Effect of 2 Methods with Low-temperature Preservation on Strains Viability and Pathogenicity of Cytospora chrysosperma

In this study, low-temperature preserved of Cytospora chrysosperma in paraffin oil from 1986s and preserved in test-tube bevel from 2009s, were tested for their viability and pathogenicity.The results showed that the average viability index of C.chrysosperma preserved by paraffin oil was 33.3%, the average viability index of the strain preserved by test-tube bevel was 10.0%.Therefore, the longest preservation time was 29 years by paraffin oil in low-temperature.The test-tube bevel preservation also has a higher survival rate.There were some differences in the pathogenicity of the 2 methods for the preservation of C.chrysosperma.The pathogenicity of the strains of low temperature preservation by paraffin oil were higher than that of test-tube bevel.In the field, the incidence disease of Populus bolleana was up to 40%, while inoculated with strains of low temperature preservation by paraffin oil.