At Chandler Farms, in the San Joaquin Valley just outside of Selma, Calif., about three dozen workers are needed each season to pick acres of delicate peaches, plums, nectarines and citrus.

In recent years, however, owners Carol and Bill Chandler have struggled to find laborers as immigration from Mexico has slowed to a near-standstill.

"When the crops are ripe, we need a reliable labor force," she said. "That's what we're worried about going forward."

The Chandlers are among farmers who welcomed a move last week by Congress to make immigration reform a legislative priority this year.

But the promised changes may not be enough to solve their chronic labor problems, which have been exacerbated by deportations and a stronger Mexican economy.

Last week, a group of Republican and Democratic senators unveiled a blueprint that aims to grant legal status to an estimated 11 million illegal immigrants in the country.

President Obama also joined the fray, urging Congress to move legislation along quickly this year.

Immigration reform has been a rallying cry among farm groups for years. Farmers have long reported chronic labor shortages that predate the recession. During the housing boom, for instance, contractors persuaded farm workers to leave the fields and work in construction.

According to the U.S. Department of Agriculture, half of all hired crop farm workers are in the country illegally. Of all workers, 7 of 10 are from Mexico, a country that has provided a steady supply of farm laborers since the middle of the 20th century.

With immigration reform back on the table this year, farm groups are fiercely lobbying to make sure proposed legislation includes provisions for their workers.

Previous false starts

There have been false starts in the past, including efforts by former President George W. Bush, who sought to create a guest worker program and overhaul immigration laws during his administration.

But the latest push to tackle the highly politicized issue is "one of the best signs we've seen in a long time," said Ken Barbic, senior director of government affairs for Western Growers in Irvine, Calif., a trade group that represents farmers in California and Arizona.

If Congress passes legislation, "the folks who are currently working here with false documents, it takes them out of the shadows," Barbic said.

Barbic added that immigration reform would remove legal liabilities for employers who hire illegal immigrants.

Some breathing room

Diego Olagaray, 51, who grows 750 acres of wine grapes in Lodi, Calif., said that granting legal status to the state's agricultural workers would mean that both farmhands and employers could breathe a little easier.

"Some of these workers go back to Mexico on a regular basis," Olagaray said. When they travel, "they're fearful of something happening to them. With amnesty, it'll make them feel more comfortable. They'll also feel that they're part of society. And it will make it easier for employers as well."

Olagaray said that if immigration isn't resolved soon, labor shortages will become more pronounced. Last spring, he said he had trouble filling his usual crew to tend his grapevines during growing season, and other growers saw ripe crops languish in the fields.

Still, any policy effort may do little to solve the labor shortage, said Edward Taylor, a professor of agriculture and resource economics at the University of California, Davis.

Such shortages predate the recession. During boom times, contractors persuaded many workers in the fields to work in construction jobs, according to Taylor, who recently co-wrote a study that examined the decline in the number of farm workers from Mexico.

A key finding in Taylor's study was that more immigrants were staying home to work on Mexico's farms. They were taking advantage of a strengthening Mexican economy and a growing middle class.

As a result, American farmers are competing for a dwindling supply of workers.

Paul Wenger, president of the California Farm Bureau Federation, said farmers are well-aware that their industry is changing.

And although he agrees that a dwindling labor supply will cause problems farther down the line, he said Congress should still pass immigration reform that will allow farmers to hire legal farm workers.

"Within the next two decades, we're going to have a problem: A domestic workforce will not want to work in the fields," he said. "It's going to be a problem. But that still doesn't mean we shouldn't fix the problems that exist today."