Effect of five fungicides on growth and ochratoxin A production by two Aspergillus carbonarius and Aspergillus niger isolated from Moroccan grapes

Five fungicides azoxystrobin (ortiva), benomyl (benlate), hexaconazole (hexa), pyrimethanil (scala) and thiabendazole (tectocal) were tested sepa-rately in vitro for their ability to inhibit the growth of two ochratoxigenic strains of A. niger and A. carbonarius previously isolated from grapes. All fungicides effectively reduced the growth rate of A. carbonarius and A. niger from 34 to 100% at the recommended dose (RD). Thiabendazole caused total inhibition of spore germination and growth of the two strains, regardless of the doses assayed. Benomyl completely inhibited growth of A. niger whereas for A. carbonarius, concentrations above 0.02xRD were required to prevent the growth. The inhibitory effect of hexaconazole, azoxystrobin and pyrime-thanil was dose-dependent. At sub-lethal concentrations of three fungicides, a dose-dependent increase in in ochratoxin A biosynthesis by two strains was observed. The use of fungicide should be checked for its ability to inhibit fungal growth as well as for their effect in terms of mycotoxins biosynthesis.