Biological control of Fusarium moniliforme in maize

Fusarium moniliforme Sheldon. a biological species of the mating population s within the Gibberella fujikuroi species complex, i.e., population A [= G. moniliformis (Sheld.) Wineland], is an example of a facultative fungal end ophyte. During the biotrophic endophytic association with maize, as well as during saprophytic growth, F. moniliforme produces the fumonisins. The fun gus is transmitted vertically and horizontally to the next generation of pl ants via clonal infection of seeds and plant debris. Horizontal infection i s the manner by which this fungus is spread contagiously and through which infection occurs from the outside that can be reduced by application of cer tain fungicides. The endophytic phase is vertically transmitted. This type infection is important because it is not controlled by seed applications of fungicides, and it remains the reservoir from which infection and toxin bi osynthesis takes place in each generation of plants. Thus, vertical transmi ssion of this fungus is just as important as horizontal transmission. A bio logical control system using an endophytic bacterium, Bacillus subtilis, ha s been developed that shows great promise for reducing mycotoxin accumulati on during the endophytic (vertical transmission) growth phase. Because this bacterium occupies the identical ecological niche within the plant, it is considered an ecological homologue to F. moniliforme, and the inhibitory me chanism, regardless of the mode of action, operates on the competitive excl usion principle. In addition to this bacterium, an isolate of a species of the fungus Trichoderma shows promise in the postharvest control of the grow th and toxin accumulation from F. moniliforme on corn in storage.