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POSTERS: Chemical and Biopesticide Control I

P-113 - Occurrence of Resistance in Pyricularia oryzae to QoI Fungicides and the Resistance Mechanism in Korea

Monday, August 4, 2025
3:45 PM - 4:30 PM HST
Location: Exhibit Hall 3

    Presenting Author(s)

  • SK

    Shinhwa Kim

    Student
    Crop Environment Research Division, National Institute of Crop and Food Science, Rural Development Administration
    Cheongju, Cholla-bukto, Republic of Korea

    • Author(s)

  • SS

    Su Jwa Seo

    Rural Development Administration
    wanju-gun, Cholla-bukto, Republic of Korea

  • SK

    Sang-Min Kim

    Rural Development Administration
    wanju-gun, Cholla-bukto, Republic of Korea

  • HC

    Hyunjung Chung

    Rural Development Administration
    wanju-gun, Cholla-bukto, Republic of Korea

  • JC

    Jaebuhm Chun

    Rural Development Administration
    wanju-gun, Cholla-bukto, Republic of Korea

  • NC

    Nak Jung Choi

    Rural Development Administration
    wanju-gun, Cholla-bukto, Republic of Korea

  • JL

    Jang Ho Lee

    Rural Development Administration
    wanju-gun, Cholla-bukto, Republic of Korea

  • HK

    Heung Tae Kim

    Chungbuk National University
    Cheongju, Ch'ungch'ong-bukto, Republic of Korea

Abstract Text:

Rice blast is a significant disease in Korea, driven by extensive rice cultivation, causing substantial yield losses. Chemical fungicides, particularly Quinone outside Inhibitors (QoI), have been the predominant control method, with increasing use of unmanned aerial vehicles (UAVs) for aerial applications. A recent review of 41 registered aerial fungicides for rice blast control revealed 19 are from the QoI group. Reports suggest large-scale outbreaks under conducive conditions, with fungicide resistance emerging as a key factor. This study aims to assess QoI fungicide resistance in the rice blast pathogen Pyricularia oryzae to guide sustainable management strategies. A total of 655 isolates, collected from 1984 to 2023, were evaluated using the agar dilution method with pyraclostrobin (11% SC). Results showed sensitivity to the fungicide from 1984 to 2018. However, two isolates from Jeonju-Si, Jeonbuk State, exhibited resistance in 2019. The prevalence of resistance rose steadily in subsequent years, with 13 isolates in 2020, 14 in 2021, 55 in 2022, and 91 in 2023. Genetic analysis of the cytochrome b (cyt b) gene in resistant isolates identified a G143A point mutation. A molecular marker was developed to detect these resistant isolates. These findings highlight the need for continuous fungicide resistance monitoring, especially in outbreak-prone regions, and underscore the importance of incorporating these insights into more effective and sustainable management strategies.