor has not said if he will sign the measure.

The bill is the culmination of decades of lobbying and pressure by the United Farmworkers Union.

The Democratic-controlled legislature rejected a version of the same bill earlier this year, but supporters amended it to phase in the overtime rules more slowly.

Opponents said that requiring farmers to pay overtime could damage the state’s agricultural economy, where workers toil up to 60 hours a week during the harvest season but can go for months without pay other times of the year.

They predicted that farmers would be forced to cut workers’ hours to just 40 hours a week to avoid having to pay time-and-a-half or double-time overtime.

Supporters, mostly Democrats, said the issue was one of fairness to farmworkers, who are among the few U.S. hourly workers not paid overtime.

“For me, it is a vote about my conscience,” said Democratic Assemblyman Eduardo Garcia. “We will be improving the lives of people.”

(Reporting by Sharon Bernstein; Editing by Bill Rigby and Peter Cooney)