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Postharvest Pathology and Mycotoxins

Reduction of Aflatoxin Contamination in Corn by Irrigation and Tillage. G. A. Payne, Associate professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616; D. K. Cassel(2), and C. R. Adkins(3). (2)Professor, Department of Soil Science, North Carolina State University, Raleigh 27695-7616; (3)Research assistant, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. Phytopathology 76:679-684. Accepted for publication 15 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-679.

The influence of irrigation and subsoiling on infection and aflatoxin production by Aspergillus flavus in corn kernels was studied over a 4-yr period. Corn was grown on the Atlantic Coastal Plain in a humid environment on a soil with a tillage-induced pan. The corn crops were under natural drought stress each year, and stress was alleviated with a normal or delayed irrigation regime. Corn ears were either silk-inoculated, wound-inoculated, or naturally infected. Aflatoxin levels in naturally infected corn exceeded 80 μg kĝ¹ in the nonirrigated, nonsubsoiled plots each year and exceeded 1,200 μg kĝ¹ in the year with the least rainfall. Kernel infection and aflatoxin contamination were always greater in silk-inoculated plots than in naturally infected plots. Wound inoculation resulted in the greatest amount of aflatoxin, but this procedure was so severe that few treatment differences were observed. In silk-inoculated corn, aflatoxin contamination was less each year in plots that were either irrigated or subsoiled. Although several factors may contribute to high amounts of aflatoxin in the field, water stress appears to be a major factor affecting aflatoxin contamination, because subsoiling as well as irrigation reduced aflatoxin contamination.