Control Of Grape Downy Mildew With The Extracts Of Chinese Medicinal Plants

Up to now,the main control measure of grape downy mildew is the application of chemical fungicides,which not only pollutes the environment,but also results in fungicide resistance of Plasmopara viticola.In order to explore the safe and efficient biological control methods on grape downy mildew,develop new plant fungicides,lay the foundation for better control of grape downy mildew,and provide new research ideas for the control of the disease,eighty kinds of Chinese medicinal plants were selected as the research objects in this study for screening Chinese medicinal plants with better control effect on grape downy mildew.Water and ethanol extraction methods were used to extract,respectively,and control bioassays in growth chamber and field control tests were performed to detect the control effects of Chinese medicinal plant extracts with strong inhibitive activities against P.viticola.Based on the above results,the control effects of the water extract from the most effective Chinese medicinal plant Foeniculum vulgare on P.viticola from different regions were determined,and the active substances in water extract of F.vulgare were analyzed using high performance liquid chromatography(HPLC).The main results were as following.The results from screening tests of the water extract of Chinese herbal medicinal plants showed that the water extracts of F.vulgare,Cuminum cyminum and Polygala tenuifolia had good inhibition effects on sporangial germination in P.viticola,which were 56.0%,42.6%and 37.5%,respectively.The results from biological control tests in growth chamber showed that the water extracts of nine Chinese herbal medicinal plants,including F.vulgare,Eucommia ulmoides and Schisandra chinensis had good control effects,which were 78.9%,76.3%and 73.7%,respectively.In the field control experiments,the water extracts of F.vulgare、E.ulmoides and P.tenuifolia had a good field control effect on grape downy mildew with control efficacies of 48.2%,47.5%and 44.6%,respectively.The results from biological control tests in growth chamber with the ethanol extracts of Chinese medicinal plants showed that Syzygium aromaticum and Dryopteris crassirhizoma had good control effects on grape downy mildew,which were 66.7%and 62.5%,respectively.In the field control experiments,the effects of ethanol extract from D.crassirhizoma,Viola philippica and Pulsatilla chinensis were the best,with control efficacies of 36.0%,29.3%and 24.8%,respectively.The water extract of F.vulgare showed the best inhibitory effect on sporangial germination of P.viticola from Baoding of Hebei Province,reaching 56.0%,followed by Liaocheng of Shandong Province,Shenyang of Liaoning Province and Zhuzhou of Hunan Province,with control efficacies of 30.8%,26.7%and 18.7%,respectively.The water extract of F.vulgare showed the best control effect on grape downy mildew caused by P.viticola in Baoding of Hebei,reaching 60.0%,followed by Liaocheng of Shandong,Shenyang of Liaoning,Zhuzhou of Hunan and Zhengzhou of Henan,which were 40.0%、25.0%、21.7%and 17.3%.The inhibition rates on sporangial germination in P.viticola of the two F.vulgare water extracts obtained from extracting conditions of 45℃ and 25℃ were 33.5%and 32.2%,respectively,with no significant difference.The result from HPLC analysis showed that quercetin in the water extract of F.vulgare is the active compound.