Kernel Infection and Aflatoxin Production in Maize by Aspergillus flavus Relative to Inoculation and Harvest Dates. GENE E. SCOTT, Mississippi Agricultural and Forestry Experiment Station, Mississippi State 39762. NATALE ZUMMO, USDA-ARS and Mississippi Agricultural and Forestry Experiment Station, Mississippi State 39762. Plant Dis. 78:123-125. Accepted for publication 7 October 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1994. DOI: 10.1094/PD-78-0123.

Preharvest kernel infection by Aspergillus flavin and subsequent aflatoxin contamination of maize (Zea mays) grain is a chronic economic problem in the southern part of the United States. Studies were conducted to determine the time of inoculation and harvest date most effective for identifying maize genotypes resistant to kernel infection and aflatoxin contamination by A. flavus. Inoculation of ears with A. flavus 6 days after midsilk resulted in as many or more infected kernels than inoculation of ears 12 and 18 days after midsilk. Multiple inoculations did not increase incidence of kernel infection or aflatoxin contamination. The percentage of infected kernels in inoculated resistant and susceptible hybrids was similar at 46 and 50 days after midsilk, but the percentage of infected kernels was greater in susceptible hybrids at later harvest dates. Thus, resistant hybrids differed significantly from susceptible hybrids for infection levels for harvest dates of 54-62 days after midsilk. One susceptible hybrid had markedly higher aflatoxin contamination than the other three hybrids. Selection for resistance to A. flavus should be more effective at harvest dates around 60 days after midsilk than when grain reaches physiological maturity.