• Korean journal of applied entomology
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• v.17 no.2 s.35
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• pp.81-87
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• 1978

Late blight incited by Phytophthora infestans (Mont.) de Bary, is an important problem for seed potato prodcution in Korea. At the alpine Daekwanryeong area, unprotected potatoes are often defoliated within 14 days after late blight is first observed in the field. Since regular spraying can control late blight, the forecasting service is needed for timely initiation of the spraying program. Climatological data and notes on late blight incidence were recorded during 1970-1977 at the Alpine Experiment Station. The moving graph method using 7-day average mean temperature and 7-day total rainfall did not give highly accurate forecasts. Adding data on relative humidity and 7-day average minimum temperature increased the usefulness of the moving graph. Yields of late blight susceptible varietieties in sprayed plots were related to late blight occurrence and to the rainfall distribution pattern.

• Research in Plant Disease
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• v.9 no.4
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• pp.221-223
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• 2003

In May 2002, a destructive stem rot of Obedient plant (Physostegia virginiana) occurred sporadically in an exhibition farm of Hamyang-gun, Gyeongsangnam-do Agricultural Research and Extension Services, Korea. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted. White mycelial mats were spread over lesions and the sclerotia were formed on the stems near soil line. The sclerotia was globoid or irregular in shape, 1${\sim}$3 mm in size, and brown in color. The optimum temperature for fungal growth was about $30^{\circ}C$. The typical clamp connections were observed in the hyphae of the fungus grown on PDA, and hyphal diameter was 3.6${\sim}$9.4 ${\mu}m$. On the basis of mycological characteristics and test of pathogenecity to host plants, the fungus was identified as Sclerotium rolfsii. This is the first report on the stem rot of Physostegia virginiana caused by Sclerotium rolfsii in Korea.

• Research in Plant Disease
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• v.22 no.1
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• pp.55-58
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• 2016

A Cucumber mosaic virus (named CMV-Tr1) isolated from the white clover (Trifolium repens) showing mosaic and malformation that found in a pepper field. Cucumber mosaic virus was identified through confirmation with PT-PCR, PCR-restriction fragment length polymorphism, and sequence analysis of coat protein (CP) gene. CMV-Tr1 mosaic symptom on the upper leaves of five tobacco species including Nicotiana benthamiana, Cucumis sativus, Physalis angulata, and Solanum lycopersicon. In Chenopodium quinoa and Vigna unguiculata the isolate showed local lesions in inoculated leaves. CMV-Tr1 compared with CMV-As in the sequence identity of CP gene. CMV-Tr1 showed 98.9% and 99.5% homologies at nucleotide and amino acid levels, respectively. Phylogenetic analysis of the CP gene indicated that CMV-Tr1 belongs to the CMV subgroup IB base on the CP. To our knowledge, this is the first report of CMV in T. repens in Korea.

• Research in Plant Disease
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• v.10 no.1
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• pp.21-24
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• 2004

A destructive stem rot of pepper (Capsicum annuum) was found from the often field sporadically in Jingyemyon, Hadong-gun in July 2002 and vinyl houses in Moonsan-eup, Jinju City in October 2003. The same fungus also caused collar and crown rot and systemic wilt or blight of whole plant. White mycelium spread over stems of infected plants and sclerotia formed on the old lesions and near the soil surface. The fungus showed maximum mycelial growth around 3$0^{\circ}C$. The mycelial color is white and width of hyphae ranges 3.6∼10.2 ${\mu}{\textrm}{m}$, and formed clamp connection. Numerous sclerotia were farmed in artificial media such as PDA at 3$0^{\circ}C$. The shape of sclerotia were sphere and 1.0∼2.1 mm in diameter, The fungus was isolated repeatedly from the infected tissues and the pathogenecity of fungus to pepper (Capsicum annuum) was confirmed, and identified as Sclerotium rolfsii. This is the first report on the stem rot of pepper (Capsicum annuum) caused by Sclerotium rolfsii in Korea.

• Research in Plant Disease
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• v.8 no.4
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• pp.215-219
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• 2002

Fruit rot of pomegranate (Punica granatum) caused by Coniella granati were observed in several farmer's fields in Gwangdo-myon, Tongyeong City, Gyeongnam Province, Korea. The symptoms occurred on fruit with rotting then eventually dropping and mummification. The colony color of causal fungus was whitish on potato dextrose agar. Conidia were single celled, pale brown or olive in color at maturity, straight or slightly curved fusiform in shape, and were 10.3~17.4$\times$2.8~4.0 ${\mu}{\textrm}{m}$ in size. Conidiogenous cell were hyaline, branched only at the base aseptate, elongate, phialidic, enteroblastic and 12.4~1.4$\times$2.8~3.6 ${\mu}{\textrm}{m}$ in size. Pycnidia were black in color and globose in shape and 124.6~228.4 ${\mu}{\textrm}{m}$ in size. Optimum temperature for mycelial growth was $25^{\circ}C$. On the basis of mycological characteristics and pathogenecity test on host plants, the fungus was identified as Coniella granati. This is the first report on the fruit rot of pomegranate caused by Coniella granati in Korea.

• Research in Plant Disease
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• v.12 no.3
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• pp.278-283
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• 2006

The effect of calcium cyanamide($CaCN_2$) on suppression of clubroot of Chinese cabbage was evaluated in the fields infested with Plasmodiophora brassicae at National Institute of Highland Agriculture, Pyeongchang, Korea, from 2002 to 2003. Calcium cyanamide was found to be more effective in reducing disease severity than flusulfamide dust powder. The optimal dosage of calcium cyanamide for control of clubroot of Chinese cabbage was 61 kg/10a. When calcium cyanamide was incorporated into soil at 5, 10, 15 and 20 days before planting(DBP), maximum disease suppression was obtained in the plot with calcium cyanamide, applied 5DBP. The fertilizer property of calcium cyanamide as a nitrogen fertilizer was also investigated by comparing with urea on cv. CR Gangta, a resistant variety of Chinese cabbage. The nitrogen uptake in calcium cyanamide treatment(17.6 kg/10a), was not significantly different from that of urea(17.8 kg/10a). These results indicated that calcium cyanamide could be used as a soil disinfectant as well as a nitrogen fertilizer.

• Research in Plant Disease
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• v.16 no.1
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• pp.90-93
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• 2010

Sclerotinia rot occurred sporadically on the stems and leaves of Astragalus sinicus in the farmers fields at Goseong-gun, Gyeongnam province in Korea. The infected plants showed the typical symptoms: watersoaked, wilt, rot, blight and eventual death. The colony of the isolated fungus on potato-dextrose agar (PDA) was white to faintly gray color. Sclerotia formed on the PDA were globose in shape, black in color and $2{\sim}14{\times}2{\sim}7mm$ in size. The optimum temperature for mycelial growth and sclerotium formation was at $20^{\circ}C$ on PDA. Apothecia formed on PDA were globose~disk in shape and 3~8 mm in size. Asci were cylindrical in shape and $145{\sim}210{\times}10{\sim}12{\mu}m$ in size. Ascospores were ellipsoid and $10{\sim}14{\times}6{\sim}7{\mu}m$ in size. On the basis of mycological characteristics and pathogenicity test on host plants, the fungus was identified as Sclerotinia trifoliorum Eriksson. This is the first report on sclerotinia rot of A. sinicus caused by Strifoliorum Eriksson in Korea.

• The Korean Journal of Mycology
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• v.40 no.2
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• pp.124-126
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• 2012

Stem rot symptoms of Eupatorium lindleyanum occurred sporadically in the herb exhibition field at Hamyang-gun Gyeongsangnam-do Agricultural Research and Extension Services in Korea. The typical symptom included water-soaking on the main stem, rotting, wilting, and blighting, which eventually leads to death of the plant. The sclerotia, white to brown, globoid with size of 1-3 mm, were formed over lesions and surface soil line. The optimum temperature for mycelial growth and sclerotia formation was $30^{\circ}C$ on PDA. The typical clamp connections were observed in the hyphae of the fungus grown on PDA. Mycological characteristics and pathogenicity to host plants indicated that the infected fungus was Sclerotium rolfsii Saccardo. This is the first report of stem rot on Eupatorium lindleyanum caused by S. rolfsii in Korea.

• Research in Plant Disease
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• v.19 no.3
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• pp.233-236
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• 2013

This research was conducted to investigate the incidence of viral infection in Samcheok-shi and Jeongseon-gun, main garlic growing areas of Gangwon province in Korea. Four primers sets (GLV, LYSV, GCLV, OYDV) were used for RT-PCR to test of 100 samples collected from each location. Infection rates of GLV, LYSV, GCLV and OYDV of garlic samples from Samcheok-shi and Jeongseon-gun were 95, 95, 92 and 33%, respectively. All garlic samples tested in this research were infected at least one virus. Coinfection of 3 kinds of virus (GLV, LYSV and GCLV) and 4 kinds of virus (GLV, LYSV, GCLV and OYDV) were 60 and 25%, respectively. While infections of GLV, LYSV and GCLV were evenly found in both two regions, OYDV infection of garlic samples collected from Jeongseon-gun was higher than Samcheok-shi. Viral infections at garlic fields of whole country and Gangwon province are very serious now. Therefore, it is very necessary to develop technic for virus-free bulb and renew seed bulb of garlic.

• Research in Plant Disease
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• v.12 no.1
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• pp.28-31
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• 2006

One of major potato viruses is Potato virus Y (PVY) in Korea. In the southern part of Korea, potatoes have been grown as double crops in a year by using cv. 'Dejima' and 'Chubak' due to very short dormancy. However, they have caused a serious problem such as a rapid degeneration. It has been thought that the degeneration is affected by the high incidence of PVY in neighboring potato fields. Therefore, the investigation of factors causing the degeneration is very important in the production of healthy seed potato. In this study, the PVY reinfection rates of several potato varieties and the different seed sources of cv. 'Chubak' have been investigated. Results show that the lowest infection rate of PVY among four potato cultivars derived from minitubers is cv. 'Superior'. The others are in order of 'Dejima', 'Atlantic' and 'Chubak'. Also, the incidences of PVY differ significantly when several seed sources are examined. When the seed potatoes (G2, the progeny of microtuber) as spring potato crops are planted in area without potato field nearby, the infection rate of PVY is as low as that of microtubers. However, PVY incidence in the progenies of minitubers as fall potato crops largely increases. Therefore, the best way of potato production under double cropping system is to use the healthy seed potato produced in area without potato field and plant relatively resistant cultivar such as Dejima.