Nancy Brooker believes the cure for most soybean diseases can be found in the soybeans themselves, or in other plants.
That has been the focus of a research project funded by the Kansas Soybean Commission.
Brooker, a biologist at Pittsburg State University, Pittsburg, KS, is concluding the four-year study with Kansas State University agronomist Jim Long. They're looking at the potential of lipids and fatty acids extracted from plants to inhibit the growth of organisms that cause foliar diseases.
"There are things already out there in nature, and we're just exploiting them for different purposes," says Brooker.
She began her study in the lab, infecting greenhouse plants with fungi grown in petri dishes, then applying the lipids and fatty acids.
One fatty acid was 95-99% effective at inhibiting stem and pod blight, frogeye leaf spot and tan spot.
Positive results in the lab took the researchers to the field. Long is especially anxious to find out if a compound derived from the lipids and fatty acids will inhibit charcoal rot. Common in hot, dry areas, charcoal rot causes as much as a 30% reduction in yield. Up to this point, the only way to manage the soil-borne fungus was with crop rotation.
"We're probably never going to get it out of the soil, but we can manage it so it doesn't take such a dramatic toll on yield," says Brooker.
In this case, the disease-fighting compound was applied to the soybean seed. Studies have shown, says Brooker, that charcoal rot infects plants shortly after germination, but symptoms don't show up until later, when the crop is stressed.
Although the seed treatment's effect on charcoal rot hasn't been fully analyzed, preliminary results suggest that it increases yield in the presence of the disease.
"We've seen larger seeds and more seeds on plants in our treated plots," Brooker reports.
She says the treatment "has the ability to possibly move the plant in and out of certain time periods of growth when it's most critical that they be in a healthy situation and not stressed."
She believes the research might lead to the next generation in disease control. It's needed, she says, in part because fewer chemicals will be available to farmers in the years ahead.
"I think that it's naive to ever say that one thing will completely displace another, but what we're doing may become more and more feasible as our choices become fewer and fewer."
She says several companies are already looking at biological control of weeds, insects and diseases. Further in the future, though, the needed disease protection may come from biotechnology.
"There is potential down the road to engineer plants to produce these lipids to protect themselves from foliar diseases," she says.