WASHINGTON, D.C.--A fungus called Fusarium head blight, or "scab," has destroyed more than $2.6 billion worth of wheat and barley in the past decade. Now research presented 21 August at the American Chemical Society meeting here suggests a new way to combat the blight. The strategy is to add certain microorganisms, which reduce infestation rates by gobbling up nutrients that the fungus needs to overwhelm the plant.
Fusarium head blight is not a new disease, but it has made a resurgence over the last 10 years. The fungus has plagued most of the eastern half of the United States, partly due to tilling practices and unusually wet weather when the plants are most vulnerable to infection. Fusarium infects the flowering heads of the plants, bleaching them and sometimes causing the entire grain-bearing portion to fall off. Even if the fungus doesn't kill the plant, it produces a toxin called deoxynivalenol--better known as "vomitoxin" for the reaction it causes in pigs--that shrinks and discolors the grains.
To combat the growing problem, plant pathologist David Schisler and his team at the U.S. Department of Agriculture's (USDA's) Agricultural Research Service in Peoria, Illinois, along with colleagues at Ohio State University in Columbus, looked for microorganisms that might compete with the fungus for food. Schisler's team isolated two bacilli and four yeasts, and measured their ability to metabolize choline, a chemical produced in the flowers of the wheat that stimulates the growth of the fungus. In greenhouse tests, the microorganisms reduced the severity of the fungal infections by 95%; in field tests, they cut fungus levels by 56% without any side effects.
Schisler says this approach is safer than fungicides and easier than genetically engineering resistance to fungi. The technique "certainly has the potential to be important," says Brad Hillman, a plant pathologist at Rutgers University in New Brunswick, New Jersey. "If you can get good biocontrol, you can reduce the use of fungicides as well as reduce the natural toxins."
The USDA's Agricultural Research Magazine story featuring Fusarium blight
Fermentation Biochemistry Research at the USDA's National Center for Agricultural Utilization Research