Isolation and Identification of Pathogens of Algal Spots of Torreya grandis cv. 'Merrillii' and Screening of the Algicides

[Objective]The study aims to explore the pathogens of algal spots of Torreya grandis cv. 'Merrillii' and their biological characteristics, as well as screen efficient algicides, so as to provide scientific basis for controlling the disease.[Method]The diseased leaves of T. grandis cv. 'Merrillii' were collected from the main planting areas in Zhejiang Province, and the algae were isolated from diseased leaves, and then identified by traditional morphological observation combined with molecular biological methods. The biological characteristics of the pathogenic algae were studied, and efficient algicides for controlling the disease were screened by laboratory virulence assay and the field control experiment.[Result]1) Three groups of synantectic pathogenic algae were isolated from algal spots, and they were identified as Desmodesmus armatus, Klebsormidium flaccidum and Tritostichococcus corticulus, respectively, based on the morphological characteristics and the SSU-ITS sequence analysis, all of which were ne