Plant diseases are a serious problem for agricultural crops, the food industry and human health. Significant efforts have been made in recent years to find natural products that could reduce the growth of plant pathogens and improve food quality. At present, there is an increased interest in plants as a source of biological active compounds that can protect crops from diseases. Important sources of these phytochemicals are lesser-known pseudocereals such as amaranth. The objective of this study was to determine the antifungal activity of leaf extracts of four amaranth species (A. cruentus, A. hypochondriacus × hybridus, A. retroflexus and A. hybridus). The antifungal potency of amaranth extracts was analyzed against selected strains of fungi. The results suggested that the antimicrobial properties of the tested extracts varied depending on the amaranth species and the fungal strain. The studied extracts inhibited the growth of Fusarium equiseti, Rhizoctonia solani, Trichoderma harzianum and Alternaria alternata. A lower inhibitory effect of the extracts was recorded against F. solani, while no inhibitory effect was observed against F. oxysporum and Colletotrichum coccodes.
Keywords: Amaranthus cruentus; Amaranthus hybridus; Amaranthus hypochondriacus × hybridus; Amaranthus retroflexus; fungal diseases; plant extract.