• Mycobiology
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• v.38 no.2
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• pp.156-158
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• 2010

Stem rot disease was found in garlic (Allium sativum L.) cultivated from 2008 to 2010 in the vegetable gardens of some farmers in Geumsan-myon, Jinju City, Gyeongnam province in Korea. The initial symptoms of the disease were typical water-soaked spots, which progressed to rotting, wilting, blighting, and eventually death. White mycelial mats had spread over the lesions near the soil line, and sclerotia had formed over the mycelial mats on the stem. The sclerotia were globoid in shape, 1~3 mm in size, and tan to brown in color. The optimum temperature for growth and sclerotia formation on potato dextrose agar (PDA) medium was $30^{\circ}C$. The diameter of the hyphae ranged from approximately 4 to $8\;{\mu}m$. Typical clamp connection structures were observed in the hyphae of the fungus, which was grown on PDA medium for 4 days. On the basis of the mycological characteristics and pathogenicity of the fungus on the host plants, the causal agent was identified as Sclerotium rolfsii Saccardo. This is the first report of stem rot disease in garlic caused by S. rolfsii in Korea.

• Korean Journal of Microbiology
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• v.3 no.1
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• pp.24-26
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• 1965

In July, 1963, a virulent outbreak of late blight in the potato field of Daekwanlyung area was studied and it was known as epidemics. Two stocks are $T_1$ and $T_1$ of Phytophthora infestans (Mont.) De Bary which isolated from Irish Cobbler were inoculated at field and green house respectively by cutted leaves method. Two strains have been distinguished in reactions to leaves: $T_1$: Irish Cobbler (r), Morin No. 1 (r) have shown infectivity of disease and Kennebec ($R_1$), 1512-C(16) ($R_2$), Pentland Ace ($R_3$) and Hokkai No. 17 ($R_4$) have not shown infectivity of disease; $T_1$: Irish Cobbler (r), Norin No. I (r) and Kennebec ($R_1$) have shown infectivity of disease and 1512-C (16) ($R_2$), Pentland Ace ($R_3$) and Hokkai No. 17($R_4$) have not shown infectivity of disease. Both are the first record of race O and race 1 of Phytophthora infestans (Mont.) De Bary in Korea.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.134.2-135
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• 2003

The plant-pathogenic species S. scabies, S. acidiscabies, and S. turgidiscabies cause the scab disease of potato and produce the phytotoxins, thaxtomins. necl, a gene conferring a necrogenic phenotype, is involved in pathogenicity and physically linked to the thaxtomin A biosynthetic genes. Identification of the pathogenic strains of Streptomyces from soil was performed through the polymerase chain reaction by using specific pathogenicity primer sets derived from the necl gene sequences of Streptomyces smbies. The DNA was extracted from soil using a bead-beating machine and modifications of the FastPrep system. The DNA was suitable for direct use in the PCR. The PCR products showed the bands of approximately 460 bp. This methods can be very usuful in identifying species responsible for scab diseases and studying on the ecology of plant-pathogenic Streptomyces spp.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.1
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• pp.84-89
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• 1994

Potato virus Y (PVY) is an important viral disease in burley tobacco in Korea and is mostly transmitted by green peach aphid, Myzus penicae, in nature. Effects of barrier nets on the immigration of the aphid population into tobacco fields and on the control of PVY were investigated in 3 tobacco fields with 1.8 m - height polyethylene (PE) nets on their outer - sides in Iseo - Myeon, Wanju - Kun, Cheonbuk. Immigration of aphids to the tobacco yields started at late April and reached maximum at early June. The immigrating aphid population was apparently blocked by the barrier nets to be reduced by 54-73%. PVY severity was also reduced by the barrier nets. However, the control value was variable, ranging 24-67%, which suggests that effect of the PE net barrier on the prevention of aphid-borne virus might be variable depending on the location and slope of the fields.

• Research in Plant Disease
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• v.18 no.2
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• pp.117-122
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• 2012

In 2006, the effect of soil pH adjustment on control of common scab of potato caused by Streptomyces spp. was evaluated in the field. Soil with an original pH 5.7 was treated with sulfur of 42 kg/10a and calcium hydroxide of 81.6 kg/10a and 184.5 kg/10a to adjust pH 5.0, 6.0 and 6.5, respectively. Additionally, the effect of gypsum (522 kg/10a) on soil pH and disease severity was examined. The soil pH of sulfur treatment plot was continuously declined from 5.13 at tuber initiation time to 5.01 at harvest. The disease severity of sulfur treatment plot was relatively low (22.8%) and the marketable yield of that was high (90.5%). By contrast, the soil pHs treated with calcium hydroxide (81.6 kg/10a and 184.5 kg/10a) were increased (pH 6.06 and 6.49, respectively) at harvest. In addition, calcium hydroxide treatment plots showed higher disease severities (51.0% and 61.1%), and lower marketable yields (55.7% and 37.0%). Meanwhile, the soil pH of gypsum treatment plot was not changed until harvest, and the disease severity and the marketable yield were not significantly different from those of control. The effect of crop rotation was also evaluated with four crops such as welsh onion, soybean, corn and Chinese cabbage. These crops were planted in the infested field from 2005 to 2007, and potatoes were planted in the same field in 2008. The disease severities of potatoes produced after rotations with welsh onion, soybean, corn and Chinese cabbage for 3 years were 13.1%, 16.7%, 28.9% and 30.2%, respectively. However, the disease severity of 73.1% was shown in continuous cropping of potato for 3 years. In addition, similar effects were exhibited in the marketable yield. These results demonstrate that the adjustment of soil pH and crop rotation might be very useful tools to control common scab of potato.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.309-309
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• 2017

The experiments were carried out in open experimental field of Field Crops Research Institute, Hai Duong, Vietnam in Winter Spring seasons 2015-2016 and 2016-2017 for finding high yielding of Korean chipping potato varieties which are adaptable to Vietnam condition. Six varieties of Korean potato (G1, G2, G4, G10, B1, B2) were experimented. The control variety (G6) was Atlantic which has long been a standard chip variety. The results showed that, for a hill, there was positive correlation between number of stems and number of tubers. The hill yield also showed highly relation to the plant height and number of tubers. Even though the growth and yield of potatoes grown in the season 2016-2017 were significant higher than these of potatoes grown in the season 2015-2016, their percentages of tubers infected by scab disease were much higher. This is probably because of irregular soil moisture content at the tuber forming duration. While G1, G6 and B1 are white flesh varieties, the remaining are yellow flesh varieties. There are two shapes types among experimented varieties: oblong (G1, G10, B1) and round shape (G2, G4, G6, B2). The total yields of varieties G1, G2, B1, B2 were higher than the total yield of the control variety from 16.5-49.4% in the season 2015-2016 and from 39.8-75.6% in the season 2016-2017.

• Research in Plant Disease
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• v.10 no.2
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• pp.142-144
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• 2004

Effect of potassium phosphonate on control of potato basal stem rot caused by Pythium myriotylum in hydroponics system was evaluated at spring and fall cultivation in Jeju island in 2001. Potassium phosphonate 200 ppm treatment, which was directly supplemented into the nutrient solution, showed 90.5%, and 100 ppm treatment showed 50.5% control value in spring cultivation. Fall cultivation, potassium phosphonate 200 ppm treatment showed 100%, and 100 ppm treatment showed 69.9% control value. Potassium phosphonate 200 ppm treatment, basal stem rot of potato started to develop 10 days ofter inoculation into the hydroponics system showed 8.0% in infection rate. Potassium phosphonate 100 ppm treatment, after 5 days showed 10.0%, and after 10 days showed 20.0% infection rate, but the non-treated was after 5 days showed 56.7%, and after 10 days showed 96.9% infection rate.

• Research in Plant Disease
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• v.19 no.2
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• pp.118-120
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• 2013

During the early spring of 2007 to 2009, stem rot of sweet potato (Ipomoea batatas L.) caused by Sclerotium rolfsii occurred in seedling stage grown in plastic film house at Iksan. In seedling stage of sweet potato, symptoms were initially appeared in yellowing and then the seedlings were eventually wilted. The fungus produced abundant white silky mycelium on infected tissues and soil line. Seedlings were very susceptible and died quickly once they were infected. The whole area of a petridish was rapidly covered with white mycelium on agar medium. Sclerotia began to produce after 7 days of mycelial growth and white sclerotia quickly melanized to a dark brown coloration. The causal agent isolated from the diseased plants was identified as Sclerotium rolfsii Saccardo on the basis of the morphological and cultural characteristics. All isolates of S. rolfsii caused similar symptoms on the host petioles by artificial inoculation.

• Plant Resources
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• v.8 no.3
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• pp.202-208
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• 2005

Osmotic stress is one of major limiting factors in crop production. In particular, seasonal drought often causes the secondary disease in the field, resulting in severe reduction in both quality and productivity. Recent efforts have revealed that many genes encoding protein kinases play important roles in osmotic stress signal transduction pathways. Previously, the AtSIK (Arabidopsis thaliana Stress Inducible Kinase) mutants have shown to enhance tolerance to abiotic stresses, accompanying with higher expression of abiotic stress-related genes than did the wild-type plants. In this study, we have transformed potato (cv. Taedong Valley) with the AtSIK expression cassette. Both PCR and RT-PCR using AtSIK-specific primers showed stable integration and expression of the AtSIK gene in individual transgenic lines, respectively. Foliar application of herbicide ($Basta^{(R)}$) at commercial application rate (0.3% (v/v)) revealed another evidence of stable gene introduction of T-DNA which includes the bar gene for herbicide resistance. Overexpression of the AtSIK gene under dual CaMV35S promoter increased sensitivity to salt stress (300 mM NaCl), which was demonstrated by the reduction rate of chlorophyll contents in leaves of transgenic potato lines. These results suggest that possible increase of osmotic tolerance in potato plants may be achieved by antisense expression of AtSIK gene.

• Research in Plant Disease
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• v.17 no.2
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• pp.225-227
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• 2011

The stem rot of Chrysanthemum zawadskii var. latilobum occurred in the landscape field of Sanggwan-myeon, Wanju-gun, Jeonbuk, Korea in September 2009. The typical symptoms of the disease were water-soaking and dark brown rot on the stem, wilting and blighting. Most infected plants died of the disease. White mycelial mats were spread over lesions and brown sclerotia were formed on stems and near soil surface. The sclerotia were spherical or irregular, 0.8-3.5 (mean 1.8) mm in size on potato dextrose agar, brown in color. The optimal temperature range of hyphal growth was $25-30^{\circ}C$ and the hyphal diameter was 4-9 ${\mu}m$. Clamp connections were observed in the hyphae of the fungus grown on potato dextrose agar. Pathogenicity of the casual organism was provided on C. zawadskii according to Koch's postulate. The fungus was identified as Sclerotium rolfsii on the basis of mycologiclal characteristics and pathogenicity test to host plants. This is the first report on the stem rot of C. zawadskii caused by S. rolfsii in Korea.