Abstract: 【Objective】To isolate and identify the pathogens of sclerotinia rot in milk thistle planting regions in Hulun Buir,Inner Mongolia,and to clarify the control effect of different chemical agents on milk thistle sclerotinia rot.【Methods】The milk thistle sclerotinia rot disease samples were collected for pathogen isolation and purification,then verified by Koch′s Postulation,and identified by morphological and molecular biology. Using water as control,40% Dimethachlon WP,“Pulvtong” plant immune protein,450 g/L Prochloraz EW,50% Carbendazim WP as test agents,the control effect of the four agents on milk thistle sclerotinia rot and their effect on yield of milk thistle were analyzed.【Results】A total of 15 strains were isolated and purified. The NCBI Blast results showed that the isolated strains were >99% similar to Sclerotinia sclerotiorum（Lib.）de Bary. The four test agents all effectively increased the yield of milk thistle,with the control effect in the range of 32.77%-53.78%,and yield increase rate at 16.31%-37.05%.Spraying 2 999 g/hm² of “Pulvtong” plant immune protein had the best control effect on sclerotinia rot（control effect at 53.78%） and good yield increase effect（yield increase rate at 16.88%）. Spraying 450 g/L Prochloraz EW had poor control effect（control effect at 32.77%）,but best yield increase effect（yield increase rate at 37.05%）.【Conclusion】The four test agents were all safe to milk thistle.Spraying 2 999 g/hm² of “Pulvtong” plant immune protein had highest control effect and good yield increase rate,could be used as the preferred agent for the prevention and control of sclerotinia rot in milk thistle planting regions in Hulun Buir,Inner Mongolia.

Key words: Milk thistle, Sclerotinia rot, Pathogen identification, Sclerotinia sclerotiorum（Lib.） de Bary, Koch′s Postulation, Control effect