An inspection officer sprays chemicals on seeds and plants prior to destroying them. (Xu Cheng)
Attempts to bring in a total of about 2.5 tons of illegal seeds or infant plants to the city have been discovered so far this year, according to Shanghai Exit-Entry Inspection and Quarantine Bureau.
Some of the seeds and plants were destroyed yesterday at Pudong International Airport. These included succulents, strawberry seeds and plants, tulip bulbs and bamboo.
"The seeds and plants usually have soil with them which could contain many kinds of pests," said Ye Jun, a researcher at the bureau's inspection and quarantine technical center.
Ye said dangerous pests were found in seeds and plants of cypresses, maple trees and apple trees from Japan, and pests and weeds were often discovered with seeds of aromatic plants and beans.
The illegal seeds and plants were sprayed with chemicals and placed in an autoclave to be heated to 121 degrees Celsius. Then they were kept in the heated container for 20 minutes to ensure all harmful substances were destroyed.
The crackdown is part of a nationwide "Green Bud" initiative in force since 2015.
In Shanghai, there have been 5,405 cases in the past three years where illegal seeds and plants were discovered in luggage or mail packages with destinations in the city, and pests were found in 3,347 of those cases, with "extremely harmful pests" found in 101 of them, the bureau said.
Wan Mingwei, deputy director of the bureau, said this year it has started to create a blacklist of tourists found carrying illegal seeds or plants.