陈潇航, 张小秋, 黄海荣, 宋修鹏, 李文教, 梁永检, 雷敬超, 王泽平, 祝光湖, 刘期怀, 李翔, and 颜梅新
Objective] Studying the pathogenic bacteria of sugarcane brown stripe disease in Guangxi to provide scientific basis for scientific and effective prevention and control of sugarcane brown stripe disease. [Method] Using plant tissue isolation methods, pure cultures of the pathogenic fungus were isolated from diseased sugarcane leaves in Guangxi. Pathogenicity assays, morphological observations, and phylogenetic analysis based on polygenic nucleotides sequences (rDNA-ITS, GAPDH, LSU, EF-1α) were employed to identify the pathogen. Furthermore, the sensitivity of 9 fungicides on the pathogen were also tested in vitro using the mycelial growth rate method. [Result) A pathogenic fungus named GHT-01 was isolated from diseased sugarcane leaves. The fungus isolates were brown or black colonies with sparse white aerial myceli- um. The spores were solitary or clustered, straight or slightly curved, with three septum and four cells, the third cell being larger and darker in color than the others. The size of the conidia was 12.3 -24.1 µm x 5.2-12.8 µm. Multi-locus sequence analysis showed that it clustered with model strain of Curvularia lunata (CBS730.96, CBS157.34). Koch's postulates confirmed that symptoms induced by the pathogen on healthy sugarcane leaves and conidia morphology of the re-isolated fungus matched the initially isolated strain. Therefore, the pathogenic fun- gus was identified as C. lunata. Fungicide sensitivity assays revealed that the best antimicrobial effect was observed with 40% benpyrazyl e- ther emulsion +45% prochloraz emulsion, and their EC50 values were 1.43 and 1.54 µg/mL, respectively. In contrast, the antimicrobial effect of 60% oxazole ether metiram water dispersible granule was less effective, with inhibited medium concentration (EC50) values of 205.82 µg/mL. [Conclusion] The study represents the first identification of C. lunata as the pathogen of brown stripe disease in sugarcane in Guangxi. Additionally, 40% benpyrazyl ether emulsion + 45% prochloraz emulsion are identified as effective fungicides in inhibiting the growth of the pathogen. [ABSTRACT FROM AUTHOR]