Bioassay Screening Of Medicinal Herbs Extracts Against Phytophthora Parasitica Var.Nicotianae

In order to screen anti tobacco black shank plant active substance right, this paper using mycelial growth rate method, biometric technology, extract with 5% ethanol solution, calculation of black shank diameter fell, to 45 anti tobacco black shank plant active substance of indoor biological activity determination, the results show that the soil, Rhizoma Coptidis Brevisepalae,Phellodendri Chinensis Cortex,Dioscorea bulbifera L,Magnoliae Officinalis Codex and Peucedani Radix 18 Chinese medicinal materials extract 50 times solution have significant effect, hogfennel root, Schizonepeta, d.bulbifera gentian, Polygonum cuspidatum extract of 11 Chinese medicinal materials 500 times solution have significant effect, which, to kill bacteria mixed best, soaking time, spray sterilization effect is the worst. The pot experiment, the control effect against tobacco black shank plant active substances showed that the plant height, stem diameter, leaf number, Ye Kuan and other agronomical characters and leaf chlorophyll content did not significantly affect plant extracts treatments (Morinda excepted) has a control effect, some of the tobacco black shank the chemical agent (CK), there were significant differences in soil fungi quantity of Coptis; each treatment was lower than that of water (application); Rhizoma Coptidis Brevisepalae,Phellodendri Chinensis Cortex etc were had significant difference.Therefore, this study suggests that extracts from 18 medicinal plants of Rhizoma Coptidis Brevisepalae,Phellodendri Chinensis Cortex,Dioscorea bulbifera L,Magnoliae Officinalis Codex and Peucedani Radix etc 50 times solution of sterilization methods have significant effect on restraining the black shank, wherein the chemical carbendazim, Coptis, phellodendron, d.bulbifera soil has significant control effect on tobacco black shank disease field pot; application of chemical reagents and medicinal plant extract, plant height, stem diameter, leaf number, Ye Kuan and other agronomical characters and chlorophyll and plant disease resistance have a significant influence, have certain relation to the incidence of tobacco plants and soil fungi, soil, phellodendron, Coptis chinensis d.bulbifera etc. medicinal plant extracts may be inhibited by the number of fungi in the soil to prevent the growth of black shank hazards of tobacco plants, the results for tobacco black shank plant source Preparation of the development of technical support.