Abstract: JS399-19 (2-cyano-3-amino-3-phenylacrylic acetate) is a novel fungicide exhibiting specific activity against Fusarium graminearum.In vitro,the inhibitory activity of the fungicide against mycelial growth of both sensitive and resistant isolates of Fusarium graminearum was measured and the influence of the fungicide on conidial germination of Fusasium graminearum was determined.The results showed that JS399-19 could strongly inhibit the mycelial growth of a sensitive isolate of Fusarium graminearum with the EC50 values 0.092~0.141 μg/mL.JS399-19 decreased the speed of conidial germination of the sensitive isolate of Fusarium graminearum,strongly inhibited the germtube growth of the conidia,and affected the conidia germination by increasing the ratio of the tubes germinated from the basal and that from the middle parts of the conidia increased.Moreover,JS399-19 could cause abnormality of conidia and the tubes of the sensitive isolate,by inducing the conidia,and the tubes swollen and contort,respectively.However,the fungicide weakly affected the JS399-19-resistant isolates.