Effect of Fungicides on Sclerotia of Aflatoxigenic Aspergillus flavus

Abstract

The opportunistic pathogen Aspergillus flavus infects a vast range of agricultural crops and products, before and during harvest, handling, shipment and storage and can produce aflatoxins out of which Aflatoxin B1 was classified as group I human carcinogens by International Agency for Research on Cancer. This mitotic fungus produces sclerotia which can resist unfavourable environmental conditions by remaining dormant for long periods and may contain a considerable quantity of aflatoxins. Subsequently, sclerotia possess threat to contaminate the food chain and spreading of infection by adhering to crops in the field or during transportation. Thus suitable fungicides need to be explored for the management of sclerotia and Aspergillus flavus. Hence in the current investigation, the effect of three commercial fungicides indicated as CD, MZ and CH having active compositions Carbendazim 50%, Mancozeb 75% and Copper Hydroxide 77% respectively, was tested on sclerotia of aflatoxigenic Aspergillus flavus and the subsequent inhibition of mycelia growth and aflatoxin production was observed for two generations. Variation in colony characteristics could not be observed in either generation. Carbendazim and Mancozeb were found better than Copper Hydroxide fungicide for the inhibition of the germination of sclerotia but Mancozeb inhibited mycelia growth. Carbendazim and Copper Hydroxide had reduced the ability of the fungus to produce aflatoxin B1 whereas Mancozeb elevated the aflatoxin B1 production in the first generation. A. flavus cultures had no difference in Aflatoxin production in the second generation. Both mycelia growth and aflatoxin B1 production could not be inhibited by the same fungicide used in this study. Considering the deleterious effect of aflatoxins on human, animal health and agriculture, strategies need to be devised for the careful selection of fungicides to control Aspergillus flavus.