Is artificial inoculation or natural infection better for evaluating forage maize cultivars for resistance to fumonisin contamination?

Abstract

Several Fusarium species can contaminate forage maize with fumonisin toxins, but levels can vary depending on cultivar resistance. When maize cultivars were evaluated for levels of fumonisin contamination, fumonisins in 31P41 were very low after natural infection without inoculation but were as high as in other cultivars after wound inoculation, whereas SH3815 was low under both conditions. We supposed that 31P41 was contaminated with a high level of fumonisins after wound inoculation because it had only physical barriers to fungal infection, whereas SH3815 had post-infection defense. However, injuring kernels without inoculation resulted in a high level of contamination in SH3815, thus discounting post-infection defense. Since it is unclear what type of defense is being evaluated in cultivars after wound inoculation, natural infection is preferred for the evaluations.