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This study focused on the persistence, distribution, and efficacy of trunk-injected pesticides in Pinus koraiensis (Korean pine) with regard to controlling pinewood nematodes (PWNs, Bursaphelenchus xylophilus), the causative agent of pine wilt disease (PWD). In this study, we compared pesticide residues in the needles and branches of Korean pine, revealing significant declines in pesticide residues over time after treatments were applied. Notably, abamectin residues decreased from 0.2325 mg/kg to 0.0901 mg/kg in branches over a period of 18 months. In contrast, emamectin benzoate showed a variation in residue decline depending on the formulation, with the residue level in branches decreasing from 0.1220 mg/kg to 0.0328 mg/kg over the same period. From a spatial perspective, the results revealed minimal differences in pesticide residue at varying tree heights, although a decrease in upper canopy residue was observed in some cases. The nematicidal efficacy test demonstrated that none of the treated trees developed PWN symptoms. Overall, the findings suggest that the trunk-injected pesticides abamectin and emamectin benzoate can persist for two years, with the residue levels being sufficient to prevent PWN propagation, even when the levels are below critical inhibition concentrations. [ABSTRACT FROM AUTHOR]

The pinewood nematode (PWN), Bursaphelenchus xylophilus (Steiner & Bührer), causes pine wilt disease (PWD) resulting in severe environmental damage to pine forest ecosystems worldwide. To develop alternative strategies for managing PWD, the nematicidal activities of two sweeteners, erythritol and saccharin, were investigated. Among these two sweeteners, saccharin induced higher mortality in a dose-dependent manner. The LC50 and LC90 values of saccharin were estimated to be 0.321 M and 0.615 M, respectively. However, erythritol did not exhibit nematicidal activities. The results of our study demonstrated that saccharin is lethal to PWN and shows nematicidal effects in a dose-dependent manner. Although the mechanisms of saccharin toxicity are not yet investigated, saccharin could be used as an effective alternative for the management of PWN.

Simple Summary: The study assessed a pheromone-based mating disruption (MD) for the control of Conogethes punctiferalis in Korean chestnut orchards. Over two years, field trials showed that MD effectively reduced male C. punctiferalis numbers, with male catch inhibition (MCI) ranging from 70.5% to 95.1%. MD treatments, including single-dosage (TS) and double-concentration (TD) or two-application (TT) methods, significantly reduced fruit damage. In 2022, TS achieved 63.9–73.6% efficacy, while in 2023, TD and TT showed variable but notable reductions in pest numbers and fruit damage. The study confirms the MD's efficacy in mitigating C. punctiferalis damage in chestnut orchards, highlighting its potential as an eco-friendly pest management strategy in agroforestry systems. Chestnuts (Castanea crenata Siebold and Zucc.) are one of the major agroforestry products in Korea, and Conogethes punctiferalis is a major pest of the chestnut fruit. Pheromone-based mating disruption (MD) has emerged as a promising eco-friendly approach to reduce population levels and ultimately mitigate fruit damage. Field trials were conducted over two years (2022–2023) in two commercial chestnut orchards in Central Korea that were infested with C. punctiferalis. Compared with the control treatment, the MD treatment effectively reduced the number of male C. punctiferalis captured in the MD treatment plots. Male catch inhibition (MCI) rates ranged from 70.5% to 82.7% in 2022 and from 87.8% to 95.1% in 2023. The MD efficacy (%) was calculated based on the total number of chestnut fruits collected and the number of fruits damaged by C. punctiferalis. In 2022, the MD efficacy of the single-dosage treatment (TS, 50 g/ha) was 63.9% in Orchard A and 73.6% in Orchard B. In 2023, the MD efficacies of the double-dosage treatment (TD, 100 g/ha) and the two-application treatment (TT, 50 g/ha in June and August) were 60.2% and 77.9% in Orchard A and 50.9% and 64.8% in Orchard B, respectively. This study confirms the efficacy of pheromone-based MD in reducing the C. punctiferalis numbers in chestnut orchards and damage to chestnut fruits. [ABSTRACT FROM AUTHOR]