Characterization of Powdery Mildew Caused by Podosphaera fusca Infecting Melothria japonica(Thunb.) Maxim

Abstract

From August to October of both 2012 and 2013, powdery mildew was observed onwhite-fruited creeping cucumber(Melothria japonica [Thunb.] Maxim.) at Jinju, Korea. Whitemycelial colonies were observed on leaves and petioles. Lesions of severe infections werediscolored or brown. In the present study, the morphological features of the anamorphic andteleomorphic reproductive stages of the fungus were studied. To complete the fungalidentification, the sequence of the internal transcribed spacer region of a ribosomal RNA(ITSrRNA) gene was determined. Based on morphological characteristics and analysis of the ITSrRNA gene, the fungus causing the powdery mildew symptoms was identified as Podosphaerafusca. Although the host range of powdery mildew caused by P. fusca has been previouslydescribed, no full description and illustration of the infection, including symptoms and signs onwhite-fruited creeping cucumber, has yet appeared. To the best of our knowledge, this is thefirst full description of powdery mildew on white-fruited creeping cucumber, featuring molecularidentification, symptoms, and signs.