Аннотация:Life cycle, pathogenicity, conditions for conidial germination and mycelial growth and taxonomic classification of Cercospora pyracanthae Katsuki causing brown spot of Pyracantha spp. were examined. Among Pyracantha species plants, P. angustifolia (Franchet) Schneider was highly susceptible. Conidia of the causal fungus, produced on overwintered and diseased leaves on trees, acted as the source of primary infection of newly sprouted leaves in May and June. Then the overwintered and diseased leaves gradually defoliated. Conidia germinated in vitro within 12 hr. They could germinate from 5 to 35°C with an optimum temperature at 25°C, and from pH 3 to 9 with an optimum between pH 4 and 9. Mycelia grew well on various natural and chemically defined agar media. They grew well at 25°C within the range of 5 to 35°C, and at pH 4 to 9 with the range from 3 to 9. Germination of conidia was strongly suppressed by CuSO4⋅5H2O, maneb and thiophanatemethyl. Sporulation experiments on agar media were successful. After detailed examination under light and scanning electron microscopes, the causal fungus was placed in the genus Pseudocercospora Speg. emend. Deighton (1976) and renamed under a new combination, P. pyracanthae (Katsuki) Nakashima et Kobayashi.
