Biological characterization and in vitro fungicide screening of a new pathogen of basal stem rot of Schisandra chinensis in Jilin Province, China

Taiping Tian¹Mengqi wang²Jingmeng zhu¹Yining Sun¹Mingjie Ma¹Guoliang Liu¹Jinshuo Wang¹Bing Zhao¹Yiping Yan¹Yue Wang¹Yanli Wang¹Changyu Li¹Dongyin Wang¹Fang Yang¹Peilei Xu^1*Wenpeng Lu^1*

• ¹Institute of Specialty Products, Chinese Academy of Agricultural Sciences, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
• ²Institute of Special Animal and Plant Sciences, CAAS, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China

Schisandra chinensis (Turcz.) Baill., a widely cultivated medicinal plant of significant economic value, constitutes an important pillar of specialty agriculture in Jilin Province. In 2024, a novel basal stem rot disease was first observed in the main production area of Latai Village, Liudaogou Town, Linjiang City, Jilin Province, characterized by stem-base necrosis, vascular-bundle browning, plant wilting and death, often accompanied by soft rot under high humidity.Morphological examination and PCR amplification and sequencing of the internal transcribed spacer (ITS), β-tubulin (TUB) and translation elongation factor 1-α (TEF1-α) genes identified the pathogen as Ilyonectria robusta; Koch's postulates (including re-isolation and re-identification) confirmed its high pathogenicity to detached stems, seedlings, in-planta plants and tissue-cultured plantlets. To our knowledge, this is the first global report of I. robusta causing basal stem rot on S. chinensis. To elucidate its biology and inform future disease management, we assessed the effects of culture medium, temperature, light regime, pH, carbon and nitrogen sources on mycelial growth. The optimal media were CDA and CMA; the optimal temperature was 25 °C; continuous darkness and pH 7 favored growth; sodium nitrate and lactose were the most effective nitrogen and carbon sources, respectively. In vitro screening of seven fungicides (three chemical and four plant-derived) revealed that 98% fluazinam exhibited the highest inhibition rate against I. robusta, with an EC₅₀ of 5.658 mg/L. This study not only provides new insights into the etiology of basal stem rot in Jilin Province but also reveals key biological characteristics of the pathogen and identifies a promising candidate fungicide for integrated disease control.