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Annual losses to aflatoxin are estimated at some $190 million. Paul Williams, USDA-ARS researcher/geneticist, and his Mississippi-based team are learning to combat the disease through corn breeding and molecular markers.
With corn acreage surging, Mid-South growers expected a bountiful, profitable 1998 harvest. Then, aflatoxin rode in on a pale horse and ruined the party. The fungal toxin proved devastating for a large group of growers.
When aflatoxin levels reach 20 parts per billion, affected corn can’t be shipped across state lines and elevators shy away. Aflatoxin can easily lead to food and feed safety issues. Annual losses to the disease are estimated at some $190 million.
“Many years, there are localized problems with aflatoxin,” says Paul Williams, a USDA-ARS research geneticist based on the Mississippi State University campus. “But 1998 hit the Mid-South very, very hard.”
Williams remembers the post-harvest reaction.
“Folks called when they found out we were researching aflatoxin. They were looking for answers. When researching something like aflatoxin contamination, you can labor in obscurity until the problem shows up in a serious way. At those times, everyone wants to know what you’re doing and if research has shown any solutions.”
To reduce the incidence of aflatoxin, handling corn at harvest and post-harvest is very important. Growers need to get grain in and stored quickly at 12 to 13 percent moisture. That will keep the fungus from growing and producing toxin.
Williams believes some of the aflatoxin events — “and there was already fungus and toxin” — were exacerbated by the lack of adequate drying facilities on some farms. There were too few drying units to handle the amount of corn being harvested.
“Growers were trying to dry down their corn in rice dryers and trying other things. I don’t know if the region was quite ready for all that corn.”
Lesson learned, shortly thereafter, grain dryers and storage bins were erected throughout the Mid-South.
“Interestingly, I recently read a piece saying that Kenyans were having a problem with aflatoxin contamination. That was tied — just like in the Mid-South — to having inadequate facilities for handling the crop after harvest.”
Williams began his aflatoxin research in the mid-1990s.
“Some of the scientists in the group I work with had begun researching the problem in the late 1970s. At that time — 1977, I believe — aflatoxin contamination was a big problem and it sparked interest in some of my colleagues.”
Is the research focus on breeding corn that can resist aflatoxin or suppression through other means?
“Our focus is on breeding but we realize that genetics could be just one component of the solution. We’ve been working with an MSU agronomist this year to see how our germplasm reacts in a system using the atoxigenic strains in biocontrol.
“There’s an ARS group based in Stoneville, Miss., that is working on the biocontrol aspect. They’ve used our germplasm for some experiments.”