Study on Combined Inhibitory Effects of Chinese Herb Extracts against Alternaria alternate

Agar plate tests were conducted to test the inhibitory effects in-vitro of Chinese herb extracts such as pyrolin,Coptis chinensis Franch extract,Phellodendron chinense Schneid extract and Magnolia officinalis Rehd extract against Alternaria alternate in order to find the new type natural antisepic agent.Based on linear regression,it was calculated that the 50% of effective concentration(EC50) of these extracts are 0.22,10.19,10.35,0.34 mg/ml respectively.According to EC50,five ratios were determined by six equal-part points of additive action line,and synergism was identified by co-toxicity factor method.The result showed that the extracts of Coptis chinensis Franch and Magnolia officinalis Rehd with the ratio of 25:2 are the best mixture for controlling A.alternate.