Bursaphelenchus xylophilus is a destructive phytophagous nematode that mainly infects pine species and causes pine wilt disease (PWD). PWD is one of the most devastating diseases that has damaged the pine forests of eastern Asia and Portugal for the last four decades. B. xylophilus infects healthy pine trees through Monochamus beetles and its subsequent proliferation results in destruction of the infected pine trees. The poor water solubility and high cost of currently used trunk-injected chemicals such as avermectin and abamectin for the prevention of PWD are major concerns. Thus, for the identification of new compounds targeting the different targets, five proteins including cathepsin L-like cystein proteinase, peroxiredoxins, hsp90, venome allergen protein and tubulin that are known to be important for development and pathogenicity of B. xylophilus were selected. The compounds were virtually screened against five proposed targets through molecular docking into hypothetical binding sites located in a homology-built protein model. Of the fifteen nematicides screened, amocarzine, mebendazole and flubendazole were judged to bind best. For these best docked compounds, structural and electronic properties were calculated through density functional theory studies. The results emphasize that these compounds could be potential lead compounds that can be further developed into nematicidal chemical against B. xylophilus. However, further studies are required to ascertain the nematicidal activity of these compounds against phytophagous nematode.

Severe attack by a leaf spot disease was found on seedlings of Quercus acutissima in Jeungpyeong, Korea in 2017. Based on the morphological characteristics of the fungus, it was identified as a member of Tubakia. Sequence comparisons based on the ITS and 28S rDNA regions confirmed the identity of the fungus as Tubakia dryina. This is the first report of Tubakia leaf spot caused by T. dryina on Q. acutissima.

In May 2024, a disease resembling felt disease was observed on the stems and branches of Phyllostachys reticulata, with brown coloration appearing on the infected areas, and samples were collected in Byeongbawi Rock and its surroundings, Gochang-gun, Jeonbuk-do. Phylogenetic analysis was performed based on internal transcribed spacer rDNA sequences obtained from the basidiomata. This fungus was classified as Septobasidium sp., showing 97.84% similarity to the Septobasidium sp. strain isolated from the Schisandra chinensis tree. The structural characteristics of the layers of mycelia mat were compared through detailed microscopic examination. Interestingly, while the mats layer structure for commonly known blight diseases are typically single-layered, the basidiomata observed on P. reticulata exhibited a 1 to 3 layered structure. This study represents the first record of felt disease on P. reticulata in Korea, providing a comprehensive report on its morphological and molecular characteristics.

Tree diseases associated with phytoplasma infections predominantly affecting nine host trees have serious impacts on tree growth and cause significant economic losses in South Korea. Loop-mediated isothermal amplification (LAMP)-based primers for early detection were developed to evaluate their accuracy. First, the 16S rRNA gene of phytoplasma was successfully amplified from the extracted DNA of various infected tree species using the polymerase chain reaction method. Two types diagnostic kits developed for phytoplasma detection were evaluated. The first kit detected phytoplasma infection within 30 min under isothermal conditions at 65°C, while the second kit did so within 40 min. Both kits could detect the nine different species of host trees infected with phytoplasma. When tested with 10 ng of the synthetic target gene, the FAM value became detectable at 10 min and remained consistent until 40 min. The lowest detection concentration was 0.01 pg/µL, and the limit of detection was 100 copies/µL. All of the phytoplasmas from nine diseased hosts were early detected. Furthermore, phytoplasma was not detected in healthy specimens, confirming the diagnostic kits' accuracy in distinguishing between healthy and infected strains. The LAMP method confirmed rapid, accurate, and visually assessable detection of phytoplasma, suggesting it will enable early diagnosis of phytoplasma infections in South Korea.

Lonicera vidalii Franch. & Sav. that belongs to the family Caprifoliaceae is a native tree present in Korea and Japan. It is a rare deciduous tree of forest community, mainly occurring in the southern part of Korea. In September 2017, leaf spots on trees, typical symptoms caused by cercosporoid fungi, were observed in Hongneung Arboretum, Seoul, Korea (37°35'37"N 127°02'38"E). Initial symptoms presented as orbicular to irregular and pale brown to dark brown leaf spots of typically 0.2 to 0.9 cm in diameter and, in some cases, merged to form larger blotches across the surface of mature leaves of L. vidalii trees. At infection sites, septate, branched, hyaline to pale brown, smooth and 2–2.5 μm wide hyphae of the fungus were seen emerging through the stomata at the adaxial leaf side. Stromata were large and well-developed, globular, olivaceous brown, 30–50 µm in diameter, and emerging through stomatal openings. Conidiophores were aggregated in loose to dense fascicles through stomatal openings subcylindrica...

Elaeocarpus sylvestris (Lour.) Poir. var. ellipticus (Thunb.) H.Hara, an evergreen tree species native to Jeju Island, South Korea, has experienced a progressive decline associated with phytoplasma infection. This study aimed to evaluate the efficacy of oxytetracycline-based tree injection for suppressing phytoplasma and improving tree vitality. Two formulations—oxytetracycline hydrochloride (4.3%) and oxytetracycline calcium alkyltrimethyl ammonium (17%)—were administered to 40 infected individuals across two sites using a gravity-fed injection system. Treatment efficacy was evaluated based on chlorophyll content as an indicator of physiological recovery, while phytoplasma presence was assessed by PCR at 150 days after injection. The oxytetracycline hydrochloride group showed the highest suppression, with a 70% phytoplasma non-detection rate as determined by PCR analysis. Treated trees exhibited significantly higher chlorophyll content compared to untreated infected controls. These findings suggest that minimally invasive tree injection using oxytetracycline can provide temporary suppression of phytoplasma and support physiological recovery in E. sylvestris.