By Ben Worthen On 3,000 acres in the Lodi area, the Cortopassi family is pioneering a new olive planting-and-harvesting technique that could one day make California a presence in the world olive-oil scene. For 24 hours a day over the next three weeks, modified grape harvesters will drive two miles per hour through rows of tightly packed olive trees, shaking loose the fruit. The olives will be delivered to a nearby mill and pressed into oil without ever being touched by human hands. Using this "super-high-density" technique, the Cortopassi family of San Joaquin County, which also grows cherries, apples, walnuts and other crops, will grow about 700 olive trees per acre, or more than two million trees in all. That's about 15 times the per-acre density used in a traditional olive farm."We wanted to do olive oil but hadn't figured out a way to make it a viable agricultural business," said Brady Whitlow, president of the family's Corto Olive brand, which planted its first olive trees in 2004. "Super-high density was the key." Until recently, California's olive farmers—concentrated in the northern part of the state around the Bay Area—were mainly small producers, deploying hands-on planting and harvesting techniques similar to those that Greeks and Italians used centuries ago. But the new super-high-density approach, which was developed in Spain more than a decade ago, has now led to the creation of industrial-scale olive farms. That has allowed the amount of olive oil produced by California growers to jump to 1.2 million gallons in the 2010 harvest from 383,000 gallons in the 2004 harvest, according to the California Olive Oil Council, a trade group. The council estimates California will produce six million gallons of oil in 2015, based on the number of trees now in the ground. Overall, the U.S. imports about 75 million gallons of olive oil each year.But while large and small olive growers say they are optimistic the super-high-density approach will drive a California olive-oil boom, the new method also is likely to reshape the local industry into two tiers: one that's a large-scale agribusiness that sells bottles for $10 or less, and another made up of boutique producers that sells smaller bottles for twice the price. Even with premium pricing, small producers may have a hard time of it. "They don't have the economies of scale," said Dan Flynn, executive director of the Olive Center at the University of California in Davis, noting that boutique growers aren't using their land as efficiently as the super-density farms. Handpicking olives is also expensive, amounting to half the cost of production in some cases, he said. Still, Kathleen Elliot is among the artisan olive growers counting on a rising tide to lift all ships. She's been making oil from 137 olive trees planted across five acres on a ridge in Sunol since 2004. She sells it in 200-milliliter and 500-milliliter bottles at 17 area specialty food stores for $10 and $25. For now it's a part-time business. The 2010 harvest produced 350 gallons of oil that she's still selling. And her costs are high, including $450 a ton to mill her olives—last year she had 15 tons—and about $4,000 for a crew to pick. Ms. Elliot plans to grow olives full time starting in a couple of years, but she currently also works at a flower nursery and teaches agriculture classes. Super-high-density will help drive awareness of olive oil generally, she predicts. When that happens and when consumers understand the different flavors that different olive varieties produce—similar to the way many wine buyers can distinguish between a pinot noir and a cabernet—they'll flock to boutique oil producers like her Hillcrest Ranch, Ms. Elliot said. "People here are foodies," she said.Super-high-density planting came to the U.S. about a decade ago, when California Olive Ranch in Oroville launched an olive-oil business based on the technique. Others, such as Coldani Olive Ranch, soon adopted it as well. Currently, only three olive varieties will tolerate super-high-density planting. But growers are experimenting with other varieties and hope to develop more.Corto, meanwhile, didn't try olive growing for years because the Cortopassi family felt the practice wasn't economically feasible. In 2004, after super-high-density began to be adopted, Corto changed its mind. The company ripped out acres of grapevines to plant super-high-density olives. Its 500-milliliter bottles of oil retail for $5.99 to $6.99, although it primarily sells them restaurants. Mr. Whitlow said the price is low to attract customers who haven't tried California olive oil before. "With the super-high-density we can compete on price," he said. Write to Ben Worthen at ben.worthen@wsj.com ...