AUTHOR=Liang Fang , Jiang Xuejing , Liu Lijuan , Wang Feihu , Liu Feng , Hu Saixue , Tan Lijun , Chen Xiao , Xu Yixuan , Xu Xiulan , Jiang Liqiong , Liu Yinggao , Yang Chunlin 

TITLE=White root rot of Bletilla striata: the pathogen, biological characterization, and fungicide screening

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 15 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1374137

DOI=10.3389/fmicb.2024.1374137

ISSN=1664-302X

ABSTRACT=Bletilla striata is an endangered traditional medicinal herb in China. In May 2020, the emergence of white root rot severely impacted the quality and yield of B. striata, affecting about 5% of the plants at plant nurseries of the Chengdu Academy of Agricultural and Forestry Sciences. Through morphological measurement, pathogenicity test, and phylogenetic assessment, the causal agent was identified as Fusarium solani, which is the first report of B. striata white root rot caused by F. solani in Sichuan, China. The effects of different carbon and nitrogen sources, temperatures, photoperiods, and pH values on mycelial growth and sporulation were investigated to inform future disease control. Sucrose was the optimum carbon source for the pathogen, and the optimum temperature and pH for mycelial growth and sporulation were 25℃ and pH 7, respectively, while light had no significant effect. Effective fungicides were screened, among which difenoconazole showed the strongest inhibition with EC50 of 142.773 µg/mL. The optimum fungicide concentration scheme (difenoconazole, pyraclostrobin, and thiophanate-methyl at 395.42, 781.03, and 561.11 µg/mL, respectively) was obtained using response surface methodology (RSM) to improve the inhibition rate of 92.24 ± 0.34%. This study provides basic data for the pathogen characterization of B. striata white root rot and its potential fungicides in Sichuan, China. In addition, the optimal fungicide concentration ratios were obtained through response surface methodology (RSM) optimization, which significantly enhanced the fungicidal effect and provided a scientific basis for the future control of B. striata white root rot.