Effect of inoculation time and point of entry on disease severity in Fusarium graminearum, Fusarium verticillioides, or Fusarium subglutinans inoculated maize ears1

To determine if differences exist in the ability of three Fusarium species (F. graminearum, F. verticillioides, and F. subglutinans) to infect maize ears as the silks and kernels mature, one moderately resistant and two susceptible hybrids were inoculated at two points of entry (silk channel and kernels) in 1994 and 1995. Inoculations were conducted nine times for each part of the ear starting from silk emergence. For all three species, the greatest silk channel inoculated disease severities occurred when the ears were inoculated in the early stages of silk development, with a peak in susceptibility around 1–6 days after silk emergence, followed by a rapid decrease in severity. With kernel inoculations, a general decrease in disease severity occurred with time for all species. Fusarium verticillioides had the lowest disease severity of the three species. With silk channel inoculations, F. subglutinans resulted in higher disease severity than F. graminearum; however, the opposite was found with kernel inoculations, with F. graminearum producing the greatest amount of disease symptoms.