Isolation, Identification And Biological Characteristics And Pathogenicity Of Pathogenic Fungi

Chenopodium album, as one of the malignant weed in the world, widely distribute in China.Due to the developed root system and extremely exuberant vitality of Chenopodium, thereforeChenopodium album often grows faster than crops and its height is usually over some crops.Chenopodium album not only affects the crop photosynthesis and interferes with the crop growth,but also severely affects crop yield and quality. Chemical control is currently a major method forcontrolling Chenopodium. In recent years, with the wide application of chemical herbicides, aseries of environmental problems are frequently emerging such as the rise of weed resistance anddestroy of ecological balance. How to reduce the use of chemical herbicides has become a urgentproblem faced to us. To develop microbial herbicides is considered as one of the effective waysto solve those problems. The strain Hf-01and the strain Hf-05, two strains with strongpathogenicity to Chenopodium album, were isolated for the infected plant of Chenopodiumalbum. Two strains were identified by method of morphology and molecular biology. Thebiological characteristics of strains, host range of strains and impact factor of strainspathogenicity were also studied in the paper. the main research results are as follows：1. The results from the virulence test of22pathogen strains isolated from diseasedChenopodium album showed that virulence of Hf-01and Hf-05is stronger than that of other.2. Hf-01and Hf-05were be identified as fungus of Phoma spp and Fusarium spp bymorphology method and ITS analysis.3. The result of host range test of the pathogenic strains showed that Chenopodium album andSolanum nigrum was sensitive to strain Hf-01, but wheat, corn, beans and kidney beans were notinfected by strain Hf-01. The strain Hf-05showed a strong virulence to Chenopodium, Setariaviridis, Chloris virgata, Setaria glauca and Echinochloa crusgalli, but Hf-05could not infectbeans, kidney beans, sunflower red beans, kidney beans and sunflower.4. The optimum carbon and nitrogen sources of strain Hf-01are starch and peptone. Theoptimum temperature of mycelium growth was25℃, and the optimum pH of Hf-01growth was6. Light had no significant effect on the growth of Hf-01. The optimum carbon source of strainHf-05is maltose. It was most easily for Hf-05to produce spores in maltose. The optimumnitrogen source of Hf-05was sodium nitrate. The strain Hf-05had a fastest growth rates andhighest spore germination rates under pH8. The most suitable growth temperature of Hf-05was25℃. The optimum temperature of spore germination was30℃. Dark condition was moreconducive to the strain Hf-05growth.5. The result on the pathogenicity of the strains indicated that Chenopodium album was sensitive to Hf-01and Hf-05when Chenopodium album seedling was during two leaves stage tofour leaves stage. The pathogenicity of Hf-01and Hf-05was closely correlated with moisturizingtime. With increasing inoculation doses of Hf-01and Hf-05, fresh weight inhibition rate ofChenopodium album was increased gradually.