Abstract: To clarify the causal agent of leaf blight on Curcuma wenyujin in Guangxi, identify the pathogenic species, analyze its biological characteristics, and evaluate the efficacy of common fungicides, the pathogen was isolated via the tissue isolation method. Species identification was conducted through pathogenicity tests, morphological observation, and multi-gene sequence analysis of ITS, TEF1, H3, and TUB2. The effects of different media, temperature, pH, light, and carbon/nitrogen sources on mycelial growth were determined using the mycelial growth rate method. The indoor toxicity of four fungicides was tested using the fungicide-amended plate method. A total of 38 strains were isolated and purified from diseased leaf tissues. The 27 strains with the highest isolation frequency (71.05%) and consistent morphology were selected as representative strains and designated JH43-2 for subsequent studies. Morphological and multi-gene phylogenetic analyses identified strain JH43-2 as Diaporthe ueckeri. The fungus grew optimally at 20-30 ℃, tolerated pH 5-9, and utilized various carbon and nitrogen sources, with the most vigorous mycelial growth observed when inositol was used as the carbon source and sodium nitrate as the nitrogen source. Toxicity assays showed that the tested agents—Trichoderma harzianum, hymexazol, pyraclostrobin, and prochloraz—all inhibited the pathogen, with Trichoderma harzianum exhibiting the strongest effect (EC₅₀= 0.019 6 mg/L).

Key words: Curcuma wenyujin leaf blight, Diaporthe ueckeri, biological characteristics, toxicity assay, fungicide screening