Interactions between Fusarium verticillioides, Aspergillus flavus, and insect infestation in four maize genotypes in lowland Africa

An experiment was designed to compare cycles of selection of four maize gen otypes for ear- and grain-quality characteristics, interactions with Asperg illus flavus and Fusarium verticillioides infection, and insect ear infesta tion in two seasons. Mean infection levels by A. flavus and F. verticillioi des were significantly higher in inoculated rows than in the controls. The F. verticillioides-inoculated rows had significantly more coleopteran beetl es and lepidopteran borers per ear than the controls and A. flavus-inoculat ed rows. Genotypes and cycles of selection within genotype were not differe nt with respect to number of insects or percent fungal incidence in the ear , but they were different for husk extension, field weight, 100-grain weigh t, and grain density. Inoculation with either fungus resulted in significan tly higher percentage of floaters (i.e., loss of grain density) and lower g rain weight than the controls. Aflatoxin (B1 and B2) in A. flavus-inoculate d rows averaged 327 ppb in the first season and 589 ppb in the second (drye r) season. Fumonisin levels in F: verticillioides-inoculated rows did not d iffer between seasons, with an average of 6.2 ppm across seasons. In the no ninoculated control rows, fumonisin was significantly higher in the first ( 5.3 ppm) than in the second (3.1 ppm) season. For all genotypes, husk exten sion and yield parameters decreased in the fungal-inoculated treatments. Ge neral ear-rot scoring was significantly correlated with incidence of F. ver ticillioides in kernels and grain-weight loss but not with A. flavus in the grain.