LEI Feibin, WANG Hancheng, DAI Yuanfeng, ZHANG Chuanqing. Sensitivity baseline to boscalid of Alternaria alternata causing tobacco brown spot in Guizhou Province[J]. Chinese Journal of Pesticide Science, 2021, 23(4): 812-816. DOI: 10.16801/j.issn.1008-7303.2021.0064
    Citation: LEI Feibin, WANG Hancheng, DAI Yuanfeng, ZHANG Chuanqing. Sensitivity baseline to boscalid of Alternaria alternata causing tobacco brown spot in Guizhou Province[J]. Chinese Journal of Pesticide Science, 2021, 23(4): 812-816. DOI: 10.16801/j.issn.1008-7303.2021.0064

    Sensitivity baseline to boscalid of Alternaria alternata causing tobacco brown spot in Guizhou Province

    • The pathogenic fungus causing tobacco brown spot in Guizhou Province was isolated and identified from diseased samples collected during 2014 to 2015, which have never been treated with succinate dehydrogenase inhibitors(SDHIs), and their sensitivity baseline to boscalid was established by mycelial growth rate tests. The results suggested that there were significant differences in colony and conidium morphlogy, and pathogencicity among these isolates. However, all isolates were identified as Alternaria alternata. In addition, the EC50 values of boscalid inhibiting the growth of A. alternata population (n = 102) from tobacco fitted unimodal distribution and varied from 0.186 to 5.818 μg/mL with the mean value of (2.157 ± 1.112) μg/mL, which could be adopted as the baseline sensitivity of A. alternata on tobacco to boscalid and used for monitoring the sensitivity shift in future. Further study indicated that there was some nucleotide polymorphism in codons, such as 209, 277 and 224 in Sdh B of A. alternata. However, no relationship was observed between this nucleotide diversity and the sensitivity to boscalid in A. alternata causing tobacco brown spot.
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