In vitro impact on growth, fumonisins and aflatoxins production by Fusarium verticillioides and Aspergillus flavus using anti-fungal compounds and a biological control agent

The temporal efficacy of three different chemical fungicides (Folicur (R), Proline (R), Sportak 45EW (R)) and a biocontrol bacterium (Serenade, B. subtilis) in reducing growth and toxin production by isolates of F. verticillioides and A. flavus was studied in vitro under different water activity regimes (0.99, 0.98 and 0.95). All the fungicides significantly inhibited mycelial growth compared with the control; the most effective treatment, both against F. verticillioides and A. flavus, was Sportak 45EW (R) (approx. 99%). The inhibitory effect of all fungicides generally improved with increasing concentration. Serenade always decreased fungal growth, with optimal results at concentrations of 10(4) and 10(6) (70-75% reduction). All the fungicide treatments resulted in a significant reduction in both FB1 + FB2 and AFB(1) production when compared to the control, at the end of the incubation period and with the 2 concentrations used (approx. 99%). A threshold concentration inoculum of at least 10(4) CFUs of B. subtilis per g was required to achieve a significant control of mycotoxin production. Sportak 45EW (R) and Serenade gave the best control of mycotoxin production with a reduction of 95% compared to the controls. Use of Serenade in the field should include due consideration to its sensitivity to low water activities, when compared to the target pathogens.