FRESNO, Calif. – Farmers in "America's Salad Bowl" are turning into hunters — stalking wild pigs, rabbits and deer — to keep E. coli and other harmful bacteria out of their fields.
It's part of an intense effort to prevent another disaster like the 2006 spinach contamination that killed three people, sickened 200 and cost the industry $80 million in lost sales.
The exact source of the contamination was never discovered, but scientists suspect that cattle, feral pigs, or other wildlife may have spread the E. coli by defecating near crops.
The pressure to safeguard crops comes from the companies that buy fresh greens. In response, some farmers are taking gun-safety classes to learn how to shoot animals that could carry the bacteria. Others are uprooting native trees and plants and erecting fences to make their land inhospitable to wildlife.
Spinach grower Bob Martin has even poisoned ponds with copper sulfate to kill frogs that might get caught in harvesting machinery or carry salmonella on their webbed feet.
Produce buyers "got us by the short hairs," said Martin, one of few growers who would talk publicly about how he is protecting his crop.
But some officials have questioned whether such drastic measures are necessary based on limited evidence.
"We're trying to talk now with the companies, buyers, retailers, wholesalers to bring things back into balance," said Scott Horsfall, executive director of the Leafy Greens Handlers Marketing Board, which oversees new farming standards drawn up after the 2006 E. coli contamination. "There's a real pressure out there on growers that goes beyond what the science justifies."
Concern over contamination is most pronounced in the Salinas River Valley, where valuable farmland and sensitive wildlife have coexisted for centuries. The lush valley, described in John Steinbeck's "East of Eden" and nicknamed "America's Salad Bowl," grows 60 percent of the nation's lettuce.
The nonprofit Resource Conservation District of Monterey County, which works with landowners to sustain wildlife habitat, surveyed 181 leafy greens growers who manage more than 140,000 acres. The survey showed that more than 30,000 acres had been affected by trapping, poisoning, fencing or removal of natural habitat.
The survey also indicated that 32 percent of respondents were convinced by corporate food-safety auditors to remove non-crop vegetation. More than 47 percent had been asked to "remove" wildlife, and 40.7 percent of those surveyed complied.
Growers, packers and shippers adopted new food-safety standards last year for farms, including a requirement that farmers establish 30-foot buffers between their fields and grazing land for cattle, which are known carriers of E. coli.
The standards acknowledged that wildlife could also carry the bacteria, but they had no requirement for buffers between wildlife habitat and fields.
"I think there's a little brinksmanship going on," said Hank Giclas of Western Growers, who was part of the committee who wrote the standards. He worries that processors are exceeding the rules to gain a sales advantage without good science.
Going beyond the guidelines "without going through a review process is something companies have the right to do, but it would be better if they'd go through the program," he said.
Smaller growers argue that stricter guidelines aren't warranted for farmers growing fresh bunched greens. They say the problem is primarily with cut greens that are bagged, which allows bacteria to multiply if temperatures rise.
Industry representatives defend their above-and-beyond restrictions.
Fresh Express, with 41 percent of the bagged greens market, demands a mile between farm fields and feedlots for cattle instead of the agreement's recommended 400 feet. The company also requires that a field intruded on by a wild pig be kept idle for two years.
Barbara Hines, a spokeswoman for Fresh Express, which processes 40 million pounds of salad each month, said the company's tighter regulations are "generally valued" by its retail customers, which include grocers such as Safeway, Vons and Harris-Teeter.
Earthbound Farms also exceeds regulations in many areas, especially in seed and water testing and its one-mile requirement between farms and feedlots. But the company views fencing and removal of natural habitat as a counterintuitive last resort.
Habitat is what animals want. "If you remove it, they will go into the field," said Will Daniels, Earthbound's vice president of quality, food safety and organic integrity.
Fresh Express has funded a $2 million study into methods of potential E. coli transmission. Results are due next month.
The Western Institute for Food Safety and Security is conducting a separate study funded by the federal government. It plans to analyze carcasses and anal swabs from 7,000 birds, wild pigs, cattle and other animals collected by state officials. Hunters are being asked to turn in deer colons for the research.
Officials are also collecting 13,000 soil, water and plant samples in the hope that the study will rule out wildlife as risks and ease buyers' fears.
"We have two extraordinary resources in this area: wildlife and our agricultural community," said Terry Palmassno, a senior wildlife biologist at the California Department of Fish and Game. "It's our position that you don't need to destroy one in order to save the other, and that's what we're working on doing."