Morphological,Molecular and Pathogenicity of Alternaria gaisen Associated with Leaf Brown-Spot on‘Gonggan’Mandarin in China

[Objective]This paper was to identify the pathogen of leaf brown-spot on‘gonggan’mandarin(Citrus reticulate var.gonggan)in Zhaoqing,Guangdong Province.[Method]The pathogen was determined based on sequence analysis of ITS,endoPG,tef1,gapdh,Alt a1,rpb2 and opa10-2 genes;the morphological characteristics were recorded on PDA and PCA;and its pathogenicity on excised and intact host leaves of citrus‘gonggan’was tested.[Result]A detailed description of Alternaria gaisen was obtained based on morphological,molecular and pathogenic characterization,which was the causal agent of brown-spot disease on leaves of‘gonggan’mandarin orchard trees in Zhaoqing,Guangdong,China.[Conclusion]This study provides a scientific basis for the effective control of leaf brown-spot on‘gonggan’mandarin.

17种杀菌剂对贡柑炭疽病菌的生物活性测定研究

采用菌丝生长速率法测定了17种杀菌剂对发生于德庆的贡柑炭疽病菌的生物活性。结果表明,参测的12种新杀菌剂中,10种新杀菌剂[250 g/L施保克乳油、50%施保功可湿性粉剂、250 g/L势克乳油、250 g/L凯润乳油、250 g/L必扑尔乳油、300 g/L爱苗乳油、10%世高水分散粒剂、62%霜炭清(B)可湿性粉剂、75 g/L欧宝乳油和250 g/L富力库水乳剂]均对贡柑炭疽病菌表现出优异的抑制作用,EC50值介于0.0128～0.3637μg/mL之间,明显优于参测的250 g/L阿米西达悬浮剂(EC50=14.9902μg/mL)、50%翠贝水分散粒剂(EC50=114.7402μg/mL)和50%多菌灵可湿性粉剂(EC50=8.3998μg/mL)、40%达科宁悬浮剂(EC50=13.2340μg/mL)、62%双博可湿性粉剂(EC50=122.5649μg/mL)等5种常用杀菌剂、80%代森锰锌可湿性粉剂(EC50=400.9587μg/mL)、70%甲基托布津可湿性粉剂(EC50=131904.3068μg/mL)。