Inhibition Activities Of The Extracts From The Plants Of Artemisia Argyi To Phytopathogeic Fungi

In this paper, the antifungal activities of the extracts of Artemisia argyi Levl.et Vant to phytopathogen were systematically studied. The sensitivity strains, extracting conditions, the virulence and the physical and chemical characters were investigated. The toxicology and controlling effects on Rhizoctonia solania were mainly detected. Results are summarized as follows:The extract of Artemisia by ethanol had bioactivity on the13 kinds of tested fungi. When the concentration is 50 mg·mL^-1 , it could inhibit the hypha growth of Rhizoctonia solania, Sclerotinia sclerotiorum more than 90%, and 70～86% inhibiting rates to Phytophthra capsisi, Peronophythora litchii, Penicillium digitatum, Botrytis cinerea. Furthermore, the extract had more than 90% inhibiting rates to the spores germination of Fusarium oxysporum, Fusarium oxysporum f.sp.cubense, Colletotrichum musae, Pyricularia grisea, Botrytis cinerea. By observation of morphological character, it shows, while inoculated in the substrate with extract, the mycelia would be abnormity growth such as contort, bulging, vacuole increasing, more branches, and the space between branches been shortened, ect..It is indicated that the superiority order of extract solvent was CH₃COOC₂H₅, C₂H₅OH, CH₃COCH₃, CHCl₃, petroleum ether and H₂O, the extract of solvent CH₃COOC₂H₅ had the best bioactivities, it can completely inhibit the hypha growth of Phytophthra capsisi, Sclerotinia sclerotiorum, Peronophythora litchi, and the inhibiting rates to Rhizoctonia solania was 96．0%.The plant got before abloom had more superiority bioactivity than other periods,and the inhibiting ability of its leaves was preponderant than the stems. By detecting the inhibiting rates of sequence extracts, it shows that the active ingredients were collected in solvent of ethyl acetate and chloroform.By detecting the toxicity to the tested strains, it shows that the superiority toxicity order of extract of solvent ethyl acetate to inhibit the hypha growth were Colletotrichum musae,Sclerotinia sclerotiorum, Fusarium oxysporum f.sp.cubense, Phytophthra capsisi, with EC₅₀ 10．66～16．73 mg·mL_-1 ,and the superiority order inhibitting spore germination were Pyricularia grisea, Fusarium oxysporum f.sp.cubense, Alternaria brassicae, with EC₅₀ 2．52,3．67,4．64 mg·mL^-1 . The superiority toxicity order of extract of solvent ethyl acetate inhibitting the hypha growth were Phytophthra capsisi, Colletotrichum musae, Fusarium oxysporum f.sp.cubense, with EC₅₀ 19．045～44．55 mg·mL^-1 .The active ingredients have stable chemistry properties. The inhibiting rates can be kept while the extract being heated, ultraviolet radiated and long time stored. The extract of solvent ethanol was further separated with some solvent or aqueous solution in sequence pH value, and it shows that the active ingredients were in the subsection of solvent of ethyl acetate petroleum ether or Na₂CO₃(aq), neutral oil. The FT-IR indicates that the phenolic group in the weak acid oil subsection and carbonyl group exist in the neutral oil subsection.The extract by solvent ethanol has excelent activities in habiting the hypha growth and restrain forming sclerotiumia on Rhizoctonia solania, with EC₅₀ 5．85(48 h) and 14．00 mg·mL_-1 respectively。The studies on toxicology and controlling effects of the extract by solvent ethanol shows it can restrain respiration, damage the cell membrane and result in the cell permeability promoting, and the inclusion seepage enhancing. It was found that more extracellular cellulose enzyme and reducing sugar dissolved, with the raising of the dose of the drug. This resulted in the mycelium mass lost and the conductance of the mycelium suspension changed. The tests also proved that the extract had systemic action to Rhizoctonia solania. For all of above, the mycelium were lead to abnormity growth, even to death. Finally, the bioassay on leaves proved that the extract had 90．3% protective efficacy and 36．4% cure efficacy to the Rhizoctonia solania under the concentration of 100 mg·mL^-1 .The study shows that the active ingredients of Artemisia argyi has the great potential to be developed as a new Botanic fungicide.