The nation's largest supermarket chains have given produce growers six weeks to establish new safety rules to prevent E. coli outbreaks.

A consortium that includes owners of the Vons, Albertsons and Ralphs grocery chains and Costco Wholesale Corp. is alarmed that another episode like the recent contamination of fresh spinach could hurt customers and the companies.

"We need a timeline to focus energy on taking action immediately," said Ron Anderson, vice president of produce for Vons owner Safeway Inc. "Obviously there is a sense of urgency in the mind of the consumer."

Nine E. coli outbreaks linked to lettuce or spinach have been traced to California since 1995. The latest one, in September, killed three people, sickened 200, shook consumer confidence, and cost growers, shippers and retailers more than $100 million in lost business.

Specifically, the consortium wants growers to work with federal regulators, academia and industry research scientists to standardize food-safety requirements.

The group wants a process for updating the rules as more is learned about how diseases are spread from the farm to the dinner table, said Tim York, president of Markon Cooperative, a Salinas, Calif.-based buyer for food distributors.

The produce industry must work quickly "to protect public health and work toward restoring consumer and buyer confidence in fresh produce," the companies said in an Oct. 26 letter to the Produce Marketing Association, United Fresh Produce Association and Western Growers.

"It is just flat out incumbent on us to get this right. Doing nothing is the wrong answer," said Frank Padilla, Costco's chief produce buyer.

Growers agree that the industry needs better methods for establishing and enforcing food-safety practices, but there is some question whether such a program can be in place by the Dec. 15 deadline set by the retailers and distributors.

"We can't maintain the status quo," said Kathy Means, vice president of government relations for the Produce Marketing Association, a trade group of produce shippers, processors, distributors and other suppliers. "And we can't have any more mistakes."

A survey the association conducted in October found that 22 percent of respondents voiced a lack of confidence in the safety of fresh produce in general, not just spinach, she said.

Growers use a hodgepodge of safety measures and procedures to raise crops.

"Some are not following good practices," Means said.

As the spinach crisis unfolded in September, the lack of reliable industry standards became apparent, York said.

Investigators suspect the recent E. coli outbreak resulted from wild pigs tracking manure from a cattle ranch into spinach fields in California's Salinas Valley. But the cause also might have been wind- or waterborne.

Monday, Western Growers, which represents about 3,000 farmers in California and Arizona, proposed stricter rules and enforcement procedures for water and soil testing, worker sanitation and other farm operations.