• Research in Plant Disease
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• v.11 no.2
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• pp.213-216
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• 2005

Tomato spotted wilt virus (TSWV) occurred abruptly with a high incidence rate in 14 vegetable crops in Anyang area, Gyunggido in 2004. TSWV was identified by the symptoms on the indicator plants, immunocaptured reverse transcription-polymerase chain reaction (IC/RT-PCR), virion captured (VC)RT-PCR and RT-PCR using total RNA from the infected plants. Vegetable crops infected with TSWV included table tomato, cherry tomato, red pepper, lettuce, chicory, red leaf chicory, red mustard, dragon tongue, treviso, potato, perilla, sesame, pumpkin, and ssamchoo (hybrid of oriental cabbage and cabbage). The incidence of TSWV in fields ranged from 30 to $100\%$. TSWV usually produced necrosis, wilt and/or severe mosaic with typical single or double ring spots on the leaves. TSWV could be detected in Frankliniella occidentalis collected from the crops in the fields with $90\%$ rate by IC/RT-PCR.

• Korean journal of applied entomology
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• v.23 no.1 s.58
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• pp.22-27
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• 1984

The effects of solarization on the suppression of soilborne plant pathogen and the growth promotion of cucumber plants were examined in artificially infested soil by vinyl mulching and not mulching from July 25 to August 25, 1983. During the solarization period, the highest temperatures were $58^{\circ}C,\;45^{\circ}C,\;and\;42^{\circ}C$, at 5cm, 15cm, and 25cm of soil depth respectively. The inoculum of cucumber wilt pathogen, Fusarium oxysporum f. sp. cucumerinum, was mixed with soil 30cm deep and saturated with water. The pathogen was completely killed after 30dys of solarization in 5cm soil depth and 98 percent of inoculum was eliminated in 15cm soil depth. But the survival rate of the fungi in 25cm soil depth of solarized plot did not show significant differences compared with those in nontreated plot in 5cm and 15cm depth. Although some of the pathogenic fungi might survive from solarized soil in 15cm and 25cm depth, the ability of microconidia production was reduced significantly The number of microconidia grown on Komada's medium in isolates the primary colonies from solarized soil was less than that in isolates from nontreated soil approximately by one fourth. The first subcultured solates from the solarized soil grown on potato dextrose agar also produced a small amount of microc. onidia compare with that of subcultured isolates from nontreated soil. Cucumber seedlings planted in the soil collected from solarized plot grew much better than that in the soil from nontreated plot at any of soil loved, especially in 5cm of soil depth. And the fruits harvested from cucumber plants grown in the solarized plot were more in number and leavier in weight than that from nontreated plot. Besides the typical symptom development, significant growth suppression wvas recognized with increase of inoculum density of F. oxysporum f. sp. cucumerinum at early stage of cucumber seedlings in steam sterilized soil.

• Korean journal of applied entomology
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• v.25 no.3 s.68
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• pp.169-173
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• 1986

Ginseng fields abolished by potato rot nematode (Ditylenchus destructor) (heavily infested with the nematode) were treated with selected nematicides after preplanting treatment with fumigants or non fumigant chemicals in the fall of 1982. Suppression of the nematode populations was noted in the fields fumigated by cylon (Cy) and treated with ethoprop (E) or triazophos (T). Also in these treatments, high percentages of shoot sprouting and low nematode damages were observed. In the fields fumigated by Cy, subsequent treatments with nonfumigant nematicides such as E, aldicarb (A), phenamiphos (Ph), oxamyl (O) and carbofuran (C) during cultivation had no effect on the significant decrease of the nematode, compared with Cy alone. No differences in shoot sprouting and symptom appearance were observed; however, survivalities of plants and root weights of 4-year old ginseng were high in A and E or E following preplanting treatment with E. Correlation coefficients of the nematode densities to host responses such as sprouting of shoots, symptom appearance, survivality of plants and weight of 4-year old ginseng roots were significant at and mostly before and after the time periods of survey.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.976-982
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• 2005

Abilities of various edible plants and natural antioxidants to protect brain against oxidative damages were evaluated using brain homogenate of perfused Sprague-Dawley rat. Oxidative damage, expressed as lipid peroxidation (LPO), indicating total quantity of malondialdehyde and 4-hydroxyalkenal, increased from 4.1 to 6.9nmol/mg protein by treatment of $2.5{\mu}M$ ferrous sulfate and 7.5mM hydrogen peroxide as source of reactive oxygen species (ROS) on brain homogenate for 10min at $37^{\circ}C$ Mallow(88%) in leafy vegetables, small potato (93%) in root vegetables, green red pepper (76%) in fruit vegetables, and avocado (96%) in fruits showed highest LPO inhibition capacities. Ability of mushrooms decreased in order of nameko, shiitake, pine mushroom, oyster mushroom, and new type pine mushroom. Among natural antioxidants tested, (+)catechin (91%), (-)epigallocatechin gallate (85%), (-)epicatechin gallate (83%), and kaempferol(83%) showed high LPO inhibition capacities.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.652-655
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• 2013

Natural habitats of weedy melons were distributed on the islands along and on the west and south coasts of Korean peninsula including Boryeong, Seosan (Taean), Seocheon, Okgu, Buan, Gochang, Yeonggwang, Muan, Shinan, Haenam, Jindo, Wando, Goheung, Yeocheon, Hadong, Namhae, Goseong, Tongyeong, Geoje, and Jeju islands including Jeju city, Bukjeju-gun and Nam Jeju-gun. Weedy melons were found growing wildly in or around the cultivated lands in these regions. Natural habitats of weedy melons were in and around the cultivated lands. Weedy melon plants were found most often in soybean fields, followed by fields of mungbean, sweet potato, pepper, sesame, cotton, and peanuts. The plants were also found growing wild in foxtail millet fields, rice paddy levees along the streams, upland field edges, watermelon fields, corn fields, vegetable gardens near farmhouse, orange fields, compost piles, fallow fields, roadside and home gardens. They inhabited in sunny and a little dry spaces in relatively low-height crop plant fields in general. The time of fruit maturity was from early July to late October with the most frequency in September according to post survey answer. Fruits dropped off from the fruit stalk when matured. This phenomenon was thought beneficial for perpetuation in the wild. The fruits were being used commonly for food and toys for children. It was thought that weedy melons were perpetuating through the cycle of human and animal feeding of the fruits, human and animal droppings, often mixed in compost, and application of the compost to crop fields by human.

• Journal of Climate Change Research
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• v.8 no.4
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• pp.305-312
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• 2017

We aimed at investigating the difference in $N_2O$ emission factors of chemical and organic fertilizers and identifying the main factors influencing annual fluctuations in $N_2O$ emission. We conducted two-year experiments in 2016 and 2017 in an agricultural field planted with sweet potato (Ipomoea batatas). Treatments included chemical NPK fertilizer (NPK) and chicken compost application at $10\;ton\;ha^{-1}$, $20\;ton\;ha^{-1}$, and $30\;ton\;ha^{-1}$ rates (CK1, CK2 and CK3). Control was also employed with no addition. Results showed that $N_2O$ emission rates were significantly related with soil water status and soil available N contents. Significant correlation between % water filled pore space (WFPS) and $N_2O$ emission was observed only when the %WFPS was greater than 40% and during the initial stage of the experiment (<60 d). Comparison of the emission factors in 2016 and 2017 showed us that the emission factor was greater in 2016 when the %WFPS was maintained higher by 16.5% compared to that in 2017. In 2016, the emission factor of organic fertilizer was higher than that of chemical fertilizer, while in 2017, the pattern was reversed. Annual variability in $N_2O$ emission could also be originated from the available N contents remaining in soil after being taken up by plants. If we apply excessive N fertilizer, the soil would contain excess amount of N which was not uptaken by plants, leading to a huge increase in $N_2O$ emission. This case would overestimate emission factor, which was the case for the organic fertilizer in 2016. Over-fertilization should be avoided when we set up an experiment to determine $N_2O$ emission factor.

• 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.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.376-382
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• 2014

This work was conducted to investigate the variation of growth and yield among three generations ($TC_0$, $TC_1$, and $TC_2$) in the field cultivation of virus-free sweetpotato (Ipomoea batatas) plants. Virus-free generations of three cultivars ('Matnami', 'Shinhwangmi', and 'Yeonhwangmi') were cultivated with $75{\times}25cm$ planting density on May 20th, covered with black vinyl film. At 30 days after planting, vine growth in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, and vine length in $TC_0$ showed the highest growth among treatments. At harvesting time after 120 days, vine diameter, number of node, and number of branch in $TC_0$, $TC_1$, and $TC_2$ were more increased than farmer's plant, but were not statistically significant. Fresh weight of shoot in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant, but was not statistically significant among generations or cultivars. Number of tuber per plant and mean weight of tuber in $TC_0$ and $TC_1$ showed significant increasement, but that in $TC_2$ did not show significant difference as compared to the farmer's plant. Weight of tuber per plant in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. Marketable yield, percentage of marketable tuber, and percentage of small tuber (40 to 200g) in $TC_0$, $TC_1$, and $TC_2$ was significantly increased as compared to the farmer's plant. The large tuber over 300g showed the lowest percentage in $TC_0$. Marketable yield in $TC_2$ was significantly decreased as compared to $TC_0$, and was not significantly different as compared to the farmer's plant. Marketable yield in 'Matnami' was highest among cultivars. From this results, Farmers are required to renew every three years to maintain the yield and quality of virus-free plants. However, the exchange period of virus-free plants is desirable to renew every 2 or 3 years according to the degree of virus reinfection.

• Research in Plant Disease
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• v.20 no.1
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• pp.50-53
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• 2014

Rhizopus soft rot of lily (Lilium longiflorum) caused by Rhizopus oryzae was observed in the experimental field in Taean Lily Experiment Station in Korea, 2012. The typical symptoms were water-soaked lesions on bottom stem and leaf rot. The lesion rapidly expanded and the plant was softened totally. The fungus grew vigorously at an optimum temperature ($25^{\circ}C$) and brownish colony and black sporangia were formed on potato dextrose agar medium. Sporangiophores formed on end of sporangia were sub-globose, brownish and $6-10{\mu}m$ in size. Sporangia were globose, blackish and $87-116{\mu}m$ in size. Sporangiospores were irregularly oval and sub-globose, brownish $4-8{\mu}m$ in size. On the basis of mycological characteristics, analyzing sequences of internal transcribed spacer region of ribosomal DNA, and pathogenicity test on host plants, the causal fungus was identified as R. oryzae. This is the first report of Rhizopus soft rot on lily caused by R. oryzae in Korea.

• Research in Plant Disease
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• v.9 no.2
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• pp.89-93
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• 2003

An isolate of Tobacco mosaic virus (TMV) was isolated from potato cultivar ‘Chubak’ showing vein clearing and mild mosaic at Namhae in Korea. This isolate, TMV-St, was differentiated from other tobamoviruses based on biological properties, serological relationships and nucleotide sequence analyses of coat protein genes. TMV-St caused typical symptoms on four indicator plants as compared to the tobamovirus of TMV-U1, Pepper mild mottle virus (PMMoV), and Tomato mosaic virus (ToMV), which caused economic losses in Solanaceous vegetables, tomato, pepper, and eggplant. Remarkably, the TMV-St induced distinctly different symptom of systemic chlorotic spots on Chenophodium murale. On C. murale, Gomphorena globosa, and Nic-otiana rustica, the four viruses were classed by the virulence of systemic or local infections. In serological test TMV-St antiserum showed a precipitation line with each other tabamovirus. The CP gene of TMV-St contain 477 nucleotides, and the nucleotides sequence was the most similar to that of TMV-U1.