Aflatoxin accumulation and kernel infection of maize hybrids inoculated with Aspergillus flavus and Aspergillus parasiticus

Over a three year period, we compared aflatoxin accumulation and kernel infection in maize hybrids inoculated with Aspergillus flavus isolate NRRL 3357, A. flavus isolate NRRL 19772, Aspergillus parasiticus isolate NRRL 6111, and all combinations of these isolates. Maize hybrids were inoculated with the Aspergillus strains using the side-needle technique at 7 days after midsilk (50% of the plants had silks emerged). Aspergillus kernel infection and aflatoxin contamination were determined at ca. 63 days after midsilk. A. flavus isolate 3357 induced high levels of aflatoxin contamination in the maize grain which was similar to levels found when this isolate was combined with the other two Aspergillus isolates. Kernel infection levels were higher in one hybrid when a combination of isolates including isolate 3357 was used. A. flavus isolate 3357 has been used to evaluate maize germplasm for aflatoxin resistance in the south-eastern USA for over 30 years. Our studies determined that inoculating plants with A. flavus isolate 3357 alone was sufficient for inducing aflatoxin contamination in grain at our location. A combination of A. flavus isolates which include isolate 3357 might be more effective in increasing levels of kernel infection and could also induce higher levels of aflatoxin at locations that do not favour disease development.