Interview with David Geiser

David Geiser, professor of plant pathology and environmental microbiology. PHOTO: STEVE WILLIAMS


Steve Williams: I’ll ask the obvious question: what is Fusarium?

David Geiser: Fusarium is a very common fungus found in just about every environment on Earth.


SW: And why is it important to study?

DG: There are a couple reasons. First, as a plant pathogen it causes a wide variety of plant diseases, including some of the worst in the world—such as Panama disease of banana, which wiped out banana production in Central America in the mid-twentieth century—and all kinds of problems on cereal crops.


SW: What kinds of problems arise with cereal crops?

DG: Fusarium is a major toxin producer. A Fusarium species will infect wheat; an infection won’t wipe out the crop but can render it useless by creating different mycotoxins—toxic chemicals produced by fungi that are toxic to animals, including humans.


SW: Is it a big problem?

DG: It’s a major concern for wheat, barley, and corn growers. Fusarium contaminates cereals with toxins. With more corn being processed into biofuels, the corn by-products from a mycotoxin-infected crop can’t be used for anything because it’s effectively hazardous waste that has to be disposed of in a very expensive manner.


SW: What about its role as a human pathogen? 

DG: Certain species can cause life threatening infections in severely immune-compromised people. People who are in the hospital undergoing chemotherapy before a bone marrow or organ transplant where doctors wipe out their immune system are infected. Fusarium is normally a harmless element in the environment. With an immune-compromised patient, it can cause a deadly infection. 


SW: Anything positive about Fusarium?

DG: Sure. In nature its role as an endophyte is important. It grows in the plant, but it doesn’t hurt the plant. It may even be beneficial to plants to have Fusarium present, helping the plant to tolerate stress or resist insects or disease. Other species work in the soil to break down plant matter and probably everything else. 


SW: Are there possible commercial uses on the horizon? 

DG: Fusarium can do some other interesting things. We have isolates that come from oil-contaminated water and indications are they might be breaking down long-chain hydrocarbons. So there’s potential for use as a bioremediator. 


SW: Tell me about the Fusarium Research Center at Penn State.

DG: Primarily, it’s a culture collection. We house a little over 20,000 different strains of Fusarium collected from all over the world. In addition to supporting my own research, we support research in this field by making isolates in our collection available to other scientists who are legally authorized to take possession of samples. There are a number of Fusarium culture collections in the United States and around the world, but we’re probably the largest.


SW: A question I always ask when I’m looking at stories for the magazine: if I were a legislator sitting in Harrisburg, why should I care about Fusarium?

DG: Mycotoxins are probably number one on the list in Pennsylvania. We’re seeing more of them, particularly mycotoxins associated with cereals. Concern is growing for something called DON (Deoxynivalenol, or vomitoxin). Growers are having crops rejected at processing plants. The last couple of years it’s been getting worse—not just in Pennsylvania, but elsewhere in the country. Is it climate change? Agricultural practices? A combination? We don’t know. There have been changes in the population of Fusarium where it’s getting more virulent and more toxigenic. We know it’s happening in Canada, but we aren’t sure yet about Pennsylvania. If Pennsylvania wants to grow more cereals for food, feed, and biofuels, mycotoxins are going to be an increasing concern. It’s a serious problem for growers. There’s a lot of work to do.