Resistance of Venturia nashicola to thiophanate-methyl and benomyl: build-up and decline of resistance in the field |
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Authors: | HIDEO ISHII HIDEO UDAGAWA HARUO YANASE AKIRA YAMAGUCHI |
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Institution: | Fruit Tree Research Station, Yatabe, Tsukuba, Ibaraki 305, Japan;Tottori Fruit Tree Experiment Station, Daiei, Tohhaku, Tottori 689-22, Japan |
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Abstract: | Changes in the proportion of benzimidazole-resistant strains in populations of Venturia nashicola were monitored in pear orchards. Successive applications of thiophanate-methyl increased the level of resistance in the populations. When the application of benzimidazoles was stopped and other fungicides were applied, the proportion of highly resistant strains gradually decreased and the proportion of intermediately resistant, weakly resistant and sensitive strains increased. It is suggested that this phenomenon is an example of genetic homeostasis within microbial populations. |
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