A powdery mildew parasitizing Koelreuteria spp. was first described under the name Uncinula koelreuteriae Miyake and later transferred to the genus Typhulochaeta. Based on morphological and molecular data of several herbarium specimens collected from Korea, the generic placement of Typhulochaeta is discussed and T. koelreuteriae is combined in the genus Sawadaea. Redescription and epitypification of this species is provided hereby.