• Research in Plant Disease
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• v.19 no.3
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• pp.216-219
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• 2013

A total of 75 soybean cultivars developed in Korea was screened against soybean cyst nematode (SCN), Heterodera glycines HG type 2.5. Cysts developed on soybean cultivars ranged from 104 to 624 cysts per pot. There was no resistant cultivar but 'Jangyeopkong', 'Saealkong', 'Miryangkong', and 'Mansukong' were moderately resistant; 33 cultivars were moderately susceptible and the other cultivars were susceptible. 'Jangyeopkong', 'Saealkong', 'Miryangkong', and 'Mansukong' could be recommended for soybean fields infested with SCN until developing SCN resistant soybean.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.630-635
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• 1998

Tobacco mosaic tobamovirus (TMV), cucumber mosaic cucumovirus (CMV), cucumber green mottle mosaic tobamovirus (CGMMV) and zucchini yellow mosaic potyvirus (ZYMV) from individual fruits and seeds of hot pepper and cucumber were detected by the reverse transcription-polymerase chain reaction (RT-PCR). The dilution end-points for RT-PCR in curde sap from TMV. and CMV - infected hot pepper leaves and CMV - and CGMMV-infected cucumber leaves were 10-5. However, the amount of PCR product obtained from preparation of ZYMV-infected cucumber leaf was 10-fold lower than those of CMV or CGMMV-infected cucumber leaves. In hot pepper, both TMV and CMV were detected in all parts of the fruit wall tissue, but the yields of PCR products in the fruit stalk and its surrounding tissues were higher than those of the end parts of the fruit. On the other hand, in cucumber fruit infected with CMV, CGMMV or ZYMV, the fruit wall tissue and seed located in both stalk and end parts showed higher yields of PCR products than those of intermediate parts. Of five viruses that were analysed, only TMV in hot pepper seed, and CGMMV and CMV in cucumber seed were detected in testa parts.

• Research in Plant Disease
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• v.11 no.2
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• pp.135-139
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• 2005

Bacterial canker of Japanese apricot (Prunus mume Sieb. et Zucc.) was found in all orchards located at southern area of Korea. Typical symptoms were characterized by dark spots formed on fruits, brown lesions on leaves, and bacterial exudate oozed out of the cracked bark of diseased tree. Thirty-eight isolates from 16 different areas were identified on the basis of biochemical and physiological characteristics (LOPAT and GATTa test) and also on the basis of 165 rDNA and ITS sequences. Pathogenicity tests confirmed that bacterial canker of Japanese apricot in Korea is caused by Pseudomonas syringae pv. morsprunorum.

• Research in Plant Disease
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• v.16 no.2
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• pp.121-124
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• 2010

Immunocapture reverse transcription polymerase chain reaction (IC-RT-PCR) was applied to the detection of Cucumber green mottle mosaic virus (CGMMV), Kyuri green mottle mosaic virus (KGMMV), and Zucchini green mottle mosaic virus (ZGMMV) on Cucurbitaceae crops. These seed-borne tobamoviruses were accurately detected from the infected leaves and seeds by IC-RT-PCR. This method was estimated to be about 100 times more sensitive than ELISA, and also it allowed the direct confirmation of ELISA results by using the captured antigens from a completed ELISA microwell. This convenient and reliable method could be used routinely for large-scale field surveys or seed tests of Cucurbitaceae crops.

• Research in Plant Disease
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• v.9 no.1
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• pp.36-38
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• 2003

Stem blight of brunfelsia (Brunfelsia calycina) caused by Fusarium oxysporum was found in greenhouse around Sungnam area, Kyunggi province, Korea in September 2001. The initial infection appeared as a slight wilting of the foliage, turned yellow from the lower leaves. The yellowing leaves were falled, resulting in blight of stem and eventual death of the entire plant. The vascular tissue of a diseased plants became dark brown and browning of the vascular system was a characteristic of the disease and the pith remained healthy, Isolates obtained from the lesions of the diseased plant were identified as F. oxysporum, based on the morphological characteristics of conidia. Symptom by artificial inoculation was same to the symptom of naturally infected plants. This is the first report demonstrating the stem blight on a brunfelsia caused by F. oxysporum in Korea, and we proposed to name this disease "stem blight of brunfelsia".

• Research in Plant Disease
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• v.14 no.1
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• pp.26-31
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• 2008

Anthracnose caused by Colletotrichum spp. has been known as a significant disease which commonly infects to the fruits of Chinese matrimony (Lycium chinese) in the field conditions. To select effective fungicides for the control of Chinese matrimony anthracnose, the antifungal activity of 15 fungicides were evaluated with 13 different strains of Colletotrichum spp. in the laboratory condition. Six fungicides (Dithianon WG, Tebuconazole SC, Tebuconazole WG, Trifloxystrobin + Tebuconazole SC, Azoxystrobin SC and Polyoxin D zinc salt + Carbendazim WP) out of them, showed effective suppression with the mycelium growth of pathogenic fungus, and were selected to test in vivo of the field condition. Five fungicides, Dithianon WG, Tebuconazole WG, Trifloxystrobin + Tebuconazole SC, Tebuconazole SC and Azoxystrobin SC, were significantly effective to protect anthracnose of Chinese matrimony, the variety "Chungyang Jerae".

• Proceedings of the KOR-BRONCHOESO Conference
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• 1979.05a
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• pp.3.2-3
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• 1979

Bone conduction loss is one of the most common complication in chronic otitis media, and is mostly high frequency loss. Of 233 tympanomastoidectomy ears, 187 ears were considered eligible for this study. A histopathological change was examined in the natural otitis media of guinea pigs. It is our intention to analyze the pattern of bone conduction loss in chronic otitis media, and to correlate this findings with clinical and pathological changes in human and animal otitis media. l) In unilateral cases, a significant difference in bone conduction threshold was observed between normal and diseased ears, and between each frequency with significant interaction between 2KHz and 4KHz (p 0.01). 2) Using one way analysis of variance, mean bone conduction was compared with the duration of disease. We observed a significant difference (p 0.05) between each group of duration, except between 11-15 and 15-20 years group. 3) A comparison of bone conduction between stapes loss group and intact stapes group revealed significant t ratio (p 0.01) at each frequency. The effect of stapes loss on each frequency was evaluated, using one way analysis of variance. there were significant difference(p 0.05) between 250Hz and 500Hz. and between 2KHz and 4KHz. 4) A comparison of bone conduction between round window obliteration and nonobliteration group revealed significant t ratio (p 0.01) at each frequency. Using one way analysis of variance. the effect of round window obliteration was evaluated in each frequency. We observed significant difference (p 0.05) between 250Hz and 500Hz. and between 2KHz and 4KHz. 5) A comparison of bone conduction between cholesteatoma and non -cholesteatoma group revealed significant t ratio (p 0.01) only in 2KHz and 4KHz. No significant differency was observed in mean bone conduction. 6) In a histopathological study of natural otitis media in guinea pig, we observed inflammatory infiltration of the round window membrane, serofibrinous precipitate in the scala tympani, and degeneration of the organ of Corti most significant near the basal turn. These changes would explain high tone bone conduction loss in the process of chronic otitis media.

• Research in Plant Disease
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• v.12 no.2
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• pp.91-98
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• 2006

A filtrate powder, designated as KNF2022, produced from culture broth of Acinetobacter sp. KTB3 was tested for their inhibitory effects on Pepper mild mottle virus (PMMoV) infection to Nicotiana glutinosa or N. tabacum cv. Xanthi nc. When 1/100 dilution with distilled water was treated to the plants and PMMoV was inoculated, the inhibition was estimated to be 94.3 and 95.6%, respectively. The same concentrations of KNF2022 inhibited infections of Pepper mottle virus (PepMoV) and Cucumber mosaic virus (CMV) on Chenopodium amaranticolor by 97.1 and 92.5%, respectively. Duration of inhibitory activity of the filtrate powder from Acinetobacter sp. culture broth against PMMoV infection on N. glutinosa was maintained for 2 days at 80% inhibition level, however, the inhibitory effect was diminished from 4 days after treatment to 50% levels. To evaluate inhibitory effects on systemic host plants of the antiviral agent, symptom developments of PMMoV, PepMoV and CMV on KNF2022-treated pepper plants were investigated. Delayed symptom developments until 10 days after inoculation (DAI) were observed for all the three viruses when the viruses were inoculated individually, and these delayed symptom development effects were maintained until 30 DAI in case of PepMoV. Moreover, PepMoV was not detected by RT-PCR and ELISA until 30 DAI. These delayed symptom development effects were diminished in all combinations of three virus co-inoculations due to synergism of three viruses on symptom developments. Inhibitory effect of KNF2022 was verified under electron microscopic examinations using purified virus preparations. Particles of PMMoV and PepMoV were observed on specimens from 5 min after KNF2022 treatment, and the particle sizes were reached in the range of 200-250 nm and 400-600 nm, respectively. Furthermore, the viral particles were destructed and particle sizes were reached in the range of 100-150 nm and 300-500 nm, respectively, on 60 min after treatments. Reduction of local lesion numbers on N. tabacum cv. Xanthi nc and C. amaranticolor were accompanied with reduction of virus particle sizes. In the case of CMV destructed particle numbers were also increased according to incubation period after KNF2022 treatment and local lesions on C. amaranticolor were reduced.

• Research in Plant Disease
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• v.20 no.1
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• pp.37-49
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• 2014

A total of 2,714 methanol extracts of 1,677 plant species in 178 families were screened for nemastatic activity against Rhabditis sp. by 96-well microplate bioassay. The plant extracts with a concentration of $5,000{\mu}g/ml$ were mixed with aqueous nematode solution containing about 20 Rhabditis sp. and their activity was examined daily for 7 days. Out of 2,714 plant extracts examined in this test, 2,362 (87.0%) showed no negative influence on the nematode activity, while 187 (6.9%) inhibited nematode activity about 50%, 95 (3.5%) inhibited nematode activity over 90%, and 70 (2.6%) rather enhanced nematode activity. Among those showing over 50% nemastatic activity, 25 extracts were randomly selected for further screening with Rhabditis sp. and with juveniles of Meloidogyne incognita. The screening revealed that 11 extracts (44%) were consistently nemastatic. The 282 extracts with nemastatic activity could be of use in future studies on nematicidal plants.

• Research in Plant Disease
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• v.18 no.4
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• pp.338-348
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• 2012

Potato late blight caused by Phytophthora infestans Cooke is one of the major diseases in the cultivation of potatoes in Korea. Effect of chitosan preparations (SH-1 and SH-2) was evaluated on the inhibition of mycelial growth of P. infestans, and protective activity using detached potato leaf assay both in vivo and in the field test. SH-1 and SH-2 were showed protective activity of young plant with control values more than 95% potato late blight by inoculation with pathogens under growth chamber conditions. Mycelial growth was inhibited the radial growth over 74% at a concentration of $300{\mu}g/ml$ of both SH-1 and SH-2. Spraying with SH-1 and SH-2 on the leaves for detached leaf assay reduced disease development. The content of total polyphenol in stem was significantly increased by SH-1 and SH-2 application in the field. In field experiments, foliar application with both SH-1 and SH-2 were significantly reduced the development of late blight on potato plants. Control of late blight disease was obtained with control values of 72% and 53% by application of 1% SH-1 and SH-2, respectively, with 4 times at 7 days interval, and reduced with similar disease control values by application with 3 times at 14 days interval compared with untreated control. SH-1 and SH-2 applications increased the fresh weight of potato, and higher grade potatoes were also increased. The results showed that SH-1 and SH-2 applications can be used as eco-friendly natural fungicide for organic farming for the increase of yields and control of late blight.