Jerusalem artichoke (JA) has increasingly established feral populations with its introduction worldwide. In mid-June, 2019, white colonies of powdery mildew (PM) appeared on wild JA in Shenyang, Liaoning, China. ITS sequences retrieved from the pathogen clustered within the Golovinomyces lineage, and holomorph characteristics agreed with those of G. latisporus rather than G. ambrosiae. Pathogenicity tests confirmed that this pathogen caused the PM symptoms observed in the field. The PM pathogen was eventually identified as G. latisporus, the sole species in a clade including our combined PMITS (powdery mildew specific ITS), IGS (intergenic spacer), TUB2 (beta-tubulin) and CHS1 (chitin synthase I) sequences. In three JA invaded plant communities, G. latisporus showed high specificity for this introduced host among plants of 21 genera from 15 families. This is a first report of G. latisporus infecting feral JA in Liaoning, Northeast China. Cross-infective risks of G. latisporus between wild and cultivar JA, as well as its related sunflowers, deserve more attention as worldwide feralization of JA is increasing.