Identification of the pathogen of pear valsa canker and screening of chemical fungicide against it
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    Abstract:

    To identify the pathogen of pear valsa canker, the diseased branches of pear tree were collected from the fields of Hebei, Shanxi and Anhui Province respectively in China. Patthogens were isolated from the skin of these branches and then were cultured on PDA medium and purified by single spore culture. Identification of the pathogenic fungus was carried out according to the characteristics of fungal morphology, pathogenicity and sequence analysis of ribosomal DNA internal transcribed spacer (Rdn-ITS). Twenty two chemical fungicides were used to test their antibacterial effect on the mycelium growth and conidiophores germination in vitro and the control effect of the disease in the field by diseased spot cure. The results show that the five strains of purified pathogenic fungus from the six isolates were identical and the same to the reported pathogen Valsa mali var. pyri according to fungal morphologic characteristics. The symptoms induced by artificial inoculation with the five strains were the same as that found in the field. The five strains belonged to the same pathogen by analysis of rDNA-ITS sequence and had been submitted to the National Center for Biotechnology Information (NCBI) with the accession number JQ618018, which had 100% similarity to V.ceratosperma from pear tree in Italy (DQ241769), Valsa mali var.pyri from pear tree in Shanxi (GU174590) and V.ambiens from pear tree in Xinjiang (HM013819) in the database of NCBI. Furthermore, another isolated strain was homologous up to 99% with Paraconiothyrium brasiliense, a kind of plant endophyte by analysis of rDNA-ITS sequence. In the fungicide in vitro assay, there were eight fungicides efficient to suppress the mycelia growth, and eleven fungicides efficient to inhibit the conidium germination. The field tests revealed that the 25% emulsifiable concentrate of Prochloraz in dilution of 1500 times, 20% suspension concentrate of Coumoxystrobin in dilution of 165 times and 97% Azoxystrobin technical in dilution of 15000 times were the most appropriate fungicides. Therefore, it was confirmed that the pathogen of pear valsa canker isolated from the three provinces above was Valsa mali var. pyri and Prochloraz, Coumoxystrobin and Azoxystrobin were high efficient chemicals in control of pear valsa canker in the production.

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叶振风,吴湘琴,吕冠华,薛程,吴婷婷,刘普,朱立武. Identification of the pathogen of pear valsa canker and screening of chemical fungicide against it[J]. Jorunal of Huazhong Agricultural University,2015,34(2):49-55.

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  • Received:
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  • Online: January 30,2015
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