Aflatoxins and fumonisins, the two most important classes of mycotoxins in corn, are associated with pre-harvest ear rots caused by Aspergillus flavus andFusarium verticillioides, respectively. These mycotoxins have been linked to numerous acute and chronic disorders in animal species, and both are classified as human carcinogens. The US Food and Drug Administration (FDA) has established allowable levels of mycotoxins in food and feeds. Thus, mycotoxin contamination can significantly reduce market value, which in disease outbreak years often results in severe economic losses for corn producers. Together, aflatoxins and fumonisins are estimated to cost US corn growers $300 million annually. Economic losses also are incurred on animal producers due to poor animal health caused by contaminated feed.
Although A. flavus and F. verticillioides each have a distinct mode of pathogenesis, a common set of conditions favors infection by these two fungi, and the two diseases often co-occur in the same growers’ fields. Extensive breeding efforts over the last 25 years have not provided adequate resistance to mycotoxin accumulation, which occurs chronically in the southeastern and southern US and sporadically in the Corn Belt. Mycotoxin mitigation tools currently available are few in number and only partially effective. Bt resistance in corn can reduce fumonisin contamination, but is inconsistent for aflatoxin control. Viable biological control approaches are emerging for A. flavus, but are not currently available for F. verticillioides. None of these options alone adequately ameliorates the risk of fumonisins or aflatoxins in corn to an acceptable level. Furthermore, available management tools have not been optimized and fully incorporated into Best Management Practices (BMPs) for growers. Thus, comprehensive and sustainable management strategies are needed urgently to reduce the risk of mycotoxin contamination of corn.
