The president’s son Eric Trump in the vineyard at Trump Winery on July 20, 2011. It has sought 29 temporary immigrant workers since December 2016 to help prune its vineyards. (Jack Looney)

The vineyards and fields of Virginia are busy in spring, as farmworkers prepare the seeds, soil and seedlings for the growing season ahead. About 3,300 of those laborers are foreign seasonal workers, who arrived on a temporary visa with the bureaucratic name of H-2A.

The number of H-2A visas granted nationally has doubled in the past five years as farmers have sought reliable labor for jobs that they say are shunned by Americans. Farmers complain that the program is expensive, cumbersome and essential to their enterprises.

But the visa program’s future is unclear as the Trump administration considers how to reform national immigration policies.

One factor in its favor: The Trump Winery in Charlottesville has sought 29 temporary immigrant workers since December to help prune its vineyards. When news of the applications first broke, the outrage expressed by those who remembered the president’s pledge to “hire American” was predictable.

But the winery, whose manager did not respond to requests for comment, was just doing what thousands of other agricultural enterprises have done: using a well-established 31-year-old visa system to find people willing to do the grueling work necessary to plant, grow and harvest crops.

“I don’t know what we’d do without it,” said Linda Clark, general manager of the Grace Estate Winery in Crozet, Va., which employs five H-2A visa workers this season, four of whom have come from Mexico every year for the past five years. The Americans she has hired over the years leave after a week or a month, and in the past two or three years, no American has applied for the jobs she has, she said. “I want the public to know these workers are not taking Americans’ jobs.”

Other winemakers agree.

“We are proud that 85 percent of our team members are from Virginia,” Dave Kostelnick of Early Mountain Vineyard in Charlottesville, said in an email. “The other 15 percent are seasonal workers, most of whom have been with us for multiple growing seasons, who come through the H-2A visa program.”

“I’ve had good success with it in the last 20 years,” said Sharon Horton of Horton Vineyard in Gordonsville, Va. She and her husband employ 18 H-2A workers on their property, and she said she hopes the visas remain, because if they don’t, “I’m in big trouble.”

President Trump did not suggest changes to the H-2A visas in a draft executive order dealing with foreign worker visas that circulated in late January. His family’s businesses, including the Mar-a-Lago resort, have hired about 500 temporary foreign workers under a similar visa program for nonagricultural temporary foreign workers.

Daniel Costa, director of Immigration Law and Policy Research for the Economic Policy Institute, said he is skeptical that Trump will take any action regarding low-wage worker visas, and might even deregulate them. The administration seems more focused on the high-skilled H-1B visas that bring foreign technology workers into the United States, he said.

It’s not easy to get H-2A visas. Farmers are required to prove that they have repeatedly advertised locally for U.S. workers. There’s a multistep and multiagency process to get certified for the visas before they are issued, and then a farmer’s representative also has to work with the embassy of the country from which the workers come. The U.S. farmer then must provide transportation to and from the United States, as well as local transportation, meals and housing. The jobs usually pay between $10 and $13 per hour.

Last year, some farms had two to four weeks of delays because of a backlog in federal processing of the applications, a delay that can be devastating for time-sensitive farming tasks.

The American Farm Bureau estimates that H2A visas provide about 10 percent of the nation’s farm workforce. It also notes that about 80 percent of farm laborers are foreign-born and about half are undocumented workers, who may be at risk if the Trump administration follows through with its plans to crack down on illegal immigration with a wall along the U.S.-Mexico border.

“In our minds, the best [border] wall is a functional guest worker program,” said Kerry Scott, program manager for Mid Atlantic Solutions, the nation’s largest private provider of H2 workers. “We’re certain our program will be one of those that survives and thrives.”

Although the program has been in place since 1986, it’s not without opposition.

Adrienne DerVartanian, director of immigration and labor rights for the advocacy group Farmworker Justice, said it’s illegal for foreign brokers to require recruitment fees from workers, but the practice persists. Workers are sometimes exploited but are intimidated into keeping quiet when they want to speak out, for fear of losing their jobs, she said.

“We have a lot of concerns because we think this program is fundamentally flawed in ways that harm both farmworkers and Americans,” she said. “If wages and working conditions improved, that would help. But we don’t believe our country should rely on guest worker programs. If workers are needed, they should be able to come into this country as immigrants . . . and become citizens through the normal process.”