Kongtragoul, Pornprapa

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Preferred name
Kongtragoul, Pornprapa
Alternative Name
Kongtragoul, P.
Main Affiliation
Email
pornprapa.ko@kmitl.ac.th

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    Item type:Publication,
    Sensitivity of Phytophthora palmivora Causing Durian Diseases to Metalaxyl-M and Dimethomorph in Southern and Eastern Thailand
    (2025-05-14)
    Kongtragoul, Pornprapa
    ;
    Charoensiri, Sasidara
    ;
    Rimchon, Somkiat
    ;
    Knight, Susan
    Metalaxyl-M (Met-M) and dimethomorph (Dim) are two systemic fungicides commonly used in Thailand to treat durian rot diseases caused by Phytophthora palmivora, a pathogen that significantly affects durian production. Fungicides have long been used by Thai durian farmers to control this infection, but managing the disease has become increasingly challenging in recent years. Monitoring fungicide resistance evolution is essential for effective disease management. In 2020 and 2022, eighty-one and sixty isolates, respectively, were collected from naturally infected durians in southern and eastern Thailand. All isolates were identified as P. palmivora through sporangium formation. Furthermore, 23 out of the 141 isolates were confirmed as P. palmivora based on sequencing of the internal transcribed spacer (ITS) and 5.8S regions of rDNA. All isolates were tested for mycelium growth sensitivity to Met-M and Dim. EC50 values were used to classify sensitivity into three categories: sensitive (S) at EC50 < 1 mgL<sup>-1</sup>, moderately resistant (MR) at EC50 between 1 and 100 mgL<sup>-1</sup>, and resistant (R) at EC50 > 100 mgL<sup>-1</sup>. In southern Thailand, 58% of the isolates were Met-M<sup>R</sup>Dim<sup>S</sup>, and 41.25% were Met-M<sup>S</sup>Dim<sup>S</sup>. In eastern Thailand, 36.67% were Met-M<sup>MR</sup>Dim<sup>S</sup>, and 41.67% were Met-M<sup>S</sup>Dim<sup>S</sup>. These findings indicate that the populations of P. palmivora in the durian orchards in southern and eastern Thailand consisted of a mixture of sensitive, moderately resistant, and resistant strains.
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    Item type:Publication,
    Synergistic effect of salicylhydroxamic acid in quinone outside inhibitor fungicides and its sensitivity on fruit rot pathogens
    (2024-01-01)
    Keeratirawee, K.
    ;
    Kongtragoul, P.
    The synergistic effect of treatment with both salicylhydroxamic acid (SHAM) and treatment with azoxystrobin (AZ), trifloxystrobin (TF), and pyraclostrobin (PR) which are present in Ool (quinone outside inhibitor) on fruit rot pathogens was investigated. Twenty-five fungal pathogen isolates were collected from chili, mango, and durian fruit rot. Ten isolates of Phytophthora palmivora were obtained from durian fruits and 15 Colletotrichum spp. were obtained from chili and mango fruits. The efficiency of SHAM interaction with AZ, TF, and PR at various concentrations to mycelial growth was statistically defined by a synergy factor (SF). A value of a SF above 1 represented the synergism of SHAM and fungicide in QoI to inhibit fungi respiration. The fungicide sensitivity was evaluated with the classification of the levels of sensitivity based on 50% effective concentrations (EC<inf>50</inf>). All tested isolates were susceptible to QoI fungicides at EC<inf>50</inf> lower than 10 mg L<sup>-1</sup>. Only one isolate of Colletotrichum sp. from chili (CC_P003) was intermediately resistant to AZ at 16.52 mg L<sup>-1</sup> EC<inf>50</inf>.