Morphology

Cultures of C. platani are at first hyaline and more or less dense, depending on the culture medium, becoming brownish-green and giving off a pronounced banana smell, the intensity of which varies with culture medium. Growth is rapid (5 mm in 24 h at 24°C on potato dextrose agar). Perithecia (diam: 200 µm) have long necks (400-800 µm), although not all isolates produce these structures, while in others, aborted perithecia, never attaining maturity, are formed. Ascospores (diam: 4-8 µm) have distinctive bowler hat shapes.

In culture, three types of conidia form: (1) hyaline truncated cylindrical endoconidia (5-40 x 3-6 µm) in long rigid arched chains on 60-90 µm long conidiophores, produced on an approximately daily cycle; (2) more rarely, doliform endoconidia form, very pale in colour, dimensions of 7-12 x 6-9 µm, in short chains; (3) thick-walled endoconidia (chlamydospores) are bulbous, brownish-green, 11-19 x 9-15 µm. Conidia are very numerous in infected wood (and thus in sawdust). For more information, see Hunt (1956), Webster & Butler (1967), Ferrari & Pichenot (1974).