Officials in at least four states are urging residents to report any unsolicited packages of seeds that appear to have been sent from China, warning that they might be invasive or otherwise harmful.
The agriculture departments in Washington State, Louisiana, Kansas and Virginia have issued statements in recent days, noting that residents had reported receiving packages of seeds in the mail that they had not ordered. Based on photos, the seeds appear to have been mailed in white pouches displaying Chinese lettering and the words “China Post.”
Some of the packages were labeled to say they contained jewelry, according to the Kansas Department of Agriculture.
Packages of seeds have also been sent to residents in Utah, Arizona and Ohio, according to local news reports.
Officials are warning people not to plant the seeds.
“Unsolicited seeds could be invasive, introduce diseases to local plants or be harmful to livestock,” the Washington State Department of Agriculture said in a statement.
The police in Whitehouse, Ohio, where a resident reported receiving seeds, said the packages appeared to be a part of a “brushing” fraud.
“A brushing scam,” the department said on its Facebook page, “is an exploit by a vendor used to bolster product ratings and increase visibility online by shipping an inexpensive product to an unwitting receiver and then submitting positive reviews on the receiver’s behalf under the guise of a verified owner.”
Although the seeds did not appear to be “directly dangerous,” the department said, “we would still prefer that people contact us to properly dispose of the seeds.”
The U.S. Agriculture Department did not immediately respond to a request for comment. However, the department’s Animal and Plant Health Inspection Service encourages people to report “potential smuggling of prohibited exotic fruits, vegetables or meat products.”
Mike Strain, the commissioner of the Louisiana Department of Agriculture and Forestry, said in a statement on Friday that people should notify his department if they had received an unsolicited package of seeds.
“Right now, we are uncertain what types of seeds are in the package,” Mr. Strain said. “Out of caution, we are urging anyone who receives a package that was not ordered by the recipient to please call the L.D.A.F. immediately. We need to identify the seeds to ensure they do not pose a risk to Louisiana’s agricultural industry or the environment.”
The Chinese Embassy in Washington did not immediately respond to a request for comment.
Carolee Bull, a professor who leads the Department of Plant Pathology and Environmental Microbiology at Penn State University, said that planting unidentified seeds could be harmful.
“The reason that people are concerned is — especially if the seed is the seed of a similar crop that is grown for income and food, or food for animals — that there may be plant pathogens or insects that are harbored in the seed,” she said.
Seed introduction is tightly regulated in the United States, Professor Bull said. The Plant Protection and Quarantine program, which is operated by the Agriculture Department’s Animal and Plant Health Inspection Service, has strict rules for the importation of plants and seeds.
“Say that when I import seed into the country that has not been here before — wheat seed, for example — I know they’ll bring it in and they’ll actually grow it out at the A.P.H.I.S. facility to check it for disease,” Professor Bull said.