Identification and Host Range of Powdery Mildew of Begonia. J. A. Quinn, Graduate Research Associate, Department of Plant Pathology, The Ohio State University, Columbus 43210. C. C. Powell, Jr., Associate Professor, the Ohio Agricultural Research and Development Center, Wooster 44691. Plant Dis. 65:68-70. . This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/PD-65-68.

The intrageneric and intergeneric host range of two races of Oidium begoniae was investigated. The races are morphologically identical, but only one race has the ability to infect the Aphrodite cultivars of Begonia × hiemalis (Rieger elatior begonias). In the intergeneric host range study, Sphaerotheca fuliginea from pumpkin (Cucurbita mixta ‘Spooky’) infected begonia cultivar Schwabenland Red but grew slowly and had conidial states different from those of O. begoniae. Begonia species resistant to both races of O. begoniae had lower optimum temperatures for infection and hyphal growth.

Keyword(s): Erysiphe cichoracearum, Erysiphe polyphaga, Microsphaera tarnavschii.