• Research in Plant Disease
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• v.10 no.2
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• pp.135-137
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• 2004

It was conducted to select the resistant potato cultivars to common scab, to replace the existing susceptible cv Dejima in Jeju island conditions both 1997 and 2001. Among cultivars, cvs Jemchip, Alpa, Atlantic and Jopung were more resistant than others in the field with both low and high incidence of the disease. Also among the existing cultivars grown in Korea, cvs Superior, Jopung and Chubaek were resistant, expecially in terms of production of marketable potatoes.

• Journal of Environmental Science International
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• v.32 no.11
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• pp.777-788
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• 2023

Potato common scab disease is caused by pathogens belonging to Streptomyces spp. and results in a serious yield loss worldwide. Despite decades of research aimed at disease management, a definitive control method remains undiscovered. This study aims to explore the correlation between the C/N ratio and urea application with potato common scab pathogen dynamics and disease severity. We applied sawdust with a high C/N ratio and urea into the soil prior to potato cropping, both in pot and field experiments. Disease severity assessments and quantification of the TxtB gene were conducted at the harvest stage. Furthermore, culture experiments were performed to assess the direct impact of urea on the pathogen. Our findings revealed that higher disease severity was correlated with a high C/N ratio application and pathogenic gene quantity. Urea exhibited a direct influence on S. scabiei activity, reducing the disease severity in pot experiments. However, the effects of urea application on disease suppression in the conductive field were inconclusive. Although the results of urea application experiments displayed inconsistencies between pot and field trials, urea worked as the control to suppress S. scabiei activity. Further investigations are needed under various field conditions to confirm these findings.

• Research in Plant Disease
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• v.10 no.2
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• pp.138-141
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• 2004

It was conducted to find out the effect of chemical treatment on seed tubers and soil to control potato common scab in Jeju Island in 2001. Although the treatment of soil disinfection with Dazomet Gr. (30kg/10a) was more effective comparing to the treatment of seed disinfection and the untreated, the control value was merely 40.5%. However, the combined treatment of soil and seed disinfection was considerably more effective to reduce the percentage of infection and infection area, and increase the production of marketable tubers and also increase the control value. Therefore, the combined treatments are demanded to reduce the scab incidence in Jeju field conditions.

• Research in Plant Disease
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• v.9 no.3
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• pp.137-144
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• 2003

This study was conducted to clarify developmental characteristics of scab in potato fields in Jeju island, Korea from 1995 to 1999. Occurrence of potato scab increased with repeated cultivaton of potato and high soil pH in the fields. Incidence of the disease was high as 54.8％ in the repeatedly cultivated potato fields but relatively low as 20.8~26.3% in the non-cultivated fields and in the fields where barley and Chinese cabbage were formerly cultivated. A total of 66 isolates were obtained from the diseased patato tubers and identified as Streptomyces scabies, S.turgidiscabies and S. acidiscabies. The isolation frequency of each Streptomyces species was 37.7%, 14.8% and 18.0%, respectively. The optimum temperature for mycelial growth of the Streptomyces spp. was $28~30^{\circ}C$, and the optimum pH for that 6~7.

• 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.

• Research in Plant Disease
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• v.11 no.1
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• pp.66-71
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• 2005

The effect of medium components such as wheat bran, rice bran, oat meal, and soybean meal as basic ingredients and KH2PO4, glucose, and molasses as additives on mass production and anti-potato common scab activ ity of a streptomycete A020645 strain as a biocontrol agent (BCA) candidate was investigated. Of basicingredients, oat meal was the best one for mass poduction and enhancement of anti-potato common scabactivity. The biomass production of the active strain was more enhanced when 0.1-0.01.% glucose or molassesas additive were added into the basic medium. These information may have important implications in applying for effective formulation of BCA.

• Korean Journal of Plant Resources
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• v.22 no.6
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• pp.483-488
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• 2009

The main objective of this breeding program is to develop high yielding, disease resistance and good processing potato cultivar. 'Gui Valley' is a clonal selection resulting from a cross between 'ND2471-8' and 'Cona'. It has medium plant height and light green foliage. 'Gui Valley' has medium flowering habit and light pink flowers. 'Gui Valley' is a medium maturing potato cultivar and tubers are smooth, yellow skin, light yellow flesh, long-oval tuber shape, distinct red eyes with medium depth and medium dormancy. It has high level of tuber uniformity and good keeping quality. 'Gui Valley' demonstrates resistance to potato virus Y (PVY), soft rot, but moderately susceptible to late blight and common scab. It is also resistant to most of the internal and external physiological disorders particularly dehiscence, hollow heart and internal brown spot. The specific gravity of 'Gui Valley' is significantly higher (1.097) than that of 'Shepody' (1.078). 'Gui Valley' has suitable for processing mainly French fries and chips. This cultivar has high level of tuber uniformity and capable of yielding 37.6 $t{\cdot}ha^{-1}$, which is 18.2% higher than the control potato cultivar 'Shepody' under optimum agronomical practices.

• The Plant Pathology Journal
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• v.20 no.2
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• pp.115-126
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• 2004

The actinomycete strain PK-A41 was isolated from a soil sample from pepper fields in Ko-yang, Korea. The strain PK-A41 inhibited the mycelial growth of some plant pathogenic fungi and oomycete, Alternaria mali, Colletotrichum orbiculare, Fusarium oxysporum f.sp. lycopersici, Magnaporthe grisea, Rhizoctonia solani, and Phytophthora capsici. The presence of LL-diaminopi-melic acid in the cell wall extract and the nucleotide sequence of the 16S rDNA region of the strain PK-A41 was assigned to Streptomyces scabiei. Further morpho-logical, biochemical, and pathological analyses also confirmed the strain PK-A41 to be S. scabiei, which is pathogenic to potato tubers. The maximum antibiotic production of the strain PK-A41 was achieved when grown on the glycerol peptone broth (GPB) medium for 9 days.