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Remarks (public):For a complete description including images see 
Remarks (internal):Although it has been stated that Phleum pratense is the only host, Jacques (1941) suggested that similar species of Cladosporium isolated from other members of the Gramineae may prove to be conspecific. Sundheim & Aavold (1969) carried out innoculation tests and found that C. phlei did not cause symptoms of eyespot on any other members of the Gramineae tested. Cladosporium phlei is known to produce a non host-specific toxin, phleichrome (Yoshihara et al., 1975), which was shown to produce phytotoxic lesions on the leaves of P. pratense similar to those produced by the fungus (56, 1448; 63, 701). Phleichrome has been the subject of much biochemical research (53, 3529, 56, 1448, 4310; 59, 4661; 60, 1489; 61, 5808). Infections of C. phlei are heaviest during the late summer and may cause up to 30% reduction of yield.
Description type:Non-original description 
Description:Cladosporium phlei (C.T. Greg.) G.A. de Vries, Contribution to the knowledge of the genus Cladosporium Link ex Fr., p. 49, Baarn, 1952.
Heterosporium phlei C.T. Greg., 1919.
Leaf lesions grey or fawn obovate spots with purple borders, (0·5-) 2-3 mm diam. Mycelium abundant, superficial or immersed, composed of colourless to olive-brown, thin to thick-walled, cylindrical or ± irregular, much branched, septate hyphae, 2-12 µm wide. Stroma pigmented, dark, superficial, rarely exceeding 75 µm wide, composed of thick-walled, ± isodiametric cells, (5-) 5,5-8 (-10) µm diam. Conidiophores arising singly, in pairs or fascicles from the mycelium or stroma, straight or flexuous, unbranched, septate, mid- to pale-olivaceous brown, smooth, up to 300 x 6-9 µm, swollen at the apex only or with intercalary nodes. Conidiogenous cells swollen and terminal, becoming intercalary by elongation of the conidiophore apex. Conidia ovate, oblong or obovate, usually somewhat broader at the distal end, with or without a constriction in the middle, 1-3 (-5)-septate, usually 1-septate, echinulate, pale to dark brown, 13-36 (-57) x 6-14 µm, averaging 23 x 9 µm. Conidial development initiation holoblastic from sympodially proliferating conidiogenous cells; conidia usually solitary, occasionally in short unbranched acropetal chains; secession schizolytic, leaving a thickened, pigmented and not or slightly protuberant scar.
Hosts: Phleum pratense (cf. notes).
Disease: Eyespot of timothy.
Geographical distribution: Asia: Japan. Australasia: New Zealand. Europe: Denmark, Eire, England, Northern Ireland, Norway, Sweden, USSR (Byelorussia), West Germany. North America: Canada (Quebec), USA (New York, Oregon, Washington).
Physiological specialization: None reported.
Transmission: By airborne dispersal of conidia, and by conidia on seeds of the host. Infection requires a high humidity (80-100%) to be successful. Spores germinate at between 3 and 33°C, optimally at 24°C (55, 5249).
Literature: Jacques, Contributions de l'Institut Botanique de l'Université de Montréal 39: 1-46, 1941; Sunheim & Aarvold, Meldinger fra Norges LandbrakshagskÀ¸le 48 (26): 1-10, 1969; Yoshihara et al., Agricultural and Biological Chemistry 39: 1683-1684, 1975.
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