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SESSION 5: DISEASE CONTROL AND FORECASTING MODELS
P116 - The potential risk of grain colonisation by
fumonisin-producing Fusarium spp. and fumonisin
synthesis in commercial maize in South Africa
B. Janse van Rensburg 1 , N. W. McLaren 2 , B. C. Flett 1,3
1 Agricultural Research Council-Grain Crops Institute, Private Bag X1251, Potchefstroom, 2520, South
Africa; 2 Department of Plant Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300,
South Africa; 3 Unit for Environmental Science and Management, Faculty of Natural Sciences, North-
West University, Private Bag X6001, Potchefstroom, 2520, South Africa
E-mail: FlettB@arc.agric.za
Fumonisins are carcinogenic mycotoxins that are produced primarily by Fusarium
verticillioides and F. proliferatum on maize, globally. The natural occurrence of
fumonisin producing Fusarium spp. and fumonisin contamination of maize grain
were quantified in selected maize cultivars from the major production areas of
South Africa. Samples were analysed using quantitative (q) real-time PCR to
determine the respective biomasses of fumonisin-producing Fusarium spp.
Fumonisin concentrations were quantified by means of High Performance Liquid
Chromatography (HPLC). Results indicated high natural infection by fumonisinproducing
Fusarium spp. and fumonisin concentrations in warmer production
areas such as Northern Cape, North West and Free State Provinces. High
fumonisin producing fungal biomass and concomitant fumonisin concentrations
(above 2 ppm in certain localities) quantified in this study, could negatively impact
grain quality and food safety and security due to the potentially harmful effects of
this mycotoxin on humans and animals. These data, together with meteorological
data were used to develop a preliminary model based on the non-linear, 3dimentional
Lorentzian equation (Sigmaplot 10.0). Fusarium colonisation of grain
and fumonisin concentrations were related to prevailing weather conditions during
early post-flowering and dough stage of grain development, respectively. Both
colonisation and fumonisin production were significantly inversely correlated with
mean maximum temperature (r=-0.77 and r=-0.60, respectively) with an optimum
temperature of 30.5°C and minimum relative humidity (r=-0.83 and r=-0.79,
respectively) with an optimum of 49.5 % during these critical growth periods.
Keywords: Fusarium, fumonisins, epidemiology, incidence
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