Biological control is a modern, comprehensive and non-polluting approach to the management of diseases. Control of plant pathogen by using biological preparations derived from plants like garlic, mint, thyme, grapefruit, has shown attractive and promising results. Present study aimed at laboratory evaluation the properties of ethanol extract of Silphium perfoliatum leaves towards fungi colonizing pepper plants grown in the field. The mycelium of Alternaria alternata, Botrytis cinerea, Colletotrichum coccodes, Fusarium oxysporum, Penicillium expansum, Trichoderma harzianum were used in experiment. The Silphium extract was applied in two concentrations: 5% and 10%. Leaves were obtained from the three-year S. perfoliatum plantation. Tested fungal isolates originated from pepper plants grown in the field. The studies made use of a Petri dishes method recommended for testing fungicides in laboratory conditions. The Silphium extracts in two tested concentrations significantly inhibited the growth of tested fungi species, with the exception of T. harzianum and B. cinerea in 5% concentration extract. Effects of 10% extract were longer than those of 5% one. A. alternata and C. coccodes were fungi, growth of which was the most strongly inhibited by tested concentrations of Silphium extracts.

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