3-Acetyl deoxynivalenol production in a strain ofFusarium culmorum insensitive to the fungicide difenoconazole.

The production of the mycotoxin, 3-acetyl deoxynivalenol (3-ADON), was investigated in a strain ofFusarium culmorum insensitive to the systemic fungicide, difenoconazole. On exposure to graded concentrations of the fungicide, the insensitive strain continued to synthesise 3-ADON when difenoconazole levels of 100 and 200μg/ ml media were used. In contrast, a control (sensitive) strain ceased production of 3-ADON at difenoconazole levels of 100 μg/ml. Differences between the two strains were also observed for 3-ADON production with time. Following incubation with fungicide at 0.1 μg/ ml, 3-ADON production occurred more rapidly in CS than in IS cultures. This is the first report of increased persistence and alteration of the pattern of production of a mycotoxin following the development of fungicide insensitivity in a fungal phytopathogen.