Welcome to Chinese Journal of Tropical Crops,

Chinese Journal of Tropical Crops ›› 2022, Vol. 43 ›› Issue (12): 2534-2544.DOI: 10.3969/j.issn.1000-2561.2022.12.016

• Plant Protection & Bio-safety • Previous Articles     Next Articles

Identification, Biological Characteristics and Fungicide Screening of Tobacco Leaf Spot Disease Pathogen Epicoccum latusicollum

AN Xuanxian1, SANG Weijun1,*(), LU Yanhui2, KONG Fei2, WANG Wuquan2,*(), LI Haoxi1, YANG Jiangmin1, PENG Lijuan1, YANG Maofa1   

  1. 1. College of Tobacco Science, Guizhou University / Guizhou Provincial Key Laboratory for Tobacco Quality Research, Guiyang, Guizhou 550025, China
    2. Department of Science and Technology, Guangxi Zhuang Autonomous Region Company, China National Tobacco Corporation, Nanning, Guangxi 530022, China
  • Received:2022-05-10 Revised:2022-06-14 Online:2022-12-25 Published:2023-01-12
  • Contact: SANG Weijun,WANG Wuquan


Leaf spot disease is one of the main tobacco diseases in the field period, which is mainly caused by fungal infection. It is easy to happen and spread, and has a great impact on the quality and yield of tobacco. In this study, the strain was isolated and purified from the leaves with typical leaf spot diseases of tobacco variety ‘K326’ in Guangxi Zhuang Autonomous Region by tissue separation, and through pathogenicity determination combined with morphological characteristics and molecular biological methods to identify pathogens. The mycelium growth rate method was used to measure the mycelium growth of pathogens in different media, temperature, pH, carbon source, nitrogen source, light, lethal temperature treatment and 10 common chemical conditions. In the early period of tobacco leaf spot disease, the typical symptoms of the leaf spot disease are gray white small round spots. As the disease worsens, the round spot gradually diffuses into irregular shape, and the center of the spot forms a perforation, the color is gray white, the edge is brown, and accompanied by a yellow halo. We isolated and purified two strains and named them as HZFC36 and HZZS76. The pathogenicity test results showed that both strains could cause disease spots on the leaves of healthy ‘K326’ tobacco plant under the condition of no leaf injury. Epicoccum latusicollum was identified as the pathogen causing tobacco leaf spot disease in Guangxi, based on morphological characteristics of pathogen and phylogenetic analysis of multiple loci (LSU, ITS, RPB2 and TUB2). The mycelia of the pathogen grew the fastest on CMA medium, and the optimal growth temperature was 28℃, the optimal pH was 6, the optimal carbon was sucrose and nitrogen source was beef extract powder. 24 h continuous light is favorable to the growth of the mycelia, and the mycelia did not grow after being continuously treated in water bath at 47℃ for 10 min. Preliminary screening results of chemical fungicides in the laboratory showed that 50% boscalid and 25% pyraclostrobine had the best inhibitory effect on the pathogen with EC50 value 4.752×10-2 mg/L and 4.989×10-2 mg/L respectively. The results of the study would provide a theoretical basis for the field control of tobacco leaf spot caused by E. latusicollum.

Key words: leaf spot disease, identification of pathogenic bacteria, biological characteristics, fungicide screening

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