Technology developed by researchers at The Ohio State University and the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS) will help manage the spread of one of the worst diseases affecting crops wheat and barley.
The licensed technology is a yeast that offers a “green” method to protect cereal crops from a devastating fungal disease. Researchers worked nearly 12 years to develop, identify and patent the naturally occurring yeast — isolated from Ohio fields — as a biological control method for controlling Fusarium graminearum, the fungus that causes Fusarium head blight or head scab.
The technology has been licensed to Sci Protek, Inc., based in Vista, Calif.
Annual crop losses from the fungus in the U.S. alone exceed $1 billion per year. In addition, consumption of diseased grains causes human and animal disease and epidemics in developing world countries
Mike Boehm, professor and chair of Ohio State University’s Department of Plant Pathology and a plant pathologist and principal investigator with the Ohio Agricultural Research and Development Center, says that biological control gives growers additional options for disease management.
“There are many ways to manage disease: genetics, crop rotation, fungicides and biological control or the use of beneficial microorganisms,” Boehm says. “This isn’t the first biological control labeled for managing head scab, but a ‘green’ fungicide is advantageous. It allows for managing head scab during a targeted time frame that chemical fungicides may not adequately provide.
"In addition, the product could be used in organic production where fungicides are not a tool or in situations where fungicide use is restricted.”
Controlling head scab is important. The fungal pathogen affects cereal grains, specifically wheat and barley, during the crop’s flowering period. In addition, the fungal pathogen infects corn, causing stalk rot, and may lead to lodging.
The disease causes yield losses, and produces a mycotoxin, known as vomitoxin, that is harmful to livestock and humans if eaten. Infected grain submitted to grain elevators as livestock feed or to be processed by millers and bakers can be rejected. During head scab epidemics, an entire crop can be wiped out.
Controlling head scab development and preventing toxin buildup, however, can be tricky. The disease only affects wheat and barley during a brief period when the plant is flowering — and then, only if environmental conditions are right.
Spraying fungicides on wheat plants prior to flowering is not very effective. Spraying fungicides after flowering can contaminate the harvested grain with chemicals.
“Control really depends on the crop’s stage of development, the weather and if and when the plant may be susceptible to attacks from the pathogen,” Boehm says. “Having such a targeted window for fungicide applications is a challenge, but also provides an excellent opportunity to use biological control.”
That’s why Boehm and his USDA-ARS colleague David Schisler turned to exploring the use of beneficial microorganisms as a means for managing this disease.
“Microorganisms are everywhere, even on plants. Some do nothing, others are parasitic and there are others that may provide a benefit to the plant," Boehm says. "Knowing this and dreaming a little bit, we set out to find microorganisms that live naturally on wheat, in particular on the wheat heads and flower parts, that can suppress the pathogen and reduce disease and toxin levels.”
During the 12 years of lab, greenhouse and field trials across the Midwest, researchers screened hundreds of beneficial microorganisms (bacteria and yeasts) they found living on the wheat plant. Out of those hundreds, seven bacteria and yeasts were identified that exhibited the behavior they were looking for. Out of that group came the yeast that has been licensed to Sci Protek, Inc.
The yeast, known as Cryptococcus noadensis, has been found to reduce disease severity by as much as 50%, while at the same time significantly reducing the amount of toxin in the infected grain. Researchers suspect the biocontrol yeast functions by either gobbling up the nutrients on the wheat flowers that the fungal pathogen needs to grow and colonize, or by feeding on the pathogen directly.