• Research in Plant Disease
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• v.24 no.4
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• pp.302-307
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• 2018

From 2014 to 2016, approximately 5% of okra fruit were observed displaying gray mold symptoms at the research field of Jeollabuk-do Agricultural Research and Extension Services, Korea. The symptoms observed were water-soaked, brown or gray spots, and abundant mycelial with conidia appearing on the infected fruit. Initial infection commenced from the base of fruit and gradually moved to the pod, where it finally resulted in collapse. Colonies on potato dextrose agar were gray to grayish brown, felted and cottony expanding 65-80 mm after one week. The fungus formed several black sclerotia ranging $1.0-3.5{\times}0.5-3.0mm$ on the Petri dish after two weeks. The conidia were one-celled, ellipsoidal or ovoid, colorless or pale brown, and $6.2-15.4{\times}5.0-10.4{\mu}m$. Conidiophores arose solitary or in groups, straight or flexuous, septate, with an inflated basal cell brown to light brown, and measured $85-450{\times}10.0-40.0{\mu}m$. On the basis of the morphological characteristics and phylogenetic analyses of internal transcribed spacer rDNA, the fungus was identified as Botrytis cinerea Pers. Pathogenicity of a representative isolate was proved by artificial inoculation, fulfilling Koch's postulates. To our knowledge, this is the first report on the occurrence of B. cinerea on okra in Korea.

• Research in Plant Disease
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• v.6 no.1
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• pp.27-33
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• 2000

Population density of Plasmodiophora brassicae in soil of severely infested fields of Chinese cabbage decreased as soil depth increases. More than 97% of total population was found in surface soil (0-5cm depth), and a few resting spores of the pathogen were also detected in 40 cm-deep soil. the clubroot pathogen was evenly distributed over the surface soil without clustering around a Chinese cabbage plant. Density of P. brassicae in soil at 23 Chinese cabbage fields in Pyongchang, Kangwon province ranged widely from less than 10$^4$resting spores/g soil to above 10$\^$6/ resting spores/g soil. Few or none of P. brassicae was found in virgin soil without any cropping history, intermediate with 0.36-2.75$\times$10$^4$resting spores/g soil in fields of other crops but more than 10 times higher population was found in severely infected Chinese cabbage fields. Density of P. brassicae was highest in the fields of monocropping of crucifers with some exceptions, but was low in rotated fields with corn, rye, medicinal crops or other non-host vegetables. Pathoen density in soil was decreased rapidly when rye or medicinal crops were cultivated after Chinese cabbage, suggesting that survival of clubroot pathogen appears to be influenced greatly by cropping system. The improved method for detecting resting spores of P. brassicae in soil used in this study seemed to be adequate for estimating population density of P. brassicae in soil in aspects of clearer dyeing, increased detecting sensitivity, and simplicity in preparation.

• Research in Plant Disease
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• v.17 no.1
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• pp.1-12
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• 2011

Incidence of Phytophthora blight of hot pepper (Capsicum annuum) and yield (fresh weight) of pepper fruits were investigated at four separate fields located in Cheongwon, Boeun, Eumsung, and Goesan, which are major pepper production areas in Chungcheongbuk-Do. In all of the experimental fields except the Goesan field, increased incidence of Phytophthora blight led to decreased yield of pepper fruits. The harvest time in which the yield of red pepper fruits was highly correlated with the incidence of Phytophthora blight was different between areas: it was highly correlated in the third harvest in Cheongwon (y=-11.0x+435.2, $r^2$=0.99), but in the second harvest in Boeun (y=-15.0x+944.6, $r^2$=0.76). In contrast, there was a very low correlation between the pepper yield and the disease incidence in Goesan in which pepper seedlings grafted on resistant stocks were planted. The final disease incidence in the Cheongwon experimental field reached 100% more than 40 days later in 2007 compared with that in 2006. The control threshold of Phytophthora blight in the pepper fields where disease incidence had been lower than 5% was set as 0.8% disease incidence, which caused less than 5% yield loss.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.345-355
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• 2017

This study was conducted to evaluate rice seed disinfection efficacy of loess-sulfur for the suppression of Bakanae disease caused by Fusarium fujikuroi. Rice seeds were treated at different concentrations of loess-sulfur, soaking time and temperature, and combination of hot-water treatment. Rice cultivar, Shindongjin harvested from Bakanae disease-infested area in 2015, was used. Loess-sulfur was treated as follows; concentration of undiluted solution, 2%, 1% and 0.5%; soaking time of 24 and 48 hours; treatment temperature of $20^{\circ}C$ and $30^{\circ}C$; hot water treatment or not. Optimal conditions of rice seed disinfection were selected soaking time of 48 hours and the suspension of 0.5% and 1% loess-sulfur by investigating seed germination and isolation frequency of Fusarium spp. on Komada agar medium in vitro, and were established 3 disinfection conditions as hot water ($60^{\circ}C$, 10 min.) + 1% loess-sulfur ($20^{\circ}C$, 48 hours), 1% loess-sulfur only ($30^{\circ}C$, 48 hours) and 1% loess-sulfur only ($20^{\circ}C$, 48 hours) through additional test in greenhouse. Above 3 conditions were verified by rice seedling box and paddy field test in the way of investigating Bakanae diseased plants (%) and healthy plants (%). Consequently, most effective rice seed disinfection conditions on Bakanae disease were combination of hot water and 1% loess-sulfur and loess-sulfur only at $30^{\circ}C$. Furthermore, treatments with these conditions showed control value of 100% were maintained from seedling to the heading stage in the field. However, treatment of 1% loess-sulfur only at $20^{\circ}C$ showed low control value of 78.2% in paddy field. Hot water only treatment turned out to be an effective disinfection method when conducted thoroughly with $60^{\circ}C$, 10 min. However, it was thought additional soaking process with loess-sulfur after hot water treatment served more high control effect against Bakanae disease when rice seeds were disinfected on a large scale. This results expected rice seed disinfection with loess-sulfur were effectively and easily usable method if farmers had only one of either hot water-disinfector or seed-disinfector. In addition, loess-sulfur is well-known to farmers, simple to manufacture method and cheap.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.313-319
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• 2006

Two hundred bacterial strains were isolated from the soil around healthy tomato plants in a polyvinyl house, where most of the other plants showed bacterial wilt symptoms. The strains were screened in vitro for their antibacterial activity. Among them, a strain, KPB3 showed strong bactericidal activity against bacterial wilt pathogen, Ralstonia solanacearum. The strain KPB3 was identified using physiological and biochemical tests, and 16S rRNA analyses. Based on these tests, the strain was found to be closer to genus Paenibacillus. To control the bacterial wilt caused by R. solanacearum, greenhouse experiments were conducted to determine the effectiveness of the Paenibacillus strain KPB3. Drench application of this strain ($4{\times}10^8$ CFU $mL^{-1}$) into the pots containing tomato plants, post-inoculated with the pathogen, R. solanacearum could drastically reduce the disease severity, compared to the non-treated plants. To evaluate effectiveness of this strain under field conditions, experiments were carried out in polyvinyl houses infested with R. solanacearum, during spring and autumn of the year 2006. It was observed that, during spring, bacterial wilt was more prevalent compared to the autumn. During spring, 50.9% disease incidences occurred in non-treated controls, while, Paenibacillus strain KPB3 treated plants showed 24.6% disease incidences. Similarly, during autumn, around 17.2% plants were infected with bacterial wilt in non- treated polyvinyl houses, compared to the Paenibacillus strain KPB3 treated plants, which showed 7.0% disease incidences. These results demonstrated that, Paenibacillus strain KPB3 is a potential biological control agent against bacterial wilt caused by R. solanacearum, effective under greenhouse as well as field conditions. This is the first report showing biocontrol of R. solanacearum using a Paenibacillus spp. under field conditions.

• Korean Journal Plant Pathology
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• v.12 no.2
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• pp.214-218
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• 1996

배나무잎 이상반점증상의 보독여부를 신속정확하게 검정할 수 있는 목본 지표식물을 선발하기 위해 시험을 수행하였다. 신고x조생적 등 5개 교배조합 102개체를 공시해서 1차로 10개체를 선발하였다. 1차로 선발된 개체중에서 전형적인 이상반점증상이 조기에 잘 나타나고 이상반점증상과 유사한 검은무늬병에 저항성인 신고$\times$조생적 86-2-2 계통을 최종선발하였다. 선발된 지표식물을 사용하여 농가포장에서 이상반점 증상의 보독여부를 실증시험한 결과 보독유무의 조기판별이 가능하였다. 이상의 결과에서 최종 선발된 신고$\times$조생적 86-2-2계통을 PS-95로 명명하고자 한다.

• Korean journal of applied entomology
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• v.19 no.4 s.45
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• pp.240-242
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• 1980

Recently, a powdery mildew on the leaves of Capsium spp., Pimento and pepper, occurred greatly in the vinyl-house at Seungchon area, Chonnam province. According to the field survey, the disease is severe at high temperature and high humidity conditions in the vinyl house. Diseased loaves were severely fallen and remained only several top leaves, thus the setting and thickening of fruits were greatly depressed. The pathogenic fungus was identified as Oidiopsis taurica(Lev.) Arn., imperfect stage of Leveillula taurica (Lev.) Arn., The perfect stage of fungus was not observed. Optimum temperatures for conidial germination ranged at $25-30^{\circ}C$ with high humidity.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.307-308
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• 2000

어류에 축적된 유기화합물은 생식소와 생식세포에 직접적인 작용으로 수정을 저해(Spies et al., 1988)하고 부화율(Hose et al., 1982)을 감소시킬 수 있다. Bishenol A(BPA)는 음식용기와 음료 포장재료로 사용되고 있으며, 캔 용기, 병 뚜껑 그리고 물 공급용 파이프 등에 금속을 코팅하는 물질이다. 이 연구는, 내분비장애물질이 생물의 번식력과 종 연속성에 미치는 영향을 규명하는 연구의 일환으로, 송사리, Oryzias latipes의 수정란을 BPA에 침적처리 하였을 때 수정난의 초기발생에 미치는 영향과 송사리 어미에 BPA를 경구투여 하였을 때 산란량과 부화율에 미치는 영향을 번식생물학적 측면에서 탐색하였다 (중략)

• Proceedings of the Korean Society of Crop Science Conference
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• 2020.06a
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• pp.130-130
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• 2020

• The Korean Journal of Mycology
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• v.47 no.4
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• pp.393-406
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• 2019

In August 2017, anthracnose symptoms were observed on the petioles and leaf veins of Korean radish (Rhaphanus sativus) in Hongcheon, Jeongseon, and Pyeongchang of the Gangwon province, Korea. Many grayish to dark-brown spots of 1-2 mm in diameter, appeared on the lower surface and leaf veins of the radish leaves. The spots gradually enlarged and coalesced to form dark-brown irregular lesions. Ten Colletotrichum isolates were obtained from the affected tissues of the Korean radish. Out of them, eight isolates were identified as C. higginsianum and two isolates were identified as C. truncatum based on morphological characteristics and multi-locus molecular phylogenetic analysis using the internal transcribed spacers and intervening 5.8S rDNA (ITS), partial beta-tubulin gene (TUB2), partial actin gene (ACT), and partial chitin synthase-1 gene (CHS1). The pathogenicity test was carried out on wounded and unwounded Korean radish (cv. Siraegimu and Osarimu), and Chinese cabbage (cv. Chuno and Smart) by inoculating with a spore suspension. All isolates except one C. truncatum isolate developed typical symptoms on both wounded and unwounded Korean radish. In Chinese cabbage, only the plants inoculated with C. higginsianum isolates developed symptoms regardless of the wound. This is the first report of anthracnose caused by C. truncatum on Korean radish in Korea.