インゲンの連作障害とPythium spp.の関係

概要

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The bean plants in monoculture plots in Hokkaido Prefectural Kitami Agricultural Experiment Station showed severe necrosis of roots and retarded the growth in the middle of July in 1979, while those in 6-year rotation plots seemed healthy. The height and yields of bean plants in monoculture were about 80 % and 70 % of those in rotation. These appearences are said to be caused by the long-term monoculture. Pythium myriotylum and an unidentified Pythium sp., highly pathogenic to bean plants, were isolated only from the necrotic root tissues in monoculture. P. spinosum, P. paroecandrum and P. ultimum, mildly or scarcely pathogenic to bean plants, were recovered from the roots in moculture and also those in rotation. Populations of P. myriotylum and Pythium sp. in rhizosphere and nonrhizosphere soils of bean plants in monoculture were remarkably high. There was no difference in the populations of the other Pythium spp. in the soils of monoculture and rotation. When ridomil, N-(2, 6-dimethylphenyl)-N-(methoxyacetyl) alanine methyl ester, which is one of the selective fungicides against Oomycetes, was drenched to the soil collected from the monoculture plots, the roots of bean seedlings grown in the soil remained healthy as those in the untreated rotation soil. These results suggest that the symptoms of bean plants in monocuture are caused by the infections of P. myriotylum and an unidentified Pythium sp.
日本植物病理学会の論文
1981-07-25