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Abstract Abstract：In recent years，the‘ black stalk disease’，a new symptom of radish，had become increasinglyserious in Tianjin．The purpose of this study was to accurately identify the pathogen，and carry out fungicidetoxicity test in lab for screening of high efficiency，low toxicity fungicide in the light of target pathogens．Inthis study，the occurrence of radish ‘black stalk’ in the field in Tianjin was investigated．The pathogen was identified by morphological，pathogenicity and molecular biology．Nineteen kinds of fungicides commonly usedfor bacterial control were selected for screening by the inhibition comparison and toxicity testing．The resultsshowed that the pathogenic bacteria causing the‘ black stem disease’ of local Weiqing radish were Xanthomonascampestris pv. campestris（Pam.）Dawson，which was a new symptom of radish black rot disease．Theisolated pathogenic strains exhibited pathogenicity differentiation，among which the highly pathogenic strainLB-B was selected．The results of laboratory toxicity test showed that there were 10 kinds of fungicides withdifferent effects of inhibition on radish black rot．Among them，0.3% tetramycin AS and 10% propylthiazole SChad the best inhibition effect on radish black rot，and their inhibition rates were above 89.52% at 1 000 mg · L-1concentration．The EC50 of 0.3% tetramycin AS and 10% propylthiazole SC were 156.69 mg · L-1 and 174.04mg · L-1，respectively，which showed the stable and the long duration of efficacy in the field．The aboveexperimental results provided candidate fungicide for effective control of radish black rot disease．
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Received: 12 May 2023
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