Production Blog

JEFFERSON CITY, Mo. (DTN) -- This week, it was widely reported that two Chinese nationals had been charged in federal court in Michigan for allegedly smuggling an agricultural pathogen into the United States that is responsible for billions in economic losses worldwide each year.

What wasn't widely reported was that this pathogen is already here -- and something that farmers have been accustomed to dealing with for decades.

The fungus in question, Fusarium graminearum, is native to North America and well known -- even if its scientific Latin name isn't. Most U.S. farmers are more apt to simply call it "scab" or "head blight" when it infects wheat or "gib," short for Gibberella ear rot, when it infects corn.

"The news stories that I first read made it seem like this was a new pathogen coming in, and that's not the case," said Damon Smith, University of Wisconsin Extension field crops pathologist, during a phone interview with DTN. "Fusarium is widespread. I mean, it's everywhere. You could probably go out in your yard and find Fusarium in the dirt. It's that common. We've been dealing with it in the Midwest since like 1990."

In wheat, Fusarium head blight is considered the most economically important wheat disease in North America. It reduces both yield and grain quality, producing mycotoxins that affect human and animal health. Fungal spores are carried to the wheat heads and can be abundant during wet weather. Most infections occur during flowering because anthers and pollen serve as a food source for the fungus. Head blight is more severe in reduced or no-till fields and especially if wheat follows corn in the rotation.

Yield reductions and loss of grain quality also occur when Fusarium infects corn and Gibberella ear rot develops. Its occurrence also can increase in fields where corn follows corn or where corn follows wheat affected by head blight. The fungus almost always begins at the tip of the ear and can be identified most readily by the red or pink color of the mold.

Fusarium can produce two mycotoxins: deoxynivalenol and zearalenone. The first, a vomitoxin often called "DON," can induce vomiting and other gastrointestinal issues in livestock. The second can affect animal reproductive systems. Smith noted there can be regional differences among strains of the fungus that make some of the individual pathogens more aggressive than others.

"So, the vomitoxin they produce can actually have a slightly different chemical makeup, and that chemical makeup will actually make them more or less toxic," he explained. "I've done surveys across Wisconsin, for example, where we've looked at Fusarium. We've identified the species and then we look at their toxic signature, if you will. We call them chemotypes."

These chemotypes are something that pathologists keep track of, and Smith said that it's not uncommon for researchers like himself and others to import strains of Fusarium from other states or even other parts of the world to increase their understanding of the pathogen and improve plant disease management.

"I exchange Fusarium isolates with my colleagues all the time for research purposes, but we do it through APHIS (USDA Animal and Plant Health Inspection Service)," Smith said. "We have permits to do that. We follow some pretty important guidelines. So, one of the things that sort of raises a little bit of an eyebrow when we talk about this situation (the alleged smuggling of Fusarium) is which chemotype was it? Could it have been an isolate that maybe was a little more aggressive or had a different chemotype? That's something you wouldn't want to have released."

Smith added that because of decades of experience managing Fusarium diseases, the U.S. agricultural industry has a system in place to protect the food supply. Agronomically, plant breeders have worked to increase fungal resistance in wheat varieties and corn hybrids. Fungicides have been developed to prevent these fungal diseases or reduce their severity. And testing protocols have been established at grain elevators and other points along the grain stream to ensure that mycotoxin levels remain within safe guidelines.

"Here in Wisconsin, if I talk to a farmer about Fusarium head blight, they'd be like, 'We deal with that all the time,'" Smith said. "Our dairy farmers are very cognizant of vomitoxin. Their nutritionists are testing every day for it."

Read more from DTN:

-- "US: Chinese Nationals Smuggled Pathogen," https://www.dtnpf.com/…

-- "Production Blog: Don't Get Glib About 'Gib' This Fall," https://www.dtnpf.com/…

Learn more about Fusarium head blight here: https://cropprotectionnetwork.org/…

Learn more about Gibberella ear rot here: https://cropprotectionnetwork.org/…

Jason Jenkins can be reached at jason.jenkins@dtn.com

Follow him on social platform X @JasonJenkinsDTN

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