WASHINGTON — On more than 10,000 acres of drained swampland in western New York, Maureen Torrey’s family farm grows an assortment of vegetables in the dark, nutrient-rich soil known as “Elba muck.” Like other farms in the area, Torrey Farms of Elba, N.Y., depends on seasonal labor, mainly undocumented field hands from Mexico, to pick, package and ship its cabbage, cucumbers, squash, green beans and onions throughout the nation.

With the peak harvest season at hand, Torrey’s concerns about a labor shortage are growing. A crackdown on illegal immigration, more job opportunities in Mexico and rising fees charged by smugglers are reducing the number of workers who cross the U.S. border illegally each year to help make up more than 60 percent of U.S. farmworkers.

The American Farm Bureau Federation projects $5 billion to $9 billion in annual produce-industry losses because of the labor shortages, which have become commonplace for farmers such as Torrey, who said there were 10 applicants for every job five years ago.

“In the last year that wasn’t the case,” she said. “We hired anybody that showed up for field work. It’ll be interesting to see how many people we have knocking on the door this year.”

With the cherry harvest under way in south-central Washington state, the Sage Bluff farmworker housing compound in Malaga is only half full, with nowhere near the 270 workers it can accommodate.

“I would say we’re significantly short,” said Jesse Lane, the housing manager for the Washington Growers League, which runs Sage Bluff. “I had a grower contact me who said he only had 20 pickers and he needed over a hundred.”

In California, farmers are reporting labor shortages of 30 percent to 40 percent, said Bryan Little, the director of labor affairs for the California Farm Bureau Federation. He said some cherry growers had left acres unpicked because they didn’t have enough workers.

“Generally, what I hear is that if you need 10 crews to harvest 40 acres of strawberries, you only have seven,” he said. “If you need a crew of 10 people, then you only have six or seven. It varies, depending on where you are in the state.”

The problem is particularly tough for small farms that need crews for only a few days. Sixty percent of hired farm labor works on farms with annual sales of less than $1 million, but most field pickers would rather work for weeks or months at a time on larger farms, said Manuel Cunha, president of the Nisei Farmers League in Fresno, Calif. “They’re not going to leave their full-time growers to work for a day or two on the small farms, so a lot of fruit isn’t getting picked,” Cunha said.

Border patrol agents no longer pose the biggest risk for Mexican workers who cross the border illegally, Cunha said. Drug cartels and human traffickers now prey on illegal immigrants, forcing them to transport drugs and kidnapping their relatives to make sure they comply.

To avoid them, many undocumented workers simply stay in America after the harvest season. “Workers won’t go home, and the workers that do go home will not come back because they’re afraid,” Cunha said.

Because labor makes up nearly half the production cost for fruit and 35 percent for vegetables, farmers who face labor shortages are switching to crops that require less manpower, such as corn, soybeans, cotton and peanuts.

“You don’t make as much money on them, but you don’t put nearly as much into them and you don’t have the labor costs,” said Frank Gasperini, the executive vice president of the National Council of Agricultural Employers.

Torrey’s farm has followed the trend. She grows field corn, which is used for grain, on 3,500 acres today, up from 2,000 acres 10 years ago. Labor accounts for only 5 percent of corn’s production cost.

“It’s pretty common around here,” she said. “I’m talking like in a four-county area going 70 miles each way, you don’t see new packing sheds. You see shiny new grain bins.”