Technical Abstract: Contamination of certain crops with aflatoxins is a serious concern for agriculture and animal and human health. The predominant species associated with this crop contamination is Aspergillus flavus. The ability of A. flavus to produce other toxins could also be an additional concern. Phylogenetic evidence suggests that this species has a history of recombination and has relatively recently adapted to growth on plants from a normally saprophytic terrestrial existence. Efforts to control aflatoxin contamination involve pre-harvest introduction of non-aflatoxigenic competitors, as well as enhancement of the resistance of affected crops against fungal infection.