FUNGAL INFESTATION AND MYCOTOXIN CONTAMINATION OF SOUTH-AFRICAN COMMERCIAL MAIZE HARVESTED IN 1989 AND 1990

The incidence of seedborne fungi and contamination by their respective mycotoxins were determined in commercial South African maize harveste d in 1989 and 1990 from the five major production areas. Differentiati on was made between yellow and white maize as well as between the diff erent commercial grades. I;rte predominant fungus was Fusarium subglut inans, followed closely by F. moniliforme. The mean levels of F. monil iforme were highest in the northern Orange Free Stare and the western Transvaal, whereas the levels of F. subglutinans were highest in the e astern Free State and eastern Transvaal In Natal, the mean level of F. moniliforme increased sharply in 1990 compared to 1989. Very few isol ates of Aspergillus flavus and none of A. parasiticus were recovered. Fungal isolations and mycotoxin levels were higher in 1990 than 1989. The fumonisins, a group of mycotoxins produced by F. moniliforme, were more frequently detected and at higher levels than the mycotoxins mon iliformin, deoxynivalenol and nivalenol. No zearalenone or aflatoxin w as detected in the samples. Higher levels of F. moniliforme were found in yellow than in white maize, but white maize contained higher level s of fumonisin contamination than yellow maize.