Frequency of Alternaria brassicicola in commercial cabbage seeds in Japan |
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Authors: | Masaharu Kubota Kazuo Abiko Yukio Yanagisawa Kazufumi Nishi |
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Institution: | (1) National Institute of Vegetable and Tea Science, 360 Kusawa Ano, Tsu 514-2392, Japan;(2) JA Zennou Shiga, Shiga, Japan;(3) Gunma Seibu Agricultural Office, Takasaki, Japan |
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Abstract: | Plug seedlings, widely used in cabbage cultivation in Japan, are often infected by seed-borne pathogens, especially the serious
pathogen Alternaria brassicicola. Because information on seed infestation is scant in Japan, we investigated fungal infestation in commercial batches of cabbage
seeds produced between 1984 and 2001. A total of 123 lots were divided into six groups by production period (1984–1989, 1994–1998,
and 2001) and by use or nonuse of fungicide. One hundred seeds from each lot were incubated separately on agar at 25°C to
isolate the predominant fungus. Alternaria brassicicola was isolated most frequently, 0%–94% of the seeds depending on seed lot or 6%–21% of the seeds grouped by production period
and fungicide treatment. Thus, the pathogen was isolated even from seeds refrigerated for 17 years. Alternaria brassicicola accounted for 57%–95% of all isolated fungi by the group and was higher on older or fungicide-treated seeds. Seeds that were
not treated with fungicide in lots grouped by production districts in western Japan were infested with A. brassicicola at a rate of over 12%, higher than that in the eastern region (<4%). Infestation was higher in the warmer areas of Japan.
Eighty-five isolates, other than A. brassicicola, produced spots on cabbage cotyledons, although they were not isolated as frequently: less than 5% of seeds by group separated
by production period and fungicide treatment. Most of these isolates were Alternaria alternata. This is the first report on the frequency of fungal infestation of commercial cabbage seeds in Japan. |
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Keywords: | Cabbage seed Fungal isolation Japan Alternaria brassicicola |
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