• The Plant Pathology Journal
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• v.40 no.1
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• pp.59-72
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• 2024

A comprehensive survey of mungbean-growing areas was conducted to observe leaf spot disease caused by Alternaria alternata. Alternaria leaf spot symptoms were observed on the leaves. Diversity of 50 genotypes of mungbean was assessed against A. alternata and data on pathological traits was subjected to cluster analysis. The results showed that genotypes of mungbean were grouped into four clusters based on resistance parameters under the influence of disease. The principal component biplot demonstrated that all the disease-related parameters (% disease incidence, % disease intensity, lesion area, and % of infection) were strongly correlated with each other. Alt a 1 gene that is precisely found in Alternaria species and is responsible for virulence and pathogenicity. Alt a 1 gene was amplified using gene specific primers. The isolated pathogen produced similar symptoms when inoculated on mungbean and tobacco. The sequence analysis of the internal transcribed spacer (ITS) region, a 600 bp fragment amplified using specific primers, ITS1 and ITS2 showed 100% identity with A. alternata. Potato virus X (PVX) -based silencing vector expressing Alt a 1 gene was constructed to control this pathogen through RNA interference in tobacco. Out of 50 inoculated plants, 9 showed delayed onset of disease. Furthermore, to confirm our findings at molecular level semi-quantitative reverse transcriptase polymerase chain reaction was used. Both phenotypic and molecular investigation indicated that RNAi induced through the VIGS vector was efficacious in resisting the pathogen in the model host, Tobacco (Nicotiana tabacum). To the best of our knowledge, this study has been reported for the first time.

• Research in Plant Disease
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• v.12 no.2
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• pp.103-107
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• 2006

An array of surveys was designed to improve current Pesticide Management Law and Acts by investigating farmers' usage of pesticides and by assessing applicability of Plant Protection Certificate to register local pesticide markets or related businesses. This study indicates that most farmers choose pesticide recommended by local pesticide market dealers. This survey also indicates serious misuse or overuse of pesticides by farmers probably due to inappropriate recommendations. To guarantee rational use of pesticides by the end users, most experts in the plant protection areas have realized the importance of the Certificate as a license to register the local pesticide markets. To the end, current Pesticide Management Laws and Acts need to be revised to ask pesticide-dealing workers to take the Plant Protection Certificate.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.97-102
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• 2006

A virus causing vein banding, sometimes yellow mosaic and rugose symptoms on peanut was prevalent around Suwon, Korea. A survey conducted in the area found disease incidence, depending on cultivar, to range from 79 to $100\%$. The virus was found to be seed-transmissible in all the five peanut cultivars tested with transmission rates ranging from 2 to $16\%$. Host range analysis failed to differentiate 9 field isolates collected from different peanuts cultivars showing various symptoms. Inclusion bodies such as scroll, pinwheel and long laminated aggregates induced by the virus in host plant cells were similar to those induced by members of the Potyvirus subdivision III. The virus showed < $95\%$ homology with Bean common mosaic virus (BCMV), BCMV-BICMV/AzMV strains and only < $91\%$ with Desmodium mosaic virus. Based on biological characterization, electron microscopy and molecular analyses of a Korean isolate (Daewon 1), the virus was identified as peanut stripe strain of BCMV.

• Mycobiology
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• v.35 no.4
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• pp.235-237
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• 2007

Leaf blight and bulb rot symptoms were observed on narcissus plants grown in Yongin, Cheongwon and Namhae areas in Korea during disease survey from 1999 to 2002. A total of 15 isolates of Botrytis sp. were obtained from the infected plant parts of narcissus. All the isolates were identified as Botrytis narcissicola based on their morphological and cultural characteristics. Three isolates of B. narcissicola were tested for their pathogenicity to leaves and bulbs of narcissus by artificial inoculation. All the isolates induced leaf blight and bulb rot symptoms on the plants of narcissus by artificial inoculation. The symptoms induced by artificial inoculation were similar to those observed in the fields. This is the first report of narcissus smoulder caused by B. narcissicola in Korea.

• Research in Plant Disease
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• v.24 no.4
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• pp.348-352
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• 2018

A multiplex reverse transcription-polymerase chain reaction (mRT-PCR) assay was developed for the detection of Clover yellow vein virus (ClYVV), Peanut mottle virus (PeMoV), and Tomato spotted wilt virus (TSWV), which were recently reported to infect soybean and azuki bean in Korea. Species-specific primer sets were designed for the detection of each virus, and their specificity and sensitivity were tested using mixed primer sets. From among the designed primer sets, two combinations were selected and further evaluated to estimate the detection limits of uniplex, duplex, and multiplex RT-PCR. The multiplex RT-PCR assay could be a useful tool for the field survey of plant viruses and the rapid detection of ClYVV, PeMoV, and TSWV in leguminous plants.

• The Korean Journal of Mycology
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• v.50 no.4
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• pp.357-360
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• 2022

In July 2021, we surveyed diseases affecting wild vegetables grown in Hongcheon, Gangwon Province, Korea. During this survey, we observed severe seedling rot symptoms in Kamchatka goatsbeard (Aruncus dioicus) grown in a vinyl greenhouse. The incidence of the disease in the plant seedlings was 1-10%. Diseased seedlings from this population were collected, and fungi were isolated from leaf and petiole lesions. Rhizoctonia sp. was consistently isolated from the lesions. We examined the morphological and cultural characteristics and anastomosis groups of nine Rhizoctonia sp. isolates obtained from the lesions. The results revealed that all isolates corresponded to Rhizoctonia solani AG-1(IB). Three isolates of R. solani AG-1( IB) were evaluated to determine their pathogenicity towards Kamchatka goatsbeard seedlings through artificial inoculation. The tested isolates caused rot symptoms on the inoculated plant seedlings. The symptoms were similar to those observed in plant seedlings from the vinyl greenhouse. We found that R. solani AG-1(IB) caused seedling rot of Kamchatka goatsbeard.

• Research in Plant Disease
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• v.28 no.1
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• pp.1-18
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• 2022

Volatiles exist ubiquitously in nature. Volatile compounds produced by plants and microorganisms confer inter-kingdom and intra-kingdom communications. Autoinducer signaling molecules from contact-based chemical communication, such as bacterial quorum sensing, are relayed through short distances. By contrast, biogenic volatiles derived from plant-microbe interactions generate long-distance (>20 cm) alarm signals for sensing harmful microorganisms. In this review, we discuss prior work on volatile compound-mediated diagnosis of plant diseases, and the use of volatile packaging and dispensing approaches for the biological control of fungi, bacteria, and viruses. In this regard, recent developments on technologies to analyze and detect microbial volatile compounds are introduced. Furthermore, we survey the chemical encapsulation, slow-release, and bio-nano techniques for volatile formulation and delivery that are expected to overcome limitations in the application of biogenic volatiles to modern agriculture. Collectively, technological advances in volatile compound detection, packaging, and delivery provide great potential for the implementation of ecologically-sound plant disease management strategies. We hope that this review will help farmers and young scientists understand the nature of microbial volatile compounds, and shift paradigms on disease diagnosis and management to aromatic (volatile-based) agriculture.

• Parasites, Hosts and Diseases
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• v.58 no.5
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• pp.559-564
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• 2020

A survey of rodents and chiggers associated with Orientia tsutsugamushi was conducted in a rural region of the Republic of Korea (Korea) between 2014 and 2018. Overall Apodemus agrarius 15.2% had the highest seropisitive for O. tsutsugamushi, followed by Myodes regulus 11.4%. Monthly risk factors using logistic regression analysis were not associated with O. tsutsugamushi infections in rodents. The overall prevalence rate of O. tsutsugamushi among chiggers was 0.3%. The chigger (Leptotrombidium scutellare) and monthly (October) risk factors were associated with O. tsutsugamushi human infections (P<0.05). Orientia tsutsugamushi infections are endemic in rodents in Korea and people, for example, soldiers who are active outdoors, must employ preventive measures, especially during October (P<0.05). When there are many reports of O. tsutsugamushi infections in Korea. The Boryong strain 85.7% (2/14) was the most common strain detected in chiggers, followed by the Shimokoshi 7.1% (1/14) and Karp 7.1% strains.

• Research in Plant Disease
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• v.11 no.2
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• pp.208-212
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• 2005

At the survey of June, 2002, total 294 dead frees were found in 20 ha of Black pine (Pinus thunbergii) forest located in the western coastal region of Korean peninsula. The dead trees were scattered over the 27 place as groups of about ten trees each. As a result of the field survey on the relationship between the conditions of dead trees and the occurrence of fruiting bodies of Rhizina undulata around the dead and/or dying trees, from June 2002 to August 2004 in the four plots, the occurrence of infected trees was observed as a shape of an irregular concentric circle from the first infected tree and R. undulata was found mainly around the dead tree. Because there was no observation of any other insects and pathogens which would kill trees, the cause of tree death in groups was considered owing to R. undulata. From the analysis of the physical and chemical proper ties of the soil collected from the damaged areas, the pH of soil was between 4.6 and 5.8 and the contents of soil nutrients were very low. Any "fire" trace was not found at all the 27 damaged places in the area, Taean, Chungcheongnam-Do, which are generally known as an important factor to initiate development of the disease. Therefore, further examination is needed to verify precisely about other environmental factors related with the group dying of the Black pines in this area beside 'fire'.

• The Plant Pathology Journal
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• v.39 no.4
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• pp.397-408
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• 2023

Fire blight disease, caused by Erwinia amylovora, is a devastating affliction in apple cultivation worldwide. Chemical pesticides have exhibited limited effectiveness in controlling the disease, and biological control options for treating fruit trees are limited. Therefore, a relatively large-scale survey is necessary to develop microbial agents for apple trees. Here we collected healthy apple trees from across the country to identify common and core bacterial taxa. We analyzed the endophytic bacterial communities in leaves and twigs and discovered that the twig bacterial communities were more conserved than those in the leaves, regardless of the origin of the sample. This finding indicates that specific endophytic taxa are consistently present in healthy apple trees and may be involved in vital functions such as disease prevention and growth. Furthermore, we compared the community metabolite pathway expression rates of these endophyte communities with those of E. amylovora infected apple trees and discovered that the endophyte communities in healthy apple trees not only had similar community structures but also similar metabolite pathway expression rates. Additionally, Pseudomonas and Methylobacterium-Methylorobrum were the dominant taxa in all healthy apple trees. Our findings provide valuable insights into the potential roles of endophytes in healthy apple trees and inform the development of strategies for enhancing apple growth and resilience. Moreover, the similarity in cluster structure and pathway analysis between healthy orchards was mutually reinforcing, demonstrating the power of microbiome analysis as a tool for identifying factors that contribute to plant health.