大阪府におけるSDHI耐性ナスすすかび病菌の発生

抄録

In this study, we evaluated the efficacy of penthiopyrad, isopyrazam and pyraziflumid against Mycovellosiella nattrassii isolates. These isolates, collected from eggplants in Osaka Prefecture, Japan, in 2024, had previously shown reduced sensitivity to succinate dehydrogenase inhibitors (SDHI) in culture medium tests (Yasumatsuya et al., 2025). Three strains (N8, N9 and N10) were tested. N8 and N10 demonstrated low sensitivity to penthiopyrad, isopyrazam and pyraziflumid on culture medium, were resistant to these SDHI on plant body. N9, which was sensitive to pyraziflumid and resistant to penthiopyrad, isopyrazam on culture medium, was sensitive to pyraziflumid and resistant to penthiopyrad, isopyrazam on plant body.

The results of sensitivity to pyraziflumid on culture medium were consistent with the results on plant body. These results indicate the development of SDHI fungicide resistance in Mycovellosiella nattrassii (the causal agent of eggplant leaf mold) in Osaka Prefecture, and suggest the potential for the culture medium test to distinguish between sensitivity and resistance to pyraziflumid.