Morpho-molecular Identification and Chemical control of Alternaria alternata,causing leaf blight of Gardenia jasminoides Eills in China

Abstract Gardenia jasminoides Eills is a traditional aromatic and medicinal plant that is widely cultivated in China. In 2020, a severe leaf disease on Gardenia was observed in a growing herbal medicine area in Jian County, of Jiangxi Province, China. The causal agent was identified as Alternaria alternata (Fr.) Keissler. by amplification and sequencing the internal transcribed spacer (ITS) region, followed by phylogenetic analysis. Koch's postulates were confirmed by a pathogenicity test conducted with healthy gardenia, including reisolation and identification. To our knowledge, this is the first report of leaf blight caused by Alternaria alternata on Gardenia jasminoides Eills in JiangXi, China. PDA plate bacteriostatic experiment results showed that: Hexaconazole had the best inhibiting effect, which the EC 50 was 14.45 ppm. Therefore, the results are preliminary but promising for future field applications.