Abstract: The causal pathogen of powdery mildew on Urtica triangularis in Urumchi city of China was identified by microscopic observation and molecular method.Conidiophores were cylindrical and produced one conidium at the end of the conidiophore.Conidia were ellipsoid to barrel-shaped,measured 18.75 to 23.75×31.25 to 43.75 μm.Dark brown chasmothecia were found partly embedded in the mycelial felt on leaves,were plat spherical,gregarious to scattered,and 87.5 to 143.75 μm in diameter.Each chasmothecium contained six or eight asci.Asci were sessile,25 to 43.75×37.5 to 68.75 μm,and contained four or five ascospores,each 18.75 to 21.88×25 to 31.25 μm.To further confirm identity of the causal fungus,the internal transcribed spacer (ITS) of fungal rDNA was amplified with universal primers ITS1 and ITS2,and sequenced.The ITS sequence shows 99% similarity with that of Erysiphe urticae on U.dioica from Iranian (Accession No.AB104524).The results showed that powdery mildew fungus on U.triangularis in Urumchi belonged to E.urticae,and had the closest genetic relationship with powdery mildew fungus on U.fissa from Iranian.

Key words: Urtica triangularis, Erysiphe urticae, Identification, Phylogenic analysis

CLC Number: 

• S435.63