By growth rate method,the inhibitory effects of five solvent extracts from Helianthus tuberosus leaves against Phytophthora capsici were studied in the test.The results showed that different solvent extracts all had inhibitory effect against P.capsici,while 12.5mg/mL of extracts from H.tuberosusleaves with petroleum ether and ethyl acetate as solvents had the highest inhibitory effect against P.capsici,reaching 100%.In case of various solvent extracts with different concentration gradients,ethyl acetate extract had the most significant inhibitory effect;when the concentration was 5mg/mL,the inhibitory effect of ethyl acetate extract had reached 100%;when the concentration reduced to 2.5mg/mL,the inhibitory effect was still(27.91±2.076)%,significantly higher than that of other solvent extracts at the same concentration.The 50 times dilution of ethyl acetate extract fromH.tuberosusleaves was selected for pot test against pepper blight.,and the results showed that its control effect against pepper blight reached 100.00%,superior than that of chemical agent 25% metalaxyl WP 400 times dilution.
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