Studies On Taxonomy And Flora Of Powdery Mildews (Erysiphales) In Qinling Mts.

Powdery mildew (Erysiphales) is widely distributed around the world. It is an important class of plant pathogenic fungi that can damage many plants including a variety of angiosperms on crops, vegetables, fruit trees, flowers and grass. Powdery mildew mainly destroy plant leaves, stems, petioles, buds and petals, the demaged plants appeared chlorotic, brown, wrinkled. The young leaves often twisted, the plant grow poorly and development abnormaly, even leading to no bear fruit. Epidemic of powdery mildew often result in enormous loss of plant yield and quality, therefore the research on flora of powdery mildew is very important.The Qinling mountains are located in the interlacing area of the floristic regions of north, central and southwest China, forming the natural dividing line between the warm temperate zone and the north subtropical zone. Hence, a great diversity of plants and fungi are apt to be found under this unique geographical condition. The study on flora of powdery mildew (Erysiphales) in the Qinling Mts. is not only provide basic information and data on species diversity of the forest regions, but also provide a theoretical basis for further biological research and control of powdery mildew.Based on the new classification system of Erysiphales, a total of 5 tribes, 8 genera, 53 species of telemorph, and 1 genus, 3 subgenera, 11 species of anomorph powdery mildew, which involving 32 families, 74 genera, 116 species forest plant, in which, 12 species were new record of powdery mildew hosts in China, were identified, described and classified with classification methods of the traditional morphology, the asexual ontogenesis and the ultrastructure of conidia, and a new powdery mildew species Erisiphe duchesnea parasitizing on Duchesnea indica is described, illustrated and distinguished from the morphologically similar species of Erysiphe s.str. on Rosaceae.The preliminary flora analysis of powdery mildew identified showed that Erysiphe emend. accounted for 70% of the total number of powdery mildew of the Qinling forest plants, is the dominant species, followed by Golovinomyces, accounting for 11.7%, Podosphaera is 6.7%, Phyllactinia is 5.0%, and each of Blumeria, Samadaea and Leveillula is 1.7%. On the host plants of the powdery mildew, Asteraceae accounting for 12%, is the main host group of powdery mildew of Qinling, followed by Leguminosae, accounting for 9%, and each of Ranunculaceae, Salicaceae and Lamiaceae is 7%.