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Experts doubt FBI’s claim that crop fungus smuggled by Chinese students is a threat
By Heather Schlitz - 6/6/2025
By Heather Schlitz
CHICAGO (Reuters) -A biological sample that a Chinese researcher was accused of smuggling into the United States and that prosecutors cast as a "dangerous biological pathogen" is a common type of fungus already widespread in U.S. crop fields that likely poses little risk to food safety, experts said.
On Tuesday, U.S. federal prosecutors accused two Chinese researchers of smuggling samples of the fungus Fusarium graminearum into the U.S., describing it as a potential agricultural terrorism weapon.
Yunqing Jian, 33, a researcher at the University of Michigan's Department of Molecular, Cellular and Developmental Biology has been charged in connection with allegations that she helped her boyfriend, Zunyong Liu, 34, smuggle the pathogen into the U.S.
However, agriculture experts interviewed by Reuters this week said the fungus has been in the U.S. for more than a century, can be prevented by spraying pesticides, and is only dangerous if ingested regularly and in large quantities.
"As a weapon, it would be a pretty ineffective one," said Jessica Rutkoski, a crop sciences professor, wheat breeder and geneticist at the University of Illinois at Urbana-Champaign. Rutkoski and other researchers said extensive testing for the fungus' toxin, widespread use of fungicides and the difficulty of intentionally creating an infection with the pathogen would make it a clumsy weapon. The U.S. Attorney's Office and the FBI declined Reuters' request for comment.
Since the 1900s, U.S. farmers have been battling the fungus, which causes Fusarium head blight, usually known as "scab," which often infects wheat, barley and other grains on farms during rainy years. The telltale pink streaks on the grain heads contain a toxic byproduct called vomitoxin, which is tested for and tightly controlled by grain elevators where farmers sell their crops.
Constant testing and monitoring means that only negligible amounts of vomitoxin ever make it into the bread, pasta and cookies Americans eat, far below levels that would sicken a human, experts said.
"We have a long history of managing epidemics of scab," said Andrew Friskop, professor and plant pathologist at North Dakota State University, noting that farmers have access to many tools to prevent and control the disease. Farmers began regularly spraying their fields with fungicide as early as the 1990s, and researchers have since developed multiple strains of fungus-resistant wheat.
Plant experts said that it would be difficult to fully assess the risks posed by the samples without more information on the particular strain. But Rutkoski, whose research involves intentionally contaminating wheat with the fungus, said that she isn't always successful at infecting her test field's wheat with scab. She said the pathogen is difficult to control, and her lab has to strike the right balance of temperature and humidity to create an infection. In federal court in Detroit on Tuesday, Jian was charged with conspiracy to commit offense or to defraud the U.S., smuggling goods into the U.S., false statements and visa fraud. Jian did not comment on the charges, and the lawyer who represented her in court was not immediately available for comment. Liu could not be immediately reached for comment. The court scheduled Jian's bail hearing for June 13.
(Reporting by Heather Schlitz. Editing by Emily Schmall and Nick Zieminski)