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POSTERS: Integrated Pest Management II

P-318 - Efficacy of Defense Inducers in Reducing Ambrosia Beetle Attacks and Colonization under Water Stress and Root Rot Pathogen Pressure

Tuesday, August 5, 2025
9:30 AM - 10:15 AM HST
Location: Exhibit Hall 3

    Author(s)

  • MP

    Madhav Parajuli

    USDA-ARS
    McMinnville, Tennessee, United States

  • CO

    Cansu Oksel, n/a

    Post-doctoral
    Tennessee State University
    McMinnville, Tennessee, United States

    • Presenting Author(s)

  • FB

    Fulya Baysal-Gurel, n/a

    Associate Professor
    Tennessee State University, Otis L. Floyd Nursery Research Center, Department of Agriculture Sciences and Engineering
    McMinnville, TN, USA

    • Author(s)

  • CR

    Christopher M. Ranger

    USDA-ARS
    Wooster, Ohio, United States

Abstract Text: Biotic and abiotic stressors increase the susceptibility of nursery plants to ambrosia beetles. This study examined the effects of water stress and root rot pressure on the susceptibility of flowering dogwoods to ambrosia beetle attacks and colonization. Additionally, the efficacy of defense inducers, Actigard and Daconil Action, in reducing beetle attacks and colonization was assessed. Three-year-old container-grown dogwoods were subjected to either flooding or adequate watering, with or without Phytophthora nicotianae inoculation, and were then treated with Actigard or Daconil Action as either a foliar spray or soil drench, while a control group remained untreated. Two trials were conducted during the summer of 2023 in McMinnville, TN. The results indicated that beetle attacks occurred exclusively on flooded plants. Non-inoculated plants had more beetle attacks and greater colonization than inoculated plants in at least one of the two trials.

Actigard, applied as either a foliar spray or a drench, significantly reduced beetle attacks, gallery formation and depth, fungal colonization, and the presence of beetle eggs, larvae, and adults inside galleries compared to untreated plants. However, Daconil Action did not affect beetle attacks or colonization. Higher concentrations of ethanol, an attractant for ambrosia beetles, were detected in the tissues of flooded plants compared to those of non-flooded plants. These findings offer important insights for growers, aiding in developing effective strategies to manage ambrosia beetles under flooding and root rot pathogen pressure.