关键词: 魔芋腐烂病, 分离频率, 症状, 发病率, 致病性

Abstract: In order to clarify the types of Amorphaphallus konjac rot disease and the casual pathogens in Shiyan city of Hubei province, the symptoms of A. konjac rot disease in Shiyan city were investigated, the isolation frequency of each kind of bacteria was determined as well as the classification and pathogenicity of the dominant bacteria. The results showed that the disease incidence and symptoms varied with field sites. The disease symptoms were classified into six types containing circle soft rot on stem base, yellowing and stem base black rot, yellowing and stem split and black, yellowing and stem dry soft, yellowing and external stem base black while interior red, upper stem and whole plant black rot. The most serious disease occurred at Liubei, and the incidences of the first two types of A. konjac rot disease were 13.0% and 26.9%, respectively, and the lowest disease incidence was 4.8% at Yunxi county. Two kinds of fungi, Sclerotium rolfsii and Fusarium sp., and 11 kinds of bacterial strains were isolated from 28 A. konjac samples. The three dominant bacterial isolates were Pectobacterium carotovorum subsp. carotovorum, Stenotrophomonas maltophilia and Klebsiella oxytoca with high isolation frequency of 27.6%, 17.6% and 12.1%, respectively. Pathogenic test indicated that Pectobacterium carotovorum subsp. carotovorum was pathogenic to A. konjac, and specific DNA band was only amplified from the total DNA of isolates B12, B16 and B17. In a conclusion, complex infection was found in A. konjac rot disease, and P. carotovorum subsp. carotovorum was the important pathogen. These results were valuable for the management of A. konjac rot disease.

Key words: Amorphaphallus konjac rot, isolation frequency, disease symptom, disease incidence, pathogens