Quantitative detection of Fusarium pathogens and their mycotoxins in South African maize

The distribution and co-occurrence of four Fusarium species and their mycotoxins were investigated in maize samples from two susceptible cultivars collected at 14 localities in South Africa during 2008 and 2009. Real-time PCR was used to quantify the respective Fusarium species in maize grain, and mycotoxins were quantified by multi-toxin analysis using HPLC-MS. In 2008, F.similar to graminearum was the predominant species associated with maize ear rot in the eastern Free State, Mpumalanga and KwaZulu-Natal provinces, while F.similar to verticillioides was predominant in the Northwest, the western Free State and the Northern Cape provinces. In 2009, maize ear rot infection was higher and F.similar to graminearum became the predominant species found in the Northwest province. Fusarium subglutinans was associated with maize ear rot in both years at most of the localities, while F.similar to proliferatum was not detected from any of the localities. Type B trichothecenes, especially deoxynivalenol, and zearalenone were well correlated with the amount of F.similar to graminearum, fumonisins with F.similar to verticillioides, and moniliformin and beauvericin with F.similar to subglutinans. This information is of great importance to aid understanding of the distribution and epidemiology of Fusarium species in South Africa, and for predicting mycotoxin contamination risks and implementing preventative disease management strategies.