Chili pepper (Capsicum annuum L.) is a major vegetable crop in Korea. In August 2018 and July 2025, wilting was observed in chili pepper fields in Jeongeup (35.56°N, 126.86°E) and Suncheon (35.00°N, 127.51°E), Republic of Korea. The areas of the observed fields were 0.2 ha and 0.3 ha, respectively, and disease incidence ranged from approximately 5% and reached up to 30% in affected fields. To identify the causal agent, symptomatic plants were randomly selected from each field. Basal stem tissues from the symptomatic plants were surface-disinfested in 1% sodium hypochlorite for 1 min, rinsed three times with sterile distilled water, and a total of 21 segments (seven per plant) were plated onto water agar (WA). Plates were incubated at 25°C for 5 days, and single-hyphal-tip cultures were obtained. Fungal isolates were obtained from all 21 segments, and three representative isolates (NC18-688, NC18-689, and P017) were selected for further characterization. For cultural characterization, 5-mm-diam. mycelial plugs were placed on potato dextrose agar (PDA) and incubated at 25°C for 3 days. Colonies were dark brown to dark olive and darkened with age, reaching 77 ± 7 mm in diameter. Although the overall colony morphology was consistent with M. phaseolina, variations among the three isolates were observed. Isolates NC18-688 and P017 exhibited rapid and abundant microsclerotia formation with minimal mycelial growth. In contrast, isolate NC18-689 produced relatively abundant mycelium but showed the slowest rate of microsclerotia formation. For morphological characterization, 5-mm-diam. plugs were transferred to oatmeal agar (OMA) and incubated at 28°C in the dark for 24 h, followed by incubation under UV light at 28°C for 5 days (Zhao et al. 2020). Microsclerotia were black, smooth, round to oblong, and 38.6–79.6 µm in diameter (n = 50). Pycnidia formed on OMA but not on PDA or WA; they were black, thin-walled, globose, with 0–1 ostiole, and 139.7–234.2 µm in diameter. Conidiogenous cells and conidia were observed from ruptured pycnidia. Conidiogenous cells were hyaline, thin-walled, cylindrical to lageniform, producing conidia at the apex. Conidia were hyaline, smooth-walled, aseptate, granular, ellipsoid to obovoid, and 16.5–22.1 × 6.1–9.7 µm. These characteristics were consistent with descriptions of Macrophomina phaseolina (Huda-Shakirah et al. 2019). Molecular identification was performed by PCR amplification and sequencing of the ITS, EF1-α, and β-tubulin (TUB) regions using primers ITS1/ITS4 (White et al. 1990), EF-728F/EF-986R (Carbone and Kohn 1999), and Bt2a/Bt2b (Glass and Donaldson 1995), respectively. Sequences were deposited in GenBank (accession nos. PX775556–PX775558 [ITS], PX833991–PX833993 [EF1-α], and PX833994–PX833996 [TUB]). Concatenated ITS, EF1-α, and TUB sequences were used for phylogenetic analysis. Bayesian inference (BI) analysis was performed using MrBayes v3.2.7. The GTR+I+G (General Time Reversible with proportion of invariable sites and gamma-distributed rate variation) model was selected as the best-fit nucleotide substitution model, with parameters set to Nst = 6 and Rates = Invgamma. The Metropolis-coupled Markov chain Monte Carlo (MCMCMC) algorithm was run with four chains for 100,000 generations, and trees were sampled every 1,000 generations. The first 25% of the sampled trees was discarded as burn-in, and the remaining trees were used to construct a consensus tree. Although the three isolates shared 100% sequence identity in both the ITS (377 bp) and TUB (405 bp) regions, minor nucleotide variations were detected in the EF1-α region (9 polymorphic sites out of 245 bp; 96.33% identity). Overall, the isolates displayed a high sequence similarity of 99.12% across the concatenated regions (1,018/1,027 bp), reflecting subtle intraspecific genetic diversity. Bayesian inference placed the three isolates in a clade with M. phaseolina reference isolates CBS 162.25, CBS 205.47, and CBS 227.33. Pathogenicity was tested by soil infestation using sterilized sorghum grain inoculum. Sterilized grains were inoculated with ten 5-mm-diam. PDA plugs from actively growing cultures; control grains received ten sterile PDA plugs. After incubation at 25°C in the dark for 14 days, colonized sorghum was mixed with potting soil at 5% (v/v). Three-week-old chili pepper seedlings were transplanted into infested soil (five replicate experiments). Wilting developed approximately 2 weeks after transplanting in inoculated plants but not in controls. Among the three isolates, NC18-688 showed the highest virulence in pathogenicity assays. The pathogen was re-isolated from symptomatic tissues and identified as M. phaseolina, fulfilling Koch’s postulates. However, the pathogen was not recovered from any control plants. To our knowledge, this is the first report of charcoal rot of chili pepper caused by M. phaseolina in Korea. Given that warm and dry conditions favor charcoal rot, continued monitoring is needed as climate change may increase disease risk in chili pepper–growing regions of Korea.

Kimchi Cabbage (Brassica rapa L. subsp. pekinensis [Lour.] Hanelt) belonging to the Brassicaceae family is a globally cultivated vegetable, valued for its nutritional content and versatility in cooking applications (Hwang et al. 2023). In Korea, it holds particular significance as the primary ingredient in Kimchi, a traditional fermented food integral to Korean dish and culture. In July 2023, symptoms of wilting and yellowing leaves were observed in Taebaek, the Republic of Korea (37°9'50.6"N, 128°59'8.03"E). The average incidence was approximately 1%. The diseased plants with browning inside the root were cut and surface-sterilized with 1% sodium hypochlorite (NaOCl) for 1 min followed by rinsing twice in sterile distilled water. The tissue pieces were placed on 1% water agar (WA) and incubated at 25℃ for 5 days. Through single spore isolation method, five isolates (SKH23014, SKH23015, SKH23024, SKH23025, and SKH23026) were collected. For cultural and morphological characteristics, 5 mm disk with mycelium were cultured on potato dextrose agar (PDA), malt extract agar (MEA), and oatmeal agar (OA) at 25℃ for 10 days. The mycelial growth (diameter) were 44-55 mm on PDA, 50.5-60.5 mm on MEA, 51-56.7 mm on OA. Colonies on OA were buff to pale brown, slimy, and aerial mycelium were white and rarely present. Conidia were hyaline, smooth, thin-walled, elliptical to ovoid, 0-1 septate, and 4.7-10.8 × 2.3-4 μm in size (n>50). Chlamydospores were absent. These cultural and morphological characteristics were similar to those of previously reported Plectosphaerella cucumerina (Carlucci et al. 2012; Mirtalebi and Banihashemi 2017). For molecular analysis, three gene regions, including the internal transcribed spacer (ITS), translation elongation facter 1 alpha (EF1-α), and large subunit rRNA (LSU) gene were amplified and sequenced using ITS1F/ITS4 (Gardes and Bruns 1993; White et al. 1990), EF1-983F/EF-2218R (Rehner and Buckley 2005), LR0R/LR7 (Vilgalys and Hester 1990), respectively. The obtained sequences were deposited in NCBI GenBank (GenBank accession no. PV589464-PV589468 for ITS, PV593115-PV593119 for EF1-α, and PV589472-PV589476 for LSU). BLASTn homology searches for these nucleotides showed 98 to 100% identity to the ITS sequences (MH855387, 501/509 bp), the EF-1α sequences (LR026492, 785/787 bp), and the LSU sequences (MH855387, 831/833 bp) of P. cucumerina strain CBS 137.33. Through cultural/morphological characteristics and molecular analysis using the maximum likelihood method, they were identified as P. cucumerina. Pathogenicity assays were conducted using the soil inoculation method with cornmeal sand inoculum. For each treatment, cornmeal sand was inoculated using 15 PDA disks (Ø 5mm) that had been colonized by a single isolate. Control treatments used 15 uninoculated PDA disks (Ø 5mm). Cornmeal sand inoculum was incubated in the dark at 25℃ for two weeks. About three-week-old plants were transplanted into infested soil (3 plants/isolate), which was prepared by mixing the inoculum with soil at a ratio of 3:7 (v/v). These experiments were repeated three times. Approximately 1 week after inoculation, wilt symptoms were observed except on control plants. Koch's postulates were fulfilled by reisolation of P. cucumerina from the browned vascular tissues of inoculated plants. To the best of our knowledge, this is the first report of kimchi cabbage wilt caused by P. cucumerina in Korea. It is believed that this will be helpful in research on the management of kimchi cabbage wilt disease.

Soybean (Glycine max L.) is an economically important legume crop in South Korea (Lee and Ahn 2017; Chae et al. 2025; Cho and Yoon 2025). In October 2021, anthracnose symptoms were observed on soybean plants in two commercial (1 ha each) fields in Gimje, Jeollabuk-do, South Korea (35°80′N, 126°88′E), with disease incidence exceeding 30%. Symptoms consisted of irregular, dark brown necrotic lesions surrounded by yellow chlorotic halos on leaves. Six symptomatic leaves were collected from the two fields for pathogen isolation. Small pieces (approximately 5 × 5 mm), surface-disinfested tissues from lesion margins were plated on water agar amended with streptomycin. Five isolates (FD0006, FD0007, FD8, FD0033, and FD34) were obtained and purified on potato dextrose agar (PDA). Colonies were pale gray with entire margins after 7 days at 25°C. Conidia (n = 50) were hyaline, aseptate, cylindrical with rounded ends, measuring 14.4–21.0 × 4.1–6.2 μm (mean 16.4 × 5.3 μm). Appressoria were dark brown, irregular to strongly lobed, measuring 7.4–15.9 × 4.7–11.3 μm (mean 11.7 × 8.2 μm). Asci were cylindrical to clavate, 38.0–70.4 × 6.5–14.2 μm, and ascospores were hyaline, aseptate, and 13.5–22.1 × 4.6–6.8 μm. These characteristics were consistent with species of the Colletotrichum orchidearum species complex, including C. reniforme (Liu et al. 2022; Zhao et al. 2026). For molecular identification, partial sequences of gapdh, chs-1, act, tub2, and his3 were amplified and sequenced using primers described by Damm et al. (2019). Representative sequences were deposited in GenBank (gapdh: LC797748–LC797752; tub2: LC797788–LC797792; chs-1: LC797828–LC797832; act: LC797868–LC797872; his3: LC797906–LC797910). Multilocus phylogenetic analysis (Bayesian and Maximum Likelihood) of the combined dataset placed all five isolates within the C. reniforme clade with strong support. Pathogenicity was assessed using isolates FD0007 and FD00034 on four soybean plants (cv. Daewon and Cheongja 5) at the V2–V3 growth stage. Plants were inoculated by spraying approximately 10 mL of a conidial suspension (1 × 10 6 conidia/mL) containing 0.02% Tween 20 onto unwounded leaves until runoff. Control plants (four) were sprayed with sterile distilled water containing 0.02% Tween 20. After inoculation, plants were maintained in a dew chamber at 24°C in the dark for 24 h and then transferred to a greenhouse, where they were kept at approximately 95% relative humidity by enclosing the plants with plastic film. Necrotic lesions similar to those observed in the field developed within six days, with an 80% disease incidence. The fungus was reisolated from symptomatic tissues and identified as C. reniforme based on morphological and molecular characteristics described above, thereby fulfilling Koch’s postulates. The experiment was repeated twice with similar results. Colletotrichum reniforme was originally described from China as a member of the C. orchidearum species complex (Liu et al. 2022). To our knowledge, this is the first report of soybean anthracnose caused by C. reniforme and the first record of this species in South Korea. This finding expands the known geographic distribution and host range of C. reniforme and indicates that the pathogen may represent an emerging threat to soybean production in Korea. Accurate identification of Colletotrichum species associated with soybean anthracnose will be important for disease surveillance, epidemiological studies, and the development of effective management strategies.

A comprehensive survey of field-isolated Fusarium fujikuroi populations was conducted to evaluate their sensitivity to the quinone outside inhibitor (QoI) orysastrobin. The assessment revealed widespread insensitivity to this fungicide, whereas canonical resistance-conferring mutations in the target cytochrome b (cytb) gene were absent in the representative isolates examined. To clarify the non-target site resistance (NTSR) mechanisms driving this phenomenon, we identified a novel Zn2Cys6 transcription factor, FFUJ_00276 (designated as RARF1, Respiration Associated Regulatory Factor 1), which was transcriptionally induced upon orysastrobin exposure. Functional characterization via CRISPR-Cpf1-mediated gene deletion demonstrated that Δrarf1 mutants exhibited increased susceptibility to both QoI and succinate dehydrogenase inhibitor (SDHI) fungicides. In planta assays indicated that while RARF1 is dispensable for fungal pathogenicity, it is required to sustain orysastrobin resistance during host infection. Comparative transcriptomic analysis revealed that the loss of RARF1 resulted in the coordinated downregulation of genes governing ribosome biogenesis and mitochondrial oxidative phosphorylation. Simultaneously, orysastrobin treatment triggered the upregulation of multiple ATP-binding cassette (ABC) and major facilitator superfamily (MFS) transporters. These results establish RARF1 as a key regulatory component governing fundamental cellular bioenergetics under fungicidal stress. Importantly, this study provides a pioneering framework for exploring QoI NTSR mechanisms and highlights RARF1 as a promising molecular target for managing resistance in F. fujikuroi.

In June 2025, celery (Apium graveolens) plants showing wilting and crown rot were collected from commercial fields in Taebaek, Korea. Six oomycete isolates were recovered from symptomatic roots, crowns, and stalks. Based on morphological and cultural characteristics, together with sequence analyses of the internal transcribed spacer (ITS) and cytochrome c oxidase subunit I (cox1) regions, the isolates were identified as Phytophthora tentaculata. Temperature-dependent growth assays on V8 agar (V8A) revealed that all isolates exhibited optimal mycelial growth at 20-25°C, with minimum and maximum growth temperatures of 10°C and 30°C, respectively. Sporangium production varied markedly among culture media and was highest on water agar, followed by 5% V8A, whereas higher V8 concentrations strongly suppressed sporulation. Pathogenicity tests conducted using mycelial plug inoculation resulted in stalk rot, wilting, and plant collapse on celery, consistent with field symptoms. The pathogen was successfully reisolated from symptomatic tissues, whereas no Phytophthora species were recovered from mock-inoculated controls, thereby fulfilling Koch's postulates. This study represents the first integrated biological and pathological characterization of P. tentaculata associated with celery blight in Korea and provides essential information for accurate diagnosis and improved disease management.

Apple bitter rot is a significant fungal disease affecting apple (Malus domestica) orchards globally, including South Korea, and is known for causing severe yield losses and economic damage in apple orchards. In the summer of 2023, apple fruits (cv. Hongro) exhibiting typical bitter rot symptoms were collected from orchards in Jangsu, Korea (GPS: 35.625260° N, 127.516693° E). The Disease incidence ranged from 30% to 40% across 2 surveyed orchards. Infected apple fruits exhibited initial symptoms of small, circular, sunken lesions. Under humid conditions, pink to orange spore masses were visible on the lesion surface. Lesions were excised, surface-sterilized, and cultured on potato dextrose agar (PDA) to isolate the causal agent. Pure cultures were obtained by single-spore isolation. A total of four Colletotrichum isolates were obtained from the four affected fruits. Morphologically, seven-day old colonies on PDA (incubated at 25°C in the dark) were gray to pale pink with a cottony texture, and conidia were cylindrical to fusiform, measuring 12.6 - 18.6 × 3.9 - 6.3 μm (mean ± SD, 14.6 ± 1.4 × 5.1 ± 0.5 μm, n = 70), hyaline, and smooth-walled. Appressoria were dark brown, round to oval, measuring 7.0 - 12.9 × 5.5 - 10.2 μm (mean ± SD, 9.3 ± 1.3 × 6.9 ± 1.9 μm, n = 70). The morphological characteristics of the present isolates align with those of Colletotrichum species within the Colletotrichum acutatum species complex, including C. orientalis and C. fioriniae (Damm et al. 2012; Chen et al. 2022). The molecular identification involved PCR amplification and sequencing of the ITS, GAPDH, TUB, ACT, CHS-1, and HIS3 using ITS1/ITS4, GDF1/GDR1, T1/Bt2b, ACT 512F/ ACT-783R, CHS-79F/CHS-345R, and CYLH3F/CYLH3R, respectively (Damm et al. 2012). The resulting sequences were deposited in NCBI with GenBank accession numbers LC863958 to LC863977. The maximum likelihood tree was constructed based on the concatenated ITS, GAPDH, TUB, ACT, CHS-1, and HIS3 sequences using MEGA X software. The phylogenetic tree positioned three isolates within the C. orientalis clade and one isolate within the C. fioriniae clade. Pathogenicity tests were conducted by inoculating either wounded apple (a wound made with sterile pin) or un-wounded apple surface sterilized healthy fruits with the spore suspension (1 × 106 conidia/mL) of the isolates. Control fruits were mock-inoculated with sterile water. Fruits were incubated in a plastic box at 25°C with high humidity. Symptoms identical to those observed in the field developed on inoculated fruits within 7 d, while control and un-wounded fruits remained symptomless. C. orientalis was re-isolated and identified from the lesions, fulfilling Koch's postulates. Seven healthy fruits (cv. Hongro) were used per treatment, and the experiment was repeated twice. In Korea, Colletotrichum species associated with apple bitter rot include C. gloeosporioides, C. aenigma, C. acutatum, C. fructicola, C. fioriniae, C. gloeosporioides, C. greavilleae, C. nymphaeae, and C. siamense (Oo et al. 2018; Kim et al. 2022; Lee et al. 2021; Nam et al. 2024). To the best of our knowledge, this is the first report of apple bitter rot caused by C. orientalis in South Korea. The outcome highlights the need for vigilant monitoring and help to develop integrated disease management practices to deal with C. orientalis.

Verticillium wilt is an emerging threat to Brassicaceae crops worldwide, yet information on the species diversity and pathogenicity of Verticillium on Napa cabbage (Brassica rapa subsp. pekinensis) in South Korea remains limited. During surveys in 2020 and 2021, patches of wilted Napa cabbage plants were observed in highland cultivation regions, with disease incidence ranging from 1 to 10%. Twenty symptomatic plants were collected, and fifteen fungal isolates were obtained through tissue culture. Morphological observations and multilocus phylogenetic analyses based on four loci (ACT, EF, GPD, and TS) identified two species, V. dahliae and Verticillium longisporum (lineages A1/D1). Morphologically, V. longisporum produced longer conidia (>6.1 μm) and elongate microsclerotia, whereas V. dahliae produced shorter conidia (<6.0 μm) and spherical microsclerotia. Growth assays demonstrated that V. longisporum grew optimally at 22 °C and V. dahliae at 25 °C, with V8 agar supporting the best growth of both species. Pathogenicity tests on Napa cabbage seedlings confirmed that both species caused typical wilt symptoms, including leaf yellowing, senescence, and stunted growth. To our knowledge, this is the first report of V. longisporum associated with Verticillium wilt of Napa cabbage in South Korea. While Verticillium wilt has so far been confined to highland cultivation areas, considering the predominance of V. longisporum in autumn-winter cropping regions in Japan, continued monitoring in similar Korean production regions will be essential. These findings provide new insights into the distribution, morphology, and pathogenicity of Verticillium species, contributing to the development of effective management strategies for Napa cabbage production.

Fire blight and black shoot blight diseases, caused by Erwinia amylovora and Erwinia pyrifoliae, respectively, continue to spread several areas in Korea, despite intensive efforts by the government to control diseases. The distribution pattern of fire blight and black shoot blight is different from each other in Korea. Consequently, it is required to investigate the pathogenicity of E. amylovora and E. pyrifoliae in apple trees. The disease severity of fire blight and black shoot blight was compared in this study by an artificial inoculation of E. amylovora and E. pyrifoliae suspensions into the abaxial veins of apple leaves and measuring their pathogenicity at varying temperatures. Furthermore, disease severity was assessed by inoculating E. amylovora and E. pyrifoliae in apple flowers and assessing their pathogenicity at various temperatures. The E. amylovora-inoculated flowers displayed greater disease index than E. pyrifoliae-inoculated flowers at temperatures ranging from 18°C to 25°C. Upon examining the population sizes of E amylovora and E. pyrifoliae in flowers using a real-time polymerase chain reaction (PCR), the Ct value of E. amylovora was found to be lower in the style including stigma and hypanthium than the Ct value of E. pyrifoliae, except at 18°C. Hypanthium contained E. amylovora TS3128 and E. pyrifoliae YKB12327 at >107 and 105 CFU/mL, respectively at 15°C. Furthermore, in this study, we investigated the population size of E. amylovora and E. pyrifoliae in apple flowers in relation to temperature in order to clarify the differences in their pathogenicity.

This report presents a compilation of plant disease occurrences in Korea based on field observations conducted by members of the Field Research Committee of the Korean Society of Plant Pathology in 2025. The dataset documents cases of emerging and recurrent diseases—including soil-borne pathogens, viral complexes, and foliar diseases—reported from various agricultural regions where committee members carried out surveys. Although the records do not constitute a comprehensive national survey, they provide georeferenced, metadata-rich occurrence information that serves as a useful reference for identifying when and where specific diseases were observed. These findings also reflect broader trends in disease emergence under variable climate conditions and highlight the value of continued field-based monitoring to support predictive modeling, risk assessment, and evidence-based plant disease management in Korea.

Fig (Ficus carica L.) belonging to the Moraceae family is cultivated worldwide, with its primary production areas located in the Mediterranean region (Tous and Fergusen 1996). Yeongam-gun is a significant region for fig cultivation in Korea, accounting for 42% of the country's total fig cultivation area with approximately 1,400 fields (453ha, production yield 6000 tons). In July to November 2023, we observed severe rust disease in four fig orchards in Yeongam-gun (34°42'52.2"N, 126°31'32.16"E). The disease had affected 70% of the fig cultivation area (cv. Masui Dauphine). The area of each field is approximately 0.33~0.66ha, and 5 samples were collected from each field. Pustules of the pathogen were found in all samples. The diseased plants were deposited in the herbarium of the National Institute of Agricultural Sciences, Wanju, Korea (Specimen No. Cero_001). The initial symptoms were observed as chlorotic spots on the adaxial surface of the leaves, which developed into necrotic areas surrounded by chlorotic halos. Over time, dark brown spots were observed on the adaxial surface of the leaves, and abundant reddish-brown pustules were visible on the abaxial surface. Almost all leaves with these symptoms fell prematurely. Microscopic observation revealed that the urediniospores (n>50) were ellipsoidal, globose, obovoidal, or angular in shape, yellowish to faintly orange in color, sized 19.5-39.9 × 10.1-27.5 μm and had a wall thickness of 0.6-1.5 μm (average 1 μm). Telia were not observed. These morphological characteristics were comparable with that of Cerotelium fici (Gardner, 1997; Latinovic et al., 2015). For molecular analysis, genomic DNA was extracted from 3 to 5 samples, and the internal transcribed spacer region 2 (ITS2) and the large subunit (LSU) were amplified and sequenced using primer set: Rust2inv (Aime, 2006) and LR6 (Vilgalys and Hester, 1990). Furthermore, approximately 660 bp of the cytochrome c oxidase subunit III (COX3) gene was amplified and sequenced with CO3_F1 and CO3_R1 primers (Vialle et al., 2009). The obtained sequences were deposited in NCBI GenBank (GenBank accession no. PP491072 to PP491074 and PP491079 to PP491081). Phylogenetic tree analysis using the maximum likelihood method identified the isolate as Cerotelium fici. Pathogenicity test was conducted either by placing or by rubbing symptomatic leaf pieces on healthy leaves (5 leaves/plant) of three-year-olds fig plants (cv. Masui Dauphine) in a greenhouse in Wanju-gun, Jeonbuk special self-governing province. Healthy and symptom free leaf pieces were used for control. Two plants per treatment were used and the experiment repeated twice. The typical symptoms of fig rust disease were observed two weeks after inoculation in both methods. Control leaves were symptomless. C. fici was successfully reidentified from symptomatic tissues of inoculated leaves, fulfilling Koch's postulates and confirmed as a causal agent of fig rust. Fig rust caused by C. fici has been reported in New Zealand, Montenegro, Hawaii and other tropical regions (McKenzie, 1986). To our knowledge, this is the first report of fig rust in Korea caused by Cerotelium fici. It is believed that this will be helpful in research on the management of fig rust disease.

We have developed FBcastS (Fire Blight Forecasting System), a cloud-based information system that leverages the K-Maryblyt forecasting model. The FBcastS provides an optimal timing for spraying antibiotics to prevent flower infection caused by Erwinia amylovora and forecasts the onset of disease symptoms to assist in scheduling field scouting activities. FBcastS comprises four discrete subsystems tailored to specific functionalities: meteorological data acquisition and processing, execution of the K-Maryblyt model, distribution of web-based information, and dissemination of spray timing notifications. The meteorological data acquisition subsystem gathers both observed and forecasted weather data from 1,583 sites across South Korea, including 761 apple or pear orchards where automated weather stations are installed for fire blight forecast. This subsystem also performs post-processing tasks such as quality control and data conversion. The model execution subsystem operates the K-Maryblyt model and stores its results in a database. The web-based service subsystem offers an array of internet-based services, including weather monitoring, mobile services for forecasting fire blight infection and symptoms, and nationwide fire blight monitoring. The final subsystem issues timely notifications of fire blight spray timing alert to growers based on forecasts from the K-Maryblyt model, blossom status, pesticide types, and field conditions, following guidelines set by the Rural Development Administration. FBcastS epitomizes a smart agriculture internet of things (IoT) by utilizing densely collected data with a spatial resolution of approximately 4.25 km to improve the accuracy of fire blight forecasts. The system’s internet-based services ensure high accessibility and utility, making it a vital tool in data-driven smart agricultural practices.

Amaranth (Amaranthus spp. L) is not native to South Korea but is cultivated in small scales for ornamental purposes as well as leafy vegetables and pseudo cereals. In this study, a new species within the genus Fusarium was isolated from amaranth, showing stem rot symptoms from a farmer field in Hwaseong, South Korea. The disease is characterized by dark-brown spots with black borders, leading to withering. Phylogenetic analysis-based concatenated sequences of translation elongation factor 1-alpha (TEF1), beta-tubulin (tub2), calmodulin (cmdA), RNA polymerase largest subunit (RPB1), and RNA polymerase II second largest subunit (RPB2) genes revealed that the obtained isolates formed a distinct clad within the Fusarium fujikuroi species complex and is closely related to F. circinatum. Cultural and morphological characteristics and pathogenicity on healthy amaranth plants (stem and leaves) were examined. The isolates readily differentiated from F. circinatum based on one- to five-septate macroconidia and the absence of sterile hyphae. Based on molecular and morphological characteristics, this fungus is demonstrated to be a new species and is described here as F. amaranthi, the causal agent of stem rot of amaranth in South Korea.

Since 2009, the Korean Society of Plant Pathology has established the Committee on Common Names of Plant Disease to systematically review and determine plant disease names and related terminologies. The committee published the 6th edition of the List of Plant Diseases in Korea (LPDK) in 2022, and the list has been made publicly accessible online. The online database has significantly enhanced user accessibility, expedited update processes, and improved interoperability with other databases. As a result, the 6.1 edition of the list was released by online LPDK in 2023, detailing new disease names added over the preceding year and revisions to existing names. Subsequently, in 2024, the 6.2 edition was published, encompassing 6,765 diseases caused by 2,503 pathogen taxa across 1,432 host species. The public release of the online database has, however, introduced several challenges and tasks. Addressing these issues necessitates the development of modern, standardized nomenclature guidelines and a robust system for the registration of new disease names. Open communication and collaboration among the diverse members of the Korean Society of Plant Pathology are required to ensure the reliability of the LPDK.

Anthracnose, a destructive fungal disease, poses a significant threat to chili pepper (Capsicum annuum L.) production worldwide (de Silva et al. 2019). In South Korea, anthracnose outbreaks have traditionally been attributed to several Colletotrichum species such as C. gloeosporioides and C. acutatum. About 10% of the yield (chili production) is lost annually in South Korea due to chili anthracnose (Oo et al. 2020). During field surveys conducted in August 2017, symptomatic lesions resembling anthracnose were observed on chili pepper in two farmer's fields (Gochang and Cheongyang) in South Korea. Affected fruits exhibited characteristic symptoms, including circular sunken lesions with dark margins and abundant orange spore masses on the surface. About 20% of chili pepper fruit were affected in each field with an area of about 0.2 ha. Five putative Colletotrichum spp. isolates were obtained from six affected fruits (three from each field) following the procedure described by Cai et el. (2009). Three isolates (C01049, C01111, and C01115), representing each location, were selected to identify at the species level. Colonies on potato dextrose agar (incubated at 25°C in the dark for 7 days) were cottony with entire margins, white aerial mycelium and dark gray in the center. Conidia were hyaline, aseptate, cylindrical with bothnds round, and 17.8 - 30.5 × 6.0 -10.0 µm (mean 23.8 ×7.9 μm, n = 30). Appressoria were dark brown, irregular but mostly ovoid with smooth walls. These morphological features align with those of Colletotrichum spp. within the Colletotrichum gigasporum species (Liu et al. 2014). The identity of the pathogen was further confirmed through multi-locus phylogenetic analysis. The target genes including ITS, ACT, CHS-1, GAPDH, TUB2, and GS were amplified and sequenced using the primer sets ITS1/ITS4, ACT 512F/ ACT-783R, CHS-79F/ CHS-345R, GDF/GDR, T1/Bt2b, and GSF1/GSR1, respectively (Weir et al. 2012; Liu et al. 2014). The resulting sequences were deposited in GenBank (accession no: ITS: MT605261, MT605262, LC823714; ACT: MT612991, MT612992, LC823718; CHS-1: MT612993, MT612994, LC823717; GAPDH: LC811375, LC811376, LC823716; TUB2: MT612997, MT612998, LC823715; GS: LC811377, LC811378, LC823719). The constructed Bayesian and maximum likelihood tree based on combined sequences of ITS, ACT, CHS-1, GAPDH, TUB2, and GS confirmed the identification of the isolates (C01049, C01111, C01115) as C. gigasporum. Pathogenicity tests were conducted by inoculating healthy chili fruit with 70 µL of a conidial suspension (1×106 conidia /mL) of pure cultures of the isolates. The conidial suspension was applied on 10 wounded or 10 non-wounded fruit. The same number of fruit were treated with sterile distilled water as controls. Within 5 days of inoculation, symptoms consistent with anthracnose developed on the inoculated wounded fruit, whereas non-wounded and control fruit remained asymptomatic. This experiment was repeated twice. Colletotrichum gigasporum was re-isolated from diseased tissue of inoculated fruit. Colletotrichum gigasporum has been identified as the cause of anthracnose on Dalbergia odorifera, Carica papaya in China, and Brassica oleracea in India (Wan et al., 2018; Saini et al. 2022; He et al. 2023). To the best of our knowledge, this report marks the first documented instance of C. gigasporum causing anthracnose of chili pepper in South Korea. These results indicate that various species of Colletotrichum can be the fungi causing chili pepper anthracnose. The findings of this study emphasize the need for effective disease management strategies to mitigate impact of C. gigasporum on chili pepper cultivation in the region.

Since its initial outbreak in Korea in 2015, fire blight has consistently emerged annually. Fire blight outbreaks usually begin in May, peak in June, and decline in July in Korea. In this study, we analyzed cases that exhibit a distinct pattern of disease occurrence based on yearly weather conditions from 2020 to 2023. In 2020, fire bight disease occurrence began in late May. Although the disease incidence started late by the low temperatures in April, which caused flowering period delayed, the incidence increased significantly due to the high risk of blossom infection. In 2021, the first outbreak began in late April because the flower infection started in early April. In 2022, despite the high blossom infection risk during the flowering period in April and the high incidence of fire blight in May, the incidence decreased sharply from June due to the low rainfall in May. In 2023, due to torrential rains and hail in late June, the incidence of fire blight increased even in July. Considering the weather factors that affect the increase of fire blight disease, it is suggested that control measures to prevent the fire blight infection should be carried out before and after wind-driven rains.

Narrow-head ragwort (Ligularia stenocephala (Maxim.) Matsum. & Koidz.) has been used for medicinal purposes and a leafy vegetable in South Korea (Choi et al., 2007; Debnath et al., 2017). In May 2022, brown spots and blight were observed on the leaves in a farmer's field in Namwon (35°26'58.9"N, 127°28'55.9"E), Korea. About 80% of the plants in a 3000 m2 cultivation area were infected. To isolate the causal agent, small pieces (1 mm2) surface-sterilized (1% NaOCl for 1 min) symptomatic leaf tissues were put onto a water agar (WA) plate and incubated in the dark at 25℃. After five days of incubation, two isolates (FD00021, FD00022) were obtained from diseased leaves using a single spore isolation technique. Morphological characteristics were examined after seven days of incubation at 25℃ in the dark. Colonies were 51.6 to 65.3 mm in diameter, gray-green in the center, and ivory at the edge. Conidiophores were straight or curved and 10 - 34 × 4 - 5 μm. Conidia were solitary or two to four in a chain, long ellipsoid to obclavate, one to thirteen transverse septa, 52 - 169 ×14 - 34 μm, blunt-tapered beak variable in size 4 - 56 × 3 - 10 μm (n=75). The morphological and cultural characteristics of the isolates were consistent with that of Alternaria cinerariae (Nishikawa and Nakashima, 2015; Simmons, 2007). For molecular identification, genomic DNA was extracted from 5-day-old cultures using the Maxwell® RSC PureFood GMO and Authentication Kit (Promega). Five gene regions, including rDNA ITS, GPD, Alt a, RPB2, and EF1-α were amplified and sequenced using ITS1/ITS4, gpd1/gpd2, Alt-a1-for/ Alt-a1-rev, RPB2-5F2/RPB2-7cR, and EF1-728F/EF1-986R primer sets respectively (Wang et al., 2022; Garibaldi et al., 2022). The resulting sequences were deposited in GenBank with accession no. OP785152, OP785153 and OP832000 to OP832007). The concatenated genes (rDNA ITS, GPD, Alt a, RPB2, and EF1-α) sequence identity of the FD00021 and FD00022 against the reference strain A. cinerariae CBS 116495 is 99.92% (2572/2574) and 99.84% (2570/2574), respectively. Maximum Likelihood tree was inferred based on the concatenated sequences of the five gene regions using the Kimura 2-parameter model with 1,000 bootstrap replications. The phylogenetic tree showed that the present strains and A. cinerariae CBS 116495 fell into the same clade with high bootstrap support (100%). Based on morphological characteristics and molecular analysis, the isolates were identified as A. cinerariae. To confirm their pathogenicity, drops (70 μl) of conidial suspension (1×104 spores/ml) were applied on intact healthy leaves (3 leaves/plant) of plants (3 plants/isolate) that had been cultivated for one month after transplantation as seedlings. Controls were treated with sterile distilled water. The treated plants were covered with plastic boxes to maintain humidity around 90% and were maintained in an incubator at 25℃ in a 12-hour light-dark cycle. Symptoms appeared only on inoculated leaves after four days of inoculation, while controls remained asymptomatic. The A. cinerariae isolates were re-isolated from infected tissue of the inoculated leaves, thus fulfilling Koch's postulates. Alternaria cinerariae is an important plant pathogen that can cause leaf spot and blight on a variety of host plants including Cineraria spp. and Tussilago farfara (He et al. 2020). This is the first report on leaf spot on Narrow-head ragwort caused by A. cinerariae in the world. Leaf spot disease caused by Alternaria cinerariae is a significant threat to narrow-head ragwort agriculture in South Korea. Therefore, its control strategies are necessary for increasing productivity.

Chili (Capsicum annuum L.) is an economically important crop worldwide, valued for its culinary uses. In South Korea, anthracnose caused by Colletotrichum spp. including C. truncatum, C. gloeosporioides, C. coccodes, C. acutatum, and C. scovillei incurs on substantial economic loss (Kim et al. 2008; Oo and Oh 2020). In August 2022, somewhat different types of symptoms that was not typical on chilli fruits were observed in a field in Yereonggwang (GPS: 35.2579° N, 126.4742° E), South Korea. The disease symptoms appeared as sunken, necrotic lesions with dense black spore masses forming in concentric rings. The estimated disease incidence the 0.2 ha field showing up to 1% of fruits affected. To isolate the pathogen, six symptomatic chilli fruits were collected. Small pieces (5 mm²) were cut from the margins of the lesions, surface-sterilized in 70% ethanol for 30 sec, followed by 1% sodium hypochlorite for 1 minute, and then rinsed three times in sterile distilled water. The tissue pieces were placed on potato dextrose agar (PDA) plates and incubated at 25°C in the dark. After 3 to 5 days, emerging fungal colonies were sub-cultured to obtain pure isolates. A total of five isolates were obtained and initially identified as Colletotrichum spp. based on morphological characteristics. Seven-day old colonies were initially white, turning light orange with age on PDA. Setae (observed on lesion) were dark brown, verruculose and septate. Conidia were cylindrical, hyaline, and measured 14.8 to 19.9 × 4.2 to 6.5 µm (mean 16.7 × 5.6 μm, n = 70) in size; appressoria were brown to dark brown and irregularly shaped. These morphological characteristics of the isolates agree with those reported for the morphology of C. sojae by Damm et al. (2019). To confirm the identity of the isolates, DNA was extracted and specific gene regions were amplified and sequenced using the following primer sets: ITS (ITS1 and ITS4), GAPDH (GDF1 and GDR1), ACT (ACT-512F and ACT-783R), TUB (T1 and Bt2b), HIS3 (CYLH3F and CYLH3R), and CHS-1 (CHS-79F and CHS-345R). The resulting sequences were deposited in the NCBI GenBank with accession numbers (LC830742 to LC830766). Maximum likelihood phylogenetic analysis using combine sequences of ITS, GAPDH, ACT, TUB, HIS3 and CHS-1 in MEGA X confirmed the isolates as C. sojae, marking the first report of this pathogen on chilli in South Korea, previously known to infect soybean. Pathogenicity tests were conducted on wound and nonwounded healthy and mature-green chili fruits (cv. Bicksita) to confirm the pathogenicity of the isolated C. sojae. The fruits were surface-sterilized using 70% ethanol and then rinsed with sterile distilled water. The fruits were wounded using a sterile needle to facilitate infection. A conidial suspension (1x106 conidia/mL) was prepared from 7-day-old PDA cultures. Each fruit was inoculated by placing a 10 µL drop of the conidial suspension onto the wounded and nonwounded sites (4 to 5) of the wound and unwound fruits, respectively. Control fruits were inoculated with sterile water. A total of 40 fruits per treatment were used and the experiment repeated twice. The fruits were placed in plastic box lined with moist paper towels to maintain high humidity and incubated at 25°C. Anthracnose symptoms developed on the inoculated fruits within 7 days, while control and unwounded fruits remained symptom-free. Colletotrichum sojae was successfully reisolated from the symptomatic fruits, fulfilling Koch’s postulates and confirming its role as the causal agent of the disease. Colletotrichum sojae is known to infect Fabaceae species worldwide such as Glycine max, Medicago sativa, Phaseolus vulgaris, Atractylodes ovata and Vigna unguiculata (Damm et al. 2019; Talhinhas and Baroncelli 2021), Atractylodes ovata in South Korea (Hassan et al. 2021) and chili pepper in China (Zhanget al. 2023). The first report of C. sojae causing chili anthracnose in South Korea represents a new challenge for chili growers. Integrated disease management strategies need to be developed and implemented to mitigate its impact.

Erwinia amylovora is a gram-negative plant pathogen that causes fire blight in apple and pear trees, resulting in significant damage worldwide. In this study, we monitored the emergence of fire blight from 2019 to 2023 to determine the emergence patterns and the factors affecting the outbreak of the disease. As a result of the 5-year survey on the emergence of fire blight, a total of 2,029 cases have emerged, mostly in apple trees of 1,378 cases (67.9%) followed by 645 cases (31.8%) in pear trees, and from quince, hawthorn, and mountain ash trees. Fire blight appeared in specific areas of Gyeonggi, Chungnam, Gangwon, and Chungbuk provinces in 2019, but spread to Andong and Yesan in 2021, Muju and Bonghwa in 2023. In 2020 and 2021, there were 744 and 618 cases of fire blight outbreaks, respectively, compared to other years (188–245 cases/year). Notably, 914 of these cases were observed in apple trees from May to July, with 667 cases reported in Chungju and Jecheon. The incidence of fire blight was positively correlated with the daily maximum temperatures and rainy days in January and February, as well as the rainy days in May and June. The average age of the diseased pear trees was 25 years, higher than the 10-year average age of the apple trees. This study provides fundamental information to understand the status and factors affecting the fire blight emergence in Korea. Prevention measures should be established through continuous analysis of the status of fire blight.

Erwinia pyrifoliae is a necrotrophic pathogen that causes black shoot blight in Asian (Nashi) pears. Black shoot blight was first observed in pear trees in Korea in 1995. E. pyrifoliae has only been detected in apple, and pear trees in Korea and strawberries in the Netherlands. E. amylovora, a pathogen related to E. pyrifoliae, is known to cause diseases of Rosaceae plants, but the susceptibility to black shoot blight have not been examined. Planted or naturally growing Rosaceae plants were investigated in 31 sites where black shoot blight occurred in the past from the central region of Korea. As a result, 47 kinds of plants included in 20 genera were observed. Among them, there are 38 woody plants and nine herbaceous plants. The susceptibility to black shoot blight was examined with 14 species in seven genera of the Rosaceae plants by artificial inoculation. After 5 days, the symptoms were observed at the inoculated site and were re-isolated bacteria from lesions of inoculated plants and confirmed by observing morphological characteristics on King’s Medium B’s medium. The bacterial isolates were further identified using real-time polymerase chain reaction using a HelixDtect EAEP detection kit. A total of 12 species of Rosaceae plants showed disease symptoms of black shoot blight, and fire blight has been shown to cause disease symptoms in a total of 11 species of Rosaceae plants. In this study, host plants of Rosaceae plants for black shoot blight were investigated, and these results can be used to monitor the occurrence of black shoot blight.