Effect of Temperature on the Preharvest Infection of Maize Kernels byAspergillus flavus

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Abstract
The effect of temperature on colonization of maize [Zea mays] silks and the subsequent invasion of kernels by Aspergillus flavus was studied in controlled environments. At the postinoculation temperature regimes of 34/30 C (34 C .times. 9 hr, 30 C .times. 15 hr) and 26/22 C, as many as 28 and 2.4% of the kernels, respectively, were infected. Infected kernels were present in all areas of the ear, and neither temperature nor time of inoculation affected the location of infected kernels on the ear. At 34/30 C the fungus entered the ear tip in one day and was present in the base by 4 days. Internal infection of the ear did not occur until 8 days after inoculation, and the percentage of infected kernels increased greatly between 28-32 days, when kernel moisture was < 32%. These results demonstrate that the parasitic ability of A. flavus is enhanced at high temperature and that, although surface colonization of the kernels occurs early, extensive internal infection does not occur until kernel maturity.