ESCALON, Calif. — The soaring value of California’s nut crops is attracting a new breed of thieves who have been making off with the pricey commodities by the truckload, recalling images of cattle rustlers of bygone days.

This harvest season in the Central Valley, thieves cut through a fence and hauled off $400,000 in walnuts. Another $100,000 in almonds was stolen by a driver with a fake license. And $100,000 in pistachios was taken by a big rig driver who left a farm without filling out any paperwork.

Investigators suspect low-level organized crime may have a hand in cases, while some pilfered nuts are ending up in Los Angeles for resale at farmers markets or disappearing into the black market.

Domestic demand for specialty foods and an expanding Asian market for them have prompted a nut orchard boom in the state’s agricultural heartland. Such heists have become so common that an industry task force recently formed to devise ways to thwart thieves.

“The Wild West is alive and well in certain aspects,” said Danielle Oliver of the California Farm Bureau. “There’s always someone out there trying to make a quick dollar on somebody else’s hard work.”

Amid the nut boom, farmers have torn out vineyards and other crops to plant nut trees to keep up with demand. Real estate firms, retirement funds and insurance companies have taken note by adding almonds, walnut and pistachio land to diversify their portfolios.

As the nation’s top nut producer, the state grows more almonds and pistachios than any country. Only China produces more walnuts, which have nearly tripled in price in the last five years to about $2 a pound, according to the California Walnut Board.

The U.S. Department of Agriculture reported that through 2012 the state’s almond crop was valued at $5 billion per year, pistachios were over $1 billion and walnuts were over $1.5 billion.

“Right now, everybody wants to be a nut grower because it’s kind of like the gold rush of the 1850s,” said Ripon almond farmer Kevin Fondse of Fondse Brothers Inc. “Everybody wants the gold.”

That frenzy has spawned crime. In a brazen heist in October, thieves made off with 140,000 pounds of processed walnuts from GoldRiver Orchards. The thief cut through wooden fence posts in the dead of night, hooked up a truck to three gondola trailers brimming with nuts and drove off.

In another incident, unemployed trucker Francisco Javier Lopez Martinez told investigators he couldn’t pass up a job paying $180, despite his suspicions. He was hired in October by a man who gave him a fraudulent driver’s license and told him to pick up 43,000 pounds of almonds at Sunnygem, a processing plant.

A transportation broker tipped sheriff’s deputies that something seemed amiss. They arrested Martinez, who told them he was supposed to drive the load to a specified address in Los Angeles, park it and walk away.

The trucking firm that hired him turned out to be a fake. The company’s logo was merely taped onto the side of the truck, and it had stolen license plates. Martinez pleaded guilty in December to commercial burglary and possession of fake identification. He was sentenced to 350 days in jail and three years of probation.

Authorities say this type of industrial identity theft, known as a “fictitious pickup,” is becoming more sophisticated. It often involves con artists providing fabricated insurance documents and U.S. Department of Transportation numbers for trucks.

The driver presents the paperwork to the unsuspecting nut processor.

A walnut farmer suspected he had fallen victim to such a crime in March after a $250,000 load left his yard, so he called detectives Pat McNelis and Matt Calkins at the Butte County sheriff’s department. The detectives traced phone records to Los Angeles, where police there served search warrants and seized evidence. The investigation continues, detectives said.

“In our case, there’s multiple levels of people that were involved in a complex crime,” Calkins said. “This is an organized criminal enterprise. It’s not one or two people acting on their own.”

The California Highway Patrol investigates cargo thefts, but doesn’t tally nut thefts separately. The CHP hasn’t established a link between such thefts and any specific criminal organization, spokeswoman Erin Komatsubara said.

Growers and nut processors say they have been so hard hit in the past year that a coalition formed a task force in October to seek the advice of police and to create an eight-step checklist for growers and nut processors.