| Valsa canker is one of the main diseases impairing ornamental value.To date,the identification of the pathogen causing the disease of ornamental crabapple in China had never carried out.Ornamental crabapple is also from the last 20 years before the introduction of a large number of our country,the introduction of the disease resistance in China is consistent with the origin is not clear.This research has been the pathogen of ornamental crabapple valsa canker related by tissue isolation method,identified by the methods of morphology and molecular biology,the disease resistance of some ornamental crabapple varieties and application discussion in Beijing were tested,the results are as follows:1?The isolates were divided into 2 groups according to the morphological characteristics and rDNA-ITS sequences.The isolates were identified as one group: Valsa mali.2?The pathogenicity of the isolates could be caused by the occurrence of ornamental crabapple branches,the pathogenicity of the strains was very strong,and the susceptibility index of the 2 groups were 96.67 and 94.44.The results showed that V.mali was the pathogen causing the valsa canker of ornamental crabapple,the total isolation rate was 76.79%,which was the dominant strain.3?The test results are as follows.Better resistance germplasm: Malus ‘Prairifire' Malus‘Jewelberry',Malus ‘Indian Magic';Medium resistance germplasm: Malus ‘Red Splendor',Malus ‘Sargentii',Malus ‘Professor Sprenger',Malus ‘Flame',Malus ‘Adirondack',Malus‘Lemonei',Malus ‘Robinson',Malus ‘Liset',Malus ‘Eleyi',Malus ‘Sparkler';Weak resistance germplasm: Malus ‘Evereste',Malus ‘Golden Hornet',Malus ‘Red Sentinel',Malus ‘Neville Copeman',Malus ‘Hope',Malus ‘Coralburst',Malus ‘Red Sentinel',Malus ‘Makamik';Poor resistance germplasm: Malus ‘Van Esseltine',Malus ‘Butterball';Especially poor resistance germplasm: nothing.4?The application mode of high resistance and medium resistance crabapple varieties was discussed,and the application ideas were provided. |
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