A Chinese plant scientist at the University of Michigan, who gained national attention in June 2025 when she was arrested and charged, along with another Chinese scientist, with illegally introducing a crop-damaging fungus into the United States, pleaded guilty on November 12, 2025, to charges of smuggling and making false statements to the FBI. Under her plea agreement, Yunqing Jian, 33, was sentenced to time already served and was expected to be deported.
His arrest put the spotlight on Fusarium graminearum, a harmful pathogen. While its risk to grains such as wheat, corn, and rice may be alarming, Fusarium is not new to American farmers. The U.S. Department of Agriculture estimates it costs wheat and barley producers more than $1 billion a year.
Tom Allen, extension and research professor of plant pathology at Mississippi State University, explains what Fusarium graminearum is and is not.
What is Fusarium grass?
Fusarium graminearum is a common phytopathogenic fungus that causes problems for farmers throughout the United States.
It causes a disease in barley and wheat called fusarium head blight or scab. It can also damage rice and rot corn cobs and stalks. In severe cases, scab can reduce the yield of a crop by up to 45%.
Scab was responsible for some of the largest annual crop losses in the United States. In 2024, estimates from extension and research plant pathologists indicated that scab reduced the US wheat crop by approximately 31 million bushels, or about 2%.
Compared to other wheat diseases that damage the ear and kernels, scab is by far the most worrying, as it occurs over wide areas and affects the crop in advanced stages of growth.
We recommend: The growing trend of microdosing psychoactive mushrooms is causing an increase in visits to emergency rooms and calls for poisoning
Why is Fusarium graminearum a concern?
As a phytopathogen, the fungus responsible for scab produces a mycotoxin in grain that can be harmful to humans and livestock. Additionally, when wheat used for seeds is infested with the fungus, the seeds are less likely to germinate and produce new plants in the following growing season.
Mycotoxin is generally classified as vomitoxin. It can cause vomiting if ingested in high enough concentrations, but prolonged exposure can also cause gastrointestinal damage, weaken the immune system, and inflame the central nervous system.
In animals, repeated exposure to mycotoxin in food can decrease their growth and weight, and livestock can develop an immune response to the toxin that can affect their reproductive capacity.
The U.S. Food and Drug Administration (FDA) issued guideline levels, which are basically limits for the amount of mycotoxin considered a health risk in grain products.
Since barley and wheat are important as food for humans and livestock, harvested grain is routinely analyzed when farmers take their crops to silos for sale. Entire shipments of grain may be rejected if mycotoxin concentrations above FDA limits are detected.
Wheat can be treated to remove damaged grains. If mycotoxin levels are not too high, it could also be used as livestock feed. The reference threshold for this mycotoxin is higher for cattle and adult chickens (10 parts per million) than for humans (1 ppm).
What does the law say about the importation and transfer of plant pathogens?
These risks are why the importation and even movement of plant pathogens within the United States are regulated by the United States Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS), through the Plant Protection Act of 2000.
Federal law restricts the transfer of plant pathogens, including bacteria, fungi, and viruses, even for research purposes, as well as their release into the environment. A scientist wishing to move a plant pathogen, either within the United States or from outside the country, must obtain a permit from USDA-APHIS, which can take up to six months.
The goal of these standards is to reduce the risk of introducing new pathogens that could be even more harmful to crops.
Even with Fusarium graminearum, present on every continent except Antarctica, there is the possibility of introducing new genetic material into the environment, material that may exist in other countries but not in the United States and that could have detrimental consequences for crops.
You may be interested in: UNAM scientist alerts about fungi that cause up to 30% of liver cancer cases
How are Fusarium graminearum infections controlled?
Fusarium graminearum infections generally occur during plant flowering, rains, and periods of high humidity during the early stages of grain production.
Wheat in the southern United States is prone to infection during the spring. As the season progresses, the risk of fusariosis spreads northward across the United States and into Canada as grain crops mature in the region, with continued periods of favorable weather throughout the summer.
Between seasons, Fusarium graminearum survives on barley, wheat, and corn plant residues left in the field after harvest. It reproduces through microscopic spores that can travel long distances with wind currents, spreading the fungus over wide geographic areas each season.
In wheat and barley, farmers can control damage by applying a fungicide to developing wheat ears when they are most susceptible to infection. The application of fungicide can reduce fusariosis and its severity, improve grain weight and reduce mycotoxin contamination.
However, integrated approaches to plant disease management are often ideal, including planting scab-resistant varieties of barley or wheat, timely application of fungicides, crop rotation, and tilling the soil after harvest to reduce residues where Fusarium graminearum can survive the winter.
While applying fungicides can be beneficial, they only offer some protection and do not cure scab. If the environmental conditions are extremely conducive to scab, with abundant humidity during flowering, the disease will occur, although to a lesser extent.
Plant pathologists are making progress in developing early warning systems for farmers. A team from Kansas State University, Ohio State University and Pennsylvania State University has been developing a computer model to predict the risk of scabies. Its wheat disease predictive model uses historical and current environmental data from weather stations across the United States, along with current conditions, to develop a forecast.
In higher-risk areas, plant pathologists and commodity specialists recommend wheat growers apply a fungicide during periods when the fungus is likely to grow, to reduce the chances of crop damage and the spread of mycotoxins.
*Tom W. Allen is an associate research professor in plant pathology at Mississippi State University.
This text was originally published in The Conversation
Follow us on Google News to always stay informed
