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This study was conducted to identify a cheap and suitable culture medium for the mycelial growth and sporulation of Stemphylium vesicarium and to determine the cultural and morphological variability of this pathogen. A total of 24 isolates of S. vesicarium collected from eight different onion growing areas were characterized in terms of cultural and morphological aspects. Front colony colors were greenish brown to dirty white, deep grey to whitish, light grey to whitish, deep greenish white, light grey and dirty white to greenish. Reverse colony colors were brown, deep brown and light brown. Colony shapes were circular and irregular with umbonate, raised and flat type colony elevation. Colony textures were cottony, fluffy and velvety with entire, undulate and filiform type colony margin. Among the culture media, V-7 juice agar found to be the most suitable culture media for mycelial growth of S. vesicarium. The sporulation of the fungus was remarkably influenced by V-7 juice mixed with potato dextrose agar (PDA) media, this media exhibited the highest sporulation (87.76-169.0/mm 2 ) of S. vesicariumin comparison with other media. The minimum days (28 d to 31 d) for conidial production were observed on V-7 juice agar medium. The length of conidia varied from 14.6 µm to 30.6 µm. The maximum mean length of conidia was 29.97 µm found in isolate DSSA, while the minimum mean length 17.36 µm was found in isolate MSMM 02. The breadth of conidia ranged from 4.7 µm to 15.7 µm. The maximum mean breadth of conidia was 12.55 µm found in the isolate DSSA, while the minimum mean breadth 9.760 µm was found in the isolate CCKH 02. The horizontal septation varied from 1 to 3 and the longitudinal septation varied from 0 to 4.

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