CARNEROS, Calif. » The growing appetite for truffles is feeding demand for dogs trained to sniff out the pungent fungus prized by chefs and foodies.

As more landowners plant orchards in hopes of harvesting truffles, more dogs are being trained to detect the earthy delicacies, which take several years to ripen on tree roots underground.

"There is huge demand for truffle dogs right now," said Alana McGee, co-founder of the Truffle Dog Company, which helps orchard owners search for truffles and trains dogs how to find them in orchards or in the wild.

"Truffle-hunting is right up their alley. It’s fun for the dogs. They get rewarded for using their noses, which is how they see the world," she said.

On a recent morning, McGee’s dog Lolo, a brown and white Lagotto Romagnolo, sniffed for signs of Perigord and burgundy truffles on the roots of oak and hazelnut trees planted next to Robert Sinskey’s vineyards in Carneros, Calif.

Sinskey was the first Napa Valley winemaker to plant a truffle orchard five years ago and wants to be the first California grower to harvest truffles, hopefully next year. He plans to have McGee teach his dogs the art of truffle-hunting.

"I hope my dogs will finally be able to earn their keep," Sinskey said. "It will be nice to see them actually work."

Lolo is an Italian breed commonly used to hunt truffles, but McGee said any dog can be trained. "It’s about working with the dogs’ personalities and different learning styles."

In Europe, truffle hunters traditionally used pigs, but in recent years the job has gone to the dogs, which are easier to manage, less conspicuous and less likely to eat the tasty tubers or bite a hand trying to snatch one from its mouth.

Known as the diamonds of the culinary world, most black truffles come from Europe or Australia and cost $800 to $1,200 per pound, but supplies are shrinking while appetites are expanding worldwide, said Robert Chang, chief truffle officer of the American Truffle Company.

"As people get richer all the time, the demand for truffles will continue to grow," Chang said. "Ten years ago, you mention the word truffles, and people think, ‘Oh, it’s the chocolate truffles.’"

European black truffles, the ones most coveted for their powerful taste and aroma, are notoriously fickle. Few in North America have successfully harvested them, but many are trying because the crop could be highly profitable.

The American Truffle Company is working with dozens of landowners across the U.S. to grow European black truffles commercially. It’s still too early to judge their success since the orchards were planted less than five years ago, and it takes at least that long for truffles to ripen.

But in March, Chang’s colleague, Paul Thomas, said he harvested Britain’s first cultivated black truffle from fungus he planted in Leicestershire six years ago, using the same techniques their company is using in the U.S. and other countries.

In California’s wine-growing regions of Napa and Sonoma valleys, the American Truffle Company is working with several winemakers, including Sinskey, Rocca Family Vineyards, former Intel Corp. CEO Paul Otellini and most recently Peju Province Winery.

The trees don’t require much water, so they haven’t been affected by California’s record drought, which has forced farmers to tear out orchards and reduce crop plantings.

Napa Valley Chef Ken Frank, widely regarded as America’s top truffle chef, imports the delectable fungus from Italy, France and Australia. He loves the idea of serving fresh, locally grown truffles at his restaurant La Toque.

"To be able to get a truffle that was dug in Carneros this morning for me to put on the menu tonight, that’s a game changer," Frank said. "That’s a big deal and we’re very excited about it."