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This review presents the different mycotoxins (aflatoxins, fumonisins and ochratoxin A) produced in agricultural crops in the West African sub-region. The acute and chronic toxic effects of the various mycotoxins are presented. Maize and groundnuts have been found to be excellent substrate for aflatoxin contamination, while fumonisins are widely distributed in maize. Other food products for which mycotoxin contamination has been reported in the sub-region include dried yam chips, tiger nut, melon seeds and stored herbal plants. Mycotoxin contamination is favoured by stress factors during plant growth, late harvesting of crops, high ambient humidity preventing thorough drying, unscientific storage practices and lack of awareness. Control measures include education of the populace on the danger of mycotoxin contaminated diet, early harvesting, rapid drying, sorting, sanitation, use of improved storage structures, smoking, insect control, the use of botanicals and synthetic chemicals as storage protectants, fumigation, biological control, the use of resistant varieties and detoxification of mycotoxin contaminated grains.

Dried yam chips from different markets in western Nigeria had pH 5.7–6.1 and moisture contents of 7.5–14.3%. Aspergillus was the predominant mould followed by Penicillium. From thin layer chromatography analysis, 54% of the chips were contaminated with aflatoxin B1 up to 186 (g/kg, 32% with aflatoxin B2 up to 55 (g/kg. Of the samples, 51% contained aflatoxin above the 20 ppb internationally accepted residue limit. Copyright © 2003 Whurr Publishers Ltd

The efficacy of some fungal and bacterial isolates obtained from cowpea phylloplane in inhibiting the in vitro and in vivo growth of Colletotrichum lindemuthianum, causal agent of anthracnose of cowpea was investigated. Inhibition of growth of the pathogen with production of zones of inhibition was observed for Aspergillus flavus, A. ochraceus, Penicillium aurantiogriseum, Bacillus subtilis-BS21, B. subtilis-BS22 and B. subtilis-BS23. Inhibition of growth on contact was recorded for A. niger while Trichoderma viride-TH14 and T. viride-TH31hyperparasitized the pathogen. The two isolates of T. viride and all tested bacteria significantly reduced seedling infection from anthracnose infested seeds in pot experiments. Spray application of T. viride-TH31 on inoculated cowpea plants in the field effectively suppressed the incidence and severity of anthracnose disease, and significantly increased yield over the control. The antagonist was more effective when applied twice weekly than once in a week.

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