• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.46-51
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• 2015

BACKGROUND: This study aimed at investigating the effects of sulfur-containing compounds widely used as environment-friendly organic fungicides against ginseng anthracnose, and determining the appropriate application concentration for lowering chemical injury to ginseng leaves. Ginseng anthracnose, caused by Colletotrichum gloeosporioides, is a destructive disease that significantly reduces the yield of ginseng. METHODS AND RESULTS: Ginseng anthracnose, caused by Colletotrichum gloeosporioides, is a destructive disease that significantly reduces the yield of ginseng. In a 2-year-old ginseng grown in a pot, treatment with loess-sulfur complex containing 0.06% sulfur and fermented loess-sulfur complex containing 0.13% sulfur did not show any chemical injuries. In order to measure the therapeutic effectiveness, various sulfur-containing compounds were applied to the plants after they were infected with ginseng anthracnose. Treatment with lime sulfur complex (400 dilution) showed the highest ginseng anthracnose control value, followed by fermented loess-sulfur complex (20 dilution), fermented loess-sulfur complex (40 dilution), and loess-sulfur complex (400 dilution) treatments. These compounds were applied before the outbreak of anthracnose disease in order to measure the preventive effectiveness, and in this case, treatment with fermented loess-sulfur complex (40 dilution) showed the highest control value and it was comparable to the value of the pesticide treatment used as the control in this experiment. CONCLUSION: Fermented loess-sulfur complex could be recommended as an environment-friendly organic material to control the occurrence of ginseng anthracnose.

• Research in Plant Disease
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• v.24 no.4
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• pp.328-331
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• 2018

A severe disease with leaf spots and necrotic symptoms was observed in cucumber (Cucumis sativus L.) seedlings in April 2018 at a nursery in Kimjae, Korea (35o 47'09.8"N 127o 2'24.3"E). The infected plants initially showed spots on water-soaked cotyledons which, at later stages, enlarged and spread to the leaves, which the lesions becoming dry and chlorotic. The symptomatic samples were collected from cucumber and the isolates were cultured on LB agar. The representative bacterial strain selected for identification showed fluorescent on King's medium B, was potato rot-positive, levan and arginine dihydrolase-negative, oxidase-negative and tobacco hypersensitivity-positive in LOPAT group 2 as determined by LOPAT tests. A pathogenicity test was carried out on a 3-week-old cucumber. After 3 days of inoculation, leaf spots and necrotic symptoms appeared on the cucumber, similar to the originally infected plants. The infecting bacterial strain was identified as Pseudomonas viridiflava, by 16S rDNA sequence analysis. This is the first report of leaf spot diseases on cucumber caused by P. viridiflava.

• Korean Journal of Breeding Science
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• v.43 no.3
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• pp.184-189
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• 2011

'Younghan' (Hordeum vulgare L.), a winter barley for forage use, was developed by the breeding team at the Department of Rice and Winter Cereal Crop, National Institute of Crop Science, Rural Development Administration in 2008. It was derived from a cross between $F_1$['YB3433-3B-5'/'YB3135-3B-2-3'] and 'YB3135-3B-2-3'. 'SB971305-B-B-B-4-4' line was selected for its earliness, resistance to disease and good agronomic characteristics. The promising line showed both high yield and lodging resistance in the yield trials in Iksan in 2004 to 2005, and designated as 'Iksan420'. The line was subsequently evaluated for winter hardiness, earliness, and yield at eight locations throughout Korea for two years from 2007 to 2008 and finally named as 'Younghan'. It has the growth habit of IV, erect plant type, green leaf and thick culm in diameter. Its heading date was April 24, and the maturing date was May 25 in paddy field conditions, which were one day earlier than those of the check cultivar 'Youngyang'. The cultivar 'Younghan' had better winter hardiness, and resistance to lodging and BaYMV than those of the check cultivar did. The average forage dry matter yield of 'Younghan' was approximately 12.0 MT/ha in adapted region. 'Younghan' also showed 8.5% of crude protein content, 27.2% of ADF, and 67.1% of TDN, including higher grade of silage quality for whole crop barley. This cultivar would be suitable for (area with daily minimum temperature in January) above $-8^{\circ}C$ in Korean peninsula.

• Research in Plant Disease
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• v.18 no.4
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• pp.387-390
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• 2012

Rice black-streaked dwarf virus (RBSDV) was reported to occur on maize plants in Gochang-gun of Jeonllabuk-do region in 2011. The symptoms typically include stunted and deformed leaves. Virus infected plants usually produce poor or no head. RT-PCR analysis of genomic dsRNA extracted from the plant confirmed the infection. Specific primers for full length genome of segments 8 and 10 were used for RNA amplification. Full-length genomes of S8 and S10 were cloned and sequenced. Sequence analysis revealed that the S8 and S10 sequences of the maize isolate were same with rice isolate in size, 1,936 nt and 1,801 nt, respectively. In comparison with rice RBSDV, S8 and S10 showed 94.9-99.6% and 94.1-98.4% sequence identity, respectively. Phylogenetic analysis showed that RBSDV S8 and S10 of maize plants are categorized into the same group as RBSDV of rice plant.

• Research in Plant Disease
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• v.23 no.3
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• pp.256-261
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• 2017

The effects of insecticide and fungicide treatment were investigated to reduce mycotoxin contamination of corn (Zea mays L.) seeds. Deoxynivalenol and zearalenone contents were reduced in the treated seeds, but aflatoxin, ochratoxin A, fumonisin, and T-2 toxin were not effective by chemical treatments. The chemical treatment did not affect the growth of saprophyte, but inhibited the pathogenic fungi such as Fusarium verticillioides, F. graminearum and F. equiseti. Myotoxin contents at different harvesting time were compared. As the harvest time was delayed, both levels of deoxynivalenol and zearalenone and frequency of Fusarium spp. increased. However, the major nutrient contents of corn seeds were not affected by harvesting period. These results show that chemical treatments are necessary to reduce the fungal contamination of corn and harvest without delay is important as well.

• Research in Plant Disease
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• v.21 no.4
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• pp.315-320
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• 2015

Soybean mosaic virus (SMV) is a prevalent pathogen that causes significant yield reduction in soybean production worldwide. SMV belongs to potyvirus and causes typical symptoms such as mild mosaic, mosaic and necrosis. SMV is seed-borne and also transmitted by aphid. Eleven SMV strains, G1 to G7, G5H, G6H, G7H, and G7a were reported in soybean varieties in Korea. A reverse transcription loop-mediated isothermal amplification (RT-LAMP) method allowed one-step detection of gene amplification by simple procedure and needed only a simple incubator for isothermal template. This RT-LAMP method allowed direct detection of RNA from virus-infected plants without thermal cycling and gel electrophoresis. In this study, we designed RT-LAMP primers named SML-F3/B3/FIP/BIP from coat protein gene sequence of SMV. After the reaction of RT-LAMP, products were identified by electrophoresis and with the detective fluorescent dye, SYBR Green I under daylight and UV light. Optimal reaction condition was at $58^{\circ}C$ for 60 min and the primers of RT-LAMP showed the specificity for nine SMV strains tested in this study.

• Research in Plant Disease
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• v.14 no.3
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• pp.153-158
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• 2008

This study was conducted to develop a easy seedling method to test large amounts of barley and wheat cultivars for resistance of powdery mildew. In addition, we also examined the resistance of genetic resources that have been used in barley and wheat breeding programs in Korea. This seedling test used paper bag with seeds can be completed within three weeks. to-day seedlings were available to inoculation and 8 days was needed for result reading. This method can test at least 180 collections at one time. we can identify the two resistant types by leave symptoms showed non infection and necrotic spots. Among the 79 Korean barley cultivars, only two cultivar, 'Sangrokbori' and 'Dajinbori' were resistant and 'Jejubori' showed moderate resistant. There was no resistant in hulless barley and wheat cultivars. It was same results in comparison of earlier resistant reports in field test. We confirm that this method could using in test of powdery mildew resistance in barley and wheat. Among the 1,401 genetic resources using in Korean breeding program, malting barley has more resistant collections comparing to 796 hulled and hulless barley and 273 wheat germplasms.

• Research in Plant Disease
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• v.10 no.2
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• pp.87-93
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• 2004

Rhizome rot of ginger, caused by Pythium myriotylum, a major limiting factor for its production, has occurred annually, but become severe, especially in hot and humid years with frequent rainfalls in Korea. Most studies on rhizome rot have been carried out since 1980s in the National Institute of Agricultural Sciences and Technology, Honam Crop Experimental Station and Choongnam Provincial Rural Development Administration. Many aspects of rhizome rot, such as survey of the disease incidence, taxonomy, pathogenicity and physiology of pathogen, and ecology of soilborne inocula have been studied in the researches. However, intensive studies have been concentrated on management technologies of the disease including seed-rhizome disinfection, soil sterilization, evaluation of cultivar resistance, and fungicide application, and most developed technologies have been used in commercial farmings. In future, development of resistant varieties and simple soil disinfection technologies applicable in Korean condition and economically feasible fungicide application technology have to be developed for better management.

• Research in Plant Disease
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• v.25 no.2
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• pp.98-101
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• 2019

Pak choi (or a Bok choy; Brassica rapa subsp. chinensis) is a popular brassicaceous vegetable worldwide. In January 2019, a downy mildew symptom on pak choi was found at a farm located in Yongin, Korea. Based on morphological characteristics and molecular phylogenetic inference, the pathogenic oomycete was identified as Hyaloperonospora brassicae. To our knowledge, this is the first report of downy mildew disease occurring on pak choi in Korea. Considering the increasing demand for this crop, this pathogen would be a potentially new threat to the cultivation of pak choi in Korea.

• Research in Plant Disease
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• v.27 no.4
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• pp.187-191
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• 2021

Wilt symptoms were frequently observed in Korean blackberry (Rubus coreanus) plants grown in farmers' fields located in Gochang and Jeongeup, Jeonbuk Province, Korea during disease surveys in July 2020. The disease occurred in 10 of the 13 fields surveyed in the two locations. The incidence of diseased plants in the fields was 5-80%. Seven isolates of Fusarium sp. were obtained from the diseased plants and examined for their morphological and molecular characteristics. All the isolates belonged to Fusarium oxysporum species complex based on the morphological characteristics but were identified as F. cugenangense based on the molecular characteristics. Two isolates of F. cugenangense were tested for pathogenicity on Korean blackberry plants by artificial inoculation. Pathogenicity of the two isolates on the plants was confirmed with the inoculation tests, which showed wilt symptoms similar to those observed in the diseased plants in the fields investigated. This is the first report of F. cugenangense causing Fusarium wilt in Korean blackberry.