Ear-rot fungi and mycotoxins in South African corn of the 1989 crop exported to Taiwan

Abstract

A shipment of South African corn (1989) exported to Taiwan, was analyzed for various ear-rot fungi and Fusarium mycotoxins. Two sets of samples, one from the points of origin in South Africa prior to shipment, and the other from the end-point distributors in Taiwan, were studied. Surface-sterilized kernels were plated onto two different agar media and the fungal colonies identified. High Performance Liquid Chromatography was used to analyze mycotoxin levels. The predominant ear-rot fungi, in decreasing order of isolation frequency, were Fusarium subglutinans, F. moniliforme, Diplodia maydis and F. graminearum. Aspergillus flavus and A. parasiticus were not isolated from samples prior to export, but a small number of A. flavus isolates were found after shipment. The predominant mycotoxins were fumonisins B1 (0-865 rig/g) and B2 (0-250 ng/g). Low levels of moniliformin (_<390 ng/g) were detected in some samples before shipment. Zearalenone (25 ng/g), and nivalenol (120 ng/g) were detected in two out of 32 samples taken in Taiwan. The samples contained no detectable levels of either aflatoxins (> 0.5 ng/g) or deoxynivalenol (>100 ng/g) before or after shipment.