Studies On Idendifications And Biological Characteristics Of The Major Pathogens Causing Leek Diseases In Liuzhou, Guangxi

In recent years, leek yellow leaf disease broke out in a commercial plantation in Liuzhou, Guangxi, China. The symptom appeared as half or whole of leaves turning yellow. Yellow, mucoid colonies were consistently isolated from infected tissues. The strains reproduced the typical symptom after being inoculated into healthy leaves of leek. The colonies re-isolated from inoculated leaves were as the same as those from naturally infected tissues. The pathogen was preliminarily identified as Erwinia herbicola var. ananas (Serrano) Dye based on bacterial morphological, cultural, physiological and biochemical properties as well as the sequence of 16S ribosomal DNA. Study on biological characteristics of Erwinia herbicola var. ananas (Serrano) Dye causing leek yellow leaf disease was carried out. The results indicated that the pathogen could grow at 16℃-40℃. The optimum temperature for its growth was 24℃-28℃. The pathogen could grow in the media with pH4~9. The optimum pH for its growth was 7. The pathogen could grow on all tested carbon and nitrogen sources.Leek blight broke out in a commercial plantation in Liuzhou too. The disease reduced yield and profits of leek badly. The pathogen causing leek blight was identified as Sclerotium rolfsii Sacc. based on its cultural and morphological characteristics. Study on biological characteristics of Sclerotium rolfsii Sacc. was carried out. The results indicated that the range of temperature for mycelium growth was 13℃-40℃, the optimum at 31℃. The range of pH for its growth...