Activity of natural compounds on Fusarium verticillioides and fumonisin production in stored maize kernels

The ability of trans-2-hexenal, carvacrol and eugenol to control F. verticillioides was explored in vitro and in artificially infected kernels. The effect of the trans-2-hexenal fumigation on F. verticillioides control, fumonisin production and kernel germination was also investigated in naturally infected kernels. Trans-2-hexenal, carvacrol and eugenol vapour showed fungicidal activity against F. verticillioides, in in vitro trials. Trans-2-hexenal was the best pathogen inhibitor, followed by carvacrol and eugenol. In maize kernels, fumigations with trans-2-hexenal provided a high inhibitory effect on F. verticillioides growth and its efficacy depended on concentration and time of incubation. The most effective dose of trans-2-hexenal was 369 μL/L, but this concentration induced off-odour in maize. The exposure to 246 μL/L trans-2-hexenal provided the best control of F. verticillioides and no phytotoxic symptoms or off-odour in kernels was observed. In contrast trans-2-hexenal fumigations were ineffective in the reduction of fumonisin concentration and high concentration (369 μL/L) stimulated fumonisin levels. Reduction or delay in the germinability of the kernel was observed after trans-2-hexenal exposure. The results showed that trans-2-hexenal postharvest fumigation is effective in F. verticillioides control also in asymptomatic maize kernels, but cannot reduce fumonisin production.