Preliminary Study On Biocontrol Of The Alternaria Alternata Keissl

Poplar is the species which are widely distributed in the world,adaptable and mainly in northern temperate,cold temperate regions. Poplar not only can check winds but also can fix drifting sand,conserve soil and water,improve the environment,and its wood is fine material in manufacturing fibreboard,particle board,block board and paper pulp with high social, ecological and economic benefits,it is very popular in China.Poplar is also a species pest occurred more,poplar leaf blight disease is one of the main disease which has a serious impact on many aspects of poplar benefits.This research is to separate the pathogen of poplar leaf blight,Strain was identified as fungi imperfecti,Trichosporon Gang,Trichosporon fungi present,Fine tenuis by microscopic morphology and molecular identification, rDNA-ITS sequencing results showed that the homology of GenBank is greater than 99%.This paper studied the community structure of Poplar fungi of needles,morphological and molecular biology methods were used for identification of fungi,and use the isolated fungi selected antagonistic strains,take such leaves grouped joint test and select biocontrol bacteria with high value of prevention.Isolated from the poplar leaves,we can get 1 ascomycetes genera,15 mitosis bacteria genera,these are not specifically identified to species. Some are only numbered. Among the 15 mitosis,bacteria,genera,including:Gliocladium,Graphium,Cladosporium,Coniothyrium,Curvula ria,Paecilomyces,Epicoccum,Mortierella,Aspergillus,Penicillium,Fusarium,Trichoderma,Gilm aniella,Tolura,Verticilium and the genera of Ascomycota:Chaetomium.According to growth radius of antagonism,the inhibition rate of pathogenic bacteria,the relative inhibitory effect and the comprehensive evaluation of anti-parasitic in the late period of bacteria,It is determined that the antagonistic strains can inhibited the pathogen of poplar leaf blight disease effectively,and then selected Trichoderma,Chaetomium,Tolura as experimental biocontrol strains. Meawhile Tolura is saprophytic bacteria,the antagonistic experiments show that we can inhibit the alternaria tenuis of polar and prevent it from growing.Inoculation tests showed that,in addition to the leaves of inoculated pathogen Alternaria alternata isolated from pathogens,the rest of inoculated leaves isolated nothing from it. It showed that Description T. atroviride,C. globosum and T. herbarum, this three strains has good inhibition to Alternaria alternata which is pathogenic bacteria of poplar leaf blight disease. The biocontrol experiments of concentration gradient show that control effect is the T. herbarum> mancozeb 400 dilution> T. atroviride> C. globosum, when the three kinds of microbial agents is in the spray concentration of 50%,the diversity of fungi is maximum,and it is most similar to the control group of CK. It indicates that the concentration of leaf fungi system is more stable than other concentrations on this concentration.