The Mendocino County district attorney is advising medical marijuana growers to tag their plants with sheriff-issued zip ties to lessen their chances of prosecution.

"Participation (in the zip-tie program) will continue to be one factor considered by the prosecuting attorney if allegations come before him of criminal wrongdoing," Mendocino County District Attorney David Eyster said in a written statement issued Thursday afternoon.

Skeptics question whether it's a good idea to register pot-growing operations with the sheriff's office, given the recent federal crackdown on cooperatives, dispensaries and the people who rent to them.

"It seems to me growers wouldn't want to be on any record when they know that the justice department is so closely looking over the shoulder of Mendocino County," said Mendocino County Supervisor Dan Hamburg, who also is a medicinal marijuana patient.

Eyster issued the statement to address confusion about local medical marijuana regulations that has arisen since the county ended its permitting process, which allowed up to 99 plants, said Mike Geniella, spokesman for the district attorney's office. The county abandoned the permits earlier this year after federal authorities threatened legal action. Marijuana growing remains illegal under federal law and the U.S. Department of Justice last year began cracking down on pot growing and selling operations, including ones approved by the county.

The county's ordinance now limits pot growing to 25 plants per parcel.

The sheriff's office zip-tie plant identification program has been unaffected by the crackdown, Eyster said. It continues to be a safeguard against prosecution for legal growers, he said. It's a voluntary program for most, but mandatory for pot growers who are on probation, he added.

The zip-tie program is aimed at reducing unnecessary prosecutions and protecting medical marijuana patients, as the ties indicate sanctioned growing. It also generated $370,100 in revenue in the last eight months, according to the sheriff's office.

The revenue is expected to decline significantly now that permits for gardens of more than 25 plants have been abolished. The majority of zip-tie income — $305,750 — came from the larger cooperatives that are now prohibited. They were paying twice as much per zip tie as the small-scale growers, which generated $64,350.