• The Plant Pathology Journal
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• 제19권6호
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• pp.294-300
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• 2003

Bacterial strains were isolated from diseased samples of shoot blight collected from different pear growing orchards of Chuncheon, Korea from 1995 to 1998. Forty-nine strains showed their pathogenicity on immature fruit and shoot of pear. Microbiological, physiological, and biochemical tests were performed on these pathogenic strains. One strain, designated as WT3 in this study, was selected as a representative strain as it was collected from the first outbreak area in Jichonri, Chuncheon in 1995. Further detailed characterization of the strain WT3 was done by PCR amplification using specific primers described previously for distinguishing Erwinia pyrifoliae from its close pathogen Erwinia amylovora. Based on phenotypical, biochemical, and molecular analyses, strain WT3 was identified as a shoot blight pathogen which was the same as E. pyrifoliae Ep16 previously described by a German group in 1999.

• The Plant Pathology Journal
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• 제28권2호
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• pp.172-184
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• 2012

An infection risk model for Phytophthora blight on chili pepper was developed to estimate the first date of disease occurrence in the field. The model consisted of three parts including estimation of zoosporangium formation, soil water content, and amount of active inoculum in soil. Daily weather data on air temperature, relative humidity and rainfall, and the soil texture data of local areas were used to estimate infection risk level that was quantified as the accumulated amount of active inoculum during the prior three days. Based on the analysis on 190 sets of weather and disease data, it was found that the threshold infection risk of 224 could be an appropriate criterion for determining the primary infection date. The 95% confidence interval for the difference between the estimated date of primary infection and the observed date of first disease occurrence was $8{\pm}3$ days. In the model validation tests, the observed dates of first disease occurrence were within the 95% confidence intervals of the estimated dates in the five out of six cases. The sensitivity analyses suggested that the model was more responsive to temperature and soil texture than relative humidity, rainfall, and transplanting date. The infection risk model could be implemented in practice to control Phytophthora blight in chili pepper fields.

• 한국농림기상학회지
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• 제3권1호
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• pp.16-21
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• 2001

1997~1998년에 무인기상관측장비(AWS)로부터 얻어진 기상자료와 고추 역병 발병과의 상관관계를 기초로 하여 고추역병 발병모형들을 작성하였다. 그 중에서 $R^2$값이 가장 높은 모형을 이용하여 AWS 시스템기상 파일을 입력받아서 발병률을 추정해주는 컴퓨터 시스템(PEPBLIGHT)을 구축하였다. 이 컴퓨터 시스템은 쉽게 무인기상관측장치로부터 기상 자료를 입력받을 수 있으며, 다른 기종의 무인기상관측장치와 다른 발병예측모형으로 이용할 경우에도 호환성이 있도록 하였다. 또한 AWS 미기상 자료를 SAS 입력자료로 사용하기에 적합한 형태로 변환해 파일로 저장해 주는 기능도 가지고 있다. 국내에서 처음으로 개발된 고추 역병 예찰 프로그램인 PEPBLIGHT는 MS사의 윈도운영체제로 운영되는 PC에서 사용할 수 있기 때문에 농가 수준에서도 이용할 수 있을 것이다.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.374-383
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• 2021

Rhizoctonia solani is one of the major pathogens that cause sheath blight disease in rice. Sheath blight is one of the most difficult diseases to control. Biological control (with the use of rhizobacteria) is one of the ways to control this disease. Plant Growth Promoting Rhizobacteria (PGPR) is a rhizosphere bacterium that can be used to enhance plant growth. The composition of the rhizobacteria in organic and nonorganic soil is affected by the chemical characteristics of the soil - which influences plant physiology and root exudation patterns. This study aimed to obtain a species of rhizobacteria which shows PGPR activity, from organic and nonorganic rice fields and test their capability to suppress R. solani growth. Out of 23 isolates screened for PGPR activity, the following isolates showed high PGPR activity and were selected for in vitro antagonistic activity testing against R. solani: ISO6, ISO11, ISO15, ISN2, ISN3, and ISN7, The six isolates produced 43,42-75,23 ppm of IAA, possessed phosphorus solubilization capability, and chitinase-producing activity. ISO6 (54.88%) and ISN7 (83.33%) displayed high inhibition capacities against R. solani, in vitro. ISO6 and ISN7 inhibited the growth of R. solani lesions on rice leaves by 89% and 100% (without lesion), respectively, after 7 days of incubation. Analysis of their 16S rRNA sequences revealed that the ISO6 isolate was Citrobacter freundii and ISN7 isolate was Pseudomonas aeruginosa.

• The Plant Pathology Journal
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• 제38권5호
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• pp.522-532
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• 2022

Gummy stem blight (GSB), a common and serious disease in cucurbits worldwide, is caused by three genetically distinct species: Stagonosporopsis cucurbitacearum (syn. Didymella bryoniae), S. citrulli, and S. caricae. In Korea, however, the three species of Stagonosporopsis have been barely characterized. In this study, 21 Stagonosporopsis isolates were recovered from watermelon (Citrullus lanatus) and muskmelon (Cucumis melo) leaves and stem showing blight symptoms collected from 43 fields in Korea. Sequence analysis performed with an internal transcribed spacer region was not competent to differentiate the Stagonosporopsis isolates. On the contrary, analysis of β-tubulin (TUB) genes and three microsatellite markers, Db01, Db05, and Db06, successfully differentiated Stagonosporopsis isolates. Further sequence analysis identified two Stagonosporopsis species, S. citrulli and S. caricae, and one previously unknown species of Stagonosporopsis. Representative isolates from three species caused dark water-soaked lesions on the detached watermelon and muskmelon leaves with no significant differences in the aggressiveness. Our results indicate that the S. citrulli, S. caricae, and unknown Stagonosporopsis sp. are all causal agents of GSB for both watermelon and muskmelon. This is the first report of a new species and the population structure of Stagonosporopsis species causing GSB in Korea.

• The Plant Pathology Journal
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• 제38권5호
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• pp.490-502
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• 2022

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) disease in rice (Oryza sativa L.) and it is among the most destructive pathogen responsible for severe yield losses. Potential bacterial biocontrol agents (BCAs) with plant growth promotion (PGP) abilities can be applied to better manage the BLB disease and increase crop yield, compared to current conventional practices. Thus, this study aimed to isolate, screen, and identify potential BCAs with PGP abilities. Isolation of the BCAs was performed from internal plant tissues and rhizosphere soil of healthy and Xoo-infected rice. A total of 18 bacterial strains were successfully screened for in vitro antagonistic ability against Xoo, siderophore production and PGP potentials. Among the bacterial strains, 3 endophytes, Bacillus sp. strain USML8, Bacillus sp. strain USML9, and Bacillus sp. strain USMR1 which were isolated from diseased plants harbored the BCA traits and significantly reduced leaf blight severity of rice. Simultaneously, the endophytic BCAs also possessed plant growth promoting traits and were able to enhance rice growth. Application of the selected endophytes (BCAs-PGP) at the early growth stage of rice exhibited potential in suppressing BLB disease and promoting rice growth.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.94.1-94
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• 2003

Control of bacterial blossom blight of kiwifruit (Actinidia deliciosa) has been mainly depended on chemical control. Recently cultural practices such as trunk girdling of kiwifruit trees and rainproof installation over kiwifruit trees also were conducted as the alternative control practices. Each of the control methods was evaluated for the best practicing conditions for the control of bacterial blossom blight of kiwifruit. Among the various combinations of spray times and spray periods, optimum spray program of antibiotics was turned out to be 3 times with intervals of 10 days from early May during the flowering season of kiwifruits. Optimum periods of trunk girdling of kiwifruit trees were from late March to late April. Trunk girdling with 20-30 mm wide showed best control efficacies on bacterial blossom blight, irrespective of the heights of girdling on trunks of kiwifruit trees. Optimum period of rainproof installation over kiwifruit trees was from March till late April, irrespective of installation methods.

• The Plant Pathology Journal
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• 제40권3호
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• pp.282-289
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• 2024

Fire blight is a bacterial disease caused by Erwinia amylovora. In Korea, fire blight was first reported in 2015 in an orchard. If the infection is confirmed, all trees in the orchard must be removed and the orchard must remain closed for 3 years. Since 2020, if the number of trees infected with fire blight is less than 5% of the total trees in the orchard, only the infected tree and adjacent trees are removed in Korea. Three years after removal, the trees can be replanted after confirming that the orchard soil is free from E. amylovora. In this study, a protocol was established for detecting E. amylovora in soil via selective enrichment, using tryptic soy broth with 0.05% bile salts and 50 ㎍/ml cycloheximide, and real-time polymerase chain reaction. This protocol resulted in a 1,000-times improved detection limit for E. amylovora in soil samples compared to that in unenriched samples. Soil monitoring was performed for orchards where fire blight-infected trees had been removed 3-27 months prior; the selected orchards were monitored every 3 months. Monitoring confirmed that E. amylovora was not present in the soil at any site in any of the orchards. A new detection protocol facilitates the monitoring of E. amylovora in soil and could help permit the replanting of trees in orchards. Also monitoring results provide evidence that trees can be planted earlier.

• Current Research on Agriculture and Life Sciences
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• 제18권
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• pp.9-17
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• 2000

풋마름병과 역병에 복합저항성인 계통을 육성하기 위한 노력으로서 앞서 역병 저항성으로 육성한 계통(16-2-3-2 = 역병 저항성 '칼미초', 19-1-3-7-1-1, 19-2-4-5-3-2 = 역병 저항성 '수비초', 김 등, 1996)과 풋마름병 저항성 계통(KC350 = MC 4, KC353 = PBC631)을 교배하여 육성한 $F_5$와 $BC_1F_4$, $F_6$와 $BC_1F_5$ 세대에 대해 1999년과 2000년에 각각 풋마름병과 역병에 대한 복합저항성을 검정하였다. 풋마름병과 역병에 복합 저항성을 보인 개체를 선발하여 다음 세대의 종자를 채종하였다.

• 식물병연구
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• 제17권3호
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• pp.402-404
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• 2011

2009년 9월 경기도 동두천시와 화성시 소재 농가에서 팔레놉시스 재배중 생육이 부진하고 하엽이 황화되며 심한 경우 뿌리와 기부가 마르고 식물체 전체가 말라죽는 증상이 발생하였다. 말라죽은 기부와 수태표면에 흰색 곰팡이 균사와 함께 둥근 형태의 적갈색 균핵이 관찰되었다. 균학적 특징으로 균사는 $25-30^{\circ}C$에서 가장 활발한 생장을 보였으며, 균핵은 갈색의 둥근형태로 직경은 1-3 mm 였다. 병원성 검정결과 병징이 접종 후 5일째 관찰되었으며 그 후 급속하게 진전되어 강한 병원력을 보였다. 팔레놉시스에서 발생한 병징과 병원균의 균학적 특징 및 병원성을 검정한 결과 이 증상은 Sclerotium rolfsii에 의한 흰비단병으로 동정되어 본 병을 팔레놉시스 흰비단병으로 명명하고자 한다.