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Simple Summary: The tubers of Gastrodia elata, used in traditional medicine for over two thousand years, are highly susceptible to fungal infections, making tuber rot a common issue during its cultivation. This study investigated a significant outbreak of brown rot disease affecting G. elata f. elata in Hunan Province, China. Typical symptoms include initial brown spots on the tuber surface that expand and darken, with the spots spreading inward and causing the surrounding tissue to transition from brown to black. In this study, the fungal pathogen causing brown rot disease on G. elata was isolated and examined in detail for morphological characteristics, including color, sporulation structures, and spore size. Its identification was further supported by phylogenetic analysis. The findings indicated that the fungal pathogen causing brown rot disease on G. elata f. elata was Clonostachys rosea. Gastrodia elata, commonly known as Tian Ma, is a perennial mycoheterotrophic orchid. Qianyang Tian Ma (QTM), a geographical indication agricultural product from Hongjiang City, Hunan Province, China, is primarily characterized by the red variety, G. elata f. elata. A severe outbreak of tuber brown rot disease was documented in QTM during the harvesting season in Hunan. The fungal pathogen associated with the disease was isolated on potato saccharose agar (PSA) and identified through morphological and phylogenetic analyses. Pathogenicity tests were performed on healthy tubers of G. elata f. elata. The results showed that the representative isolate, named TMB, produced white hyphal colonies with a ring structure, broom-like phialides, partially curved ellipsoidal conidia, and orange–yellow spherical ascocarps on PSA. Phylogenetic analysis of the ITS, LSU, rpb2 and tub2 sequences using Bayesian and maximum-likelihood methods identified the isolate TMB as Clonostachys rosea, based on morphological and phylogenetic data. Pathogenicity tests revealed typical disease symptoms on healthy G. elata tubers 15 days post-inoculation with the isolate TMB. C. rosea is known to cause diseases in economically important crops, but there are no reports of its occurrence on G. elata f. elata in China. This study provides valuable insights into the occurrence, prevention, and control of brown rot disease in G. elata f. elata. [ABSTRACT FROM AUTHOR] |
