Abstract: Taking natural capsaicin as raw material,the antimicrobial activity of natural capsaicin on seven kinds of phytopathogen （including Colletotrichum gloeosporioides,Cylindrocarpon destructans,Alternaria solani,Botrytis cinerea,Alternaria brassicae,Fusarium graminearum,Fusarium oxysporum） were tested through toxic medium method. The results showed that above-mentioned even kinds of phytopathogen were inhibited growth by natural capsaicin,the order of antimicrobial activity on above-mentioned seven kinds of phytopathogen were Botrytis cinerea>Alternaria brassicae>Colletotrichum gloeosporioides>Alternaria solani>Fusarium oxysporum>Fusarium graminearum>Cylindrocarpon destructan. In certain range,antimicrobial activity of natural capsaicin were positively correlated with concentrations and time,respectively. However,weakening trend of antimicrobial activity appeared when some high concentrations of natural capsaicin and a certain time scale. The natural capsaicin showed up most strongly antimicrobial activity on above-mentioned seven kinds of phytopathogen when phytopathogen were trained for 72 hours on medium with 0.11% natural capsaicin,specially,the antimicrobial activity on B. cinerea was 71.20%.

Key words: natural capsaicin, phytopathogen, antimicrobial activity