From 2020 to 2023, two foliar diseases suspected to be curvularia
leaf spot and anthracnose were found on tobacco in Chenzhou City, Hunan Province. The objective of this study was to clarify the pathogens and provide theoretical reference for scientific and effective control of the diseases. The fungal pathogens were isolated from symptomatic leaves by tissue isolation and the diseases were identified to be leaf spot and anthracnose by both morphological observation and Koch's postulates. Combined with the morphological characteristics and ITS based phylogenetic analysis, the pathogen of the tobacco leaf spot was determined to be Curvularia trifolii
, while the pathogen of the tobacco anthracnose was identified as Colletotrichum karstii
using both the morphological and molecular characteristics by ITS, ACT
gene regions. The study of biological characteristics showed that the optimum temperature for mycelium growth of C. trifolii
was 25℃, the optimum pH was 7, and it was most favorable for mycelium growth when soluble starch was used as carbon source and beef powder as nitrogen source. The optimum temperature for mycelium growth of C. karstii
was 25℃, the optimum pH was 7, and it was most favorable for mycelium growth when glucose was used as carbon source and beef powder as nitrogen source. To our knowledge, this is the first time that these two diseases are reported in Hunan Province of China. Up to now, there is no report of C. karstii
causing disease in flue-cured tobacco in China. The results can provide a basis for the scientific and effective prevention and control of these diseases.