• Research in Plant Disease
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• v.24 no.1
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• pp.52-58
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• 2018

Pear scab and rust are the major diseases causing severe epidemics in organic cultivation of pear trees. Incidences of pear scab and rust were compared in organically managed plots and conventionally managed plots to obtain optimum application schedule of environment-friendly control agents in organically managed plots. Organically cultural practice with 10 time-applications of lime sulfur and Bordeaux mixture showed higher than 40% of control efficacies of pear scab and rust compared to conventionally cultural practice. Organically cultural practice with 8 time-applications of lime sulfur considering weather condition showed higher than 30% of control efficacies of pear scab compared to conventionally cultural practice. The results suggest that proper application of environment-friendly control agents such as lime sulfur considering weather condition will enable effective control of the major diseases for organic cultivation of pear.

• 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 Microbiology and Biotechnology
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• v.25 no.11
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• pp.1782-1786
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• 2015

A new improved PCR method has been developed for the rapid, reliable, and sensitive detection of Venturia nashicola, a destructive pathogen of scab disease in Japanese pear. The translation elongation factor-1 alpha gene-derived PCR primers specifically amplified a 257-bp-sized DNA band of the target gene from the genomic DNA of V. nashicola. No amplicon was produced from the genomic DNA of other Venturia spp. and reference fungal species tested. With the high detection limit of 10 fg DNA content, our real-time method could be used for the quarantine inspection and field monitoring of V. nashicola.

• 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.

• Korean Journal of Microbiology
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• v.54 no.2
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• pp.158-160
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• 2018

Streptomyces sp. P3 was isolated from potato scab diseased tubers in Pyeongchang, Gangwon-do, Republic of Korea in 2017. Here, we report the draft genome sequences of P3 with 9,851,971 bp size (71.2% GC content) of the chromosome. The genome comprises 8,548 CDS, 18 rRNA and 66 tRNA genes. Although strain P3 did not show pathogenicity both potato tuber assay and radish seedling assay, it possesses tomatinase (tomA) gene among conserved pathogenicity-related genes in well characterized pathogenic Streptomyces. Thus, the genome sequences determined in this study will be useful to understand for pathogenic evolution in Streptomyces species, which already adapted to potato scab pathogens.

• Mycobiology
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• v.47 no.1
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• pp.76-86
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• 2019

Scab disease caused by Venturia nashicola is of agroeconomic importance in cultivation of Asian pear. However, little is known about the degree of genetic diversity in the populations of this pathogen. In this study, we collected 55 isolates from pear scab lesions in 13 major cultivation areas in Korea and examined the diversity using sequences of internal transcribed spacer (ITS) region, ${\beta}$-tubulin (TUB2), and translation elongation factor-$1{\alpha}$ ($TEF-1{\alpha}$) genes as molecular markers. Despite a low level of overall sequence variation, we found three distinctive subgroups from phylogenetic analysis of combined ITS, TUB2, and $TEF-1{\alpha}$ sequences. Among the three subgroups, subgroup 1 (60% of isolates collected) was predominant compared to subgroup 2 (23.6%) or subgroup 3 (16.4%) and was distributed throughout Korea. To understand the genetic diversity among the subgroups, RAPD analysis was performed. The isolates yielded highly diverse amplicon patterns and none of the defined subgroups within the dendrogram were supported by bootstrap values greater than 30%. Moreover, there is no significant correlation between the geographical distribution and the subgroups defined by molecular phylogeny. Our data suggest a low level of genetic diversification among the populations of V. nashicola in Korea.

• 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.

• Korean Journal of Organic Agriculture
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• v.28 no.2
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• pp.223-233
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• 2020

The aim of the present study was to investigate the suppressive effects of the bio-sulfur used by eco-friendly farms on the outbreak of citrus scab. To evaluate the inhibiting effect of bio-sulfur on citrus scab germ tube growth, the citrus scab pathogen Elsinoe fawcettiiwas cultured in PDB and agar media, and germ tube growth was observed after bio-sulfur treatment. At both 40 and 88 h after inoculation, germ tube formation was inhibited by 500-, 1000-, and 2000-fold diluted bio-sulfur, and at dilutions above 4000-fold, germ tube formation was observed, although growth was still inhibited, when compared to untreated cultures. Meanwhile, the occurrence of citrus scab on spring-flush leaves in the field was 40.3% in the untreated control and 5.3, 10.3, 12.3, 15.3, and 24.0% when treated with imibenconazole, 2-4 and 6-6 lime-Bordeaux mixtures, which are also used by eco-friendly farms, 500-fold diluted bio-sulfur, lime sulfur, and 1000-fold diluted bio-sulfur, respectively. The occurrence of citrus scab on citrus fruit was 79.3% in the untreated control and 4.0, 33.8, 42.0, 43.3, 44.8, and 78.0% when treated with imibenconazole, 2-4 lime-Bordeaux mixture, 6-6 lime-Bordeaux mixture, 500-fold diluted bio-sulfur, lime sulfur, and 1000-fold diluted bio-sulfur, respectively. Because citrus scab can infect citrus leaves as early as May, as the spring flush begins, preventative control should be implemented by mid- to late-April, thereby increase disease control and reducing both labor and farming costs.

• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.719-730
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• 2014

This study was conducted to select proper soil amendments in order to reduce the occurrence of potato scab and maintaining soil health by applications of dolomitic lime, sulfur, potassium sulfate, shell meal fertilizer, silicate fertilizer, lime nitrogen and ammonium sulfate fertilizer in different pH levels of volcanic ash soil with continuous cultivation of potato. In potassium sulfate-applied plot with a low soil pH, the incidence rate and disease severity of scab were lowest at 84.4% and 28.4%, respectively. Those were lowest among the treatments. Value of potato scab control was 12.3% and marketable yield of potato was highest at 93.2%. In lime nitrogen-applied plot (60 kg/10a), the incidence rate was low at 38.3%, and control value was 23.8% and marketable yield of potato was high at 66.3%. In relatively higher pH soils, the incidence rate of scab was lowest at 38.3% in the lime nitrogen-applied plot (60 kg/10a). Value of potato scab control was 23.8%, which was four times higher than that in sulfur-applied plot. Marketable yield of potato was highest at 66.3% in the lime nitrogen-applied plot. In the lime nitrogen plot infected with potato scab pathogen such as S. acidiscabies and S. scabiei were remarkably lower than other soil amendments at 2.5, 5, and 10 g/L concentrations of lime nitrogen using Glucose Yeast Malt (GYM) medium. In conclusion, this study suggests that potassium sulfate application in low pH soil (less than pH 5) and lime nitrogen application in relatively higher pH soil (more than pH 6) before potato seeding might be helpful to reduce the occurrence of potato scab.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.401-406
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• 2010

This study was conducted to investigate the control effects of the environmental-friendly materials against major diseases of pear and to elucidate factors related to spore disperse of pear scab and pear rust. Spore disperse was deeply related ambient temperature in the early stage of disease occurrence and the maximum spore disperse was affected greatly by the air humidity, Percent of infected leaves of pear scab in plot treated with Trichoderma harzianum-YC459 was 29.3% and 43.3% in plot treated with Sulfur-80%. Two formulations above-mentioned were less effective to control pear scab than the chemical pesticide, hexaconazole. Control effect in plots single- and mixed-treated with Trichoderma harzianum-YC459, Sulfur-80% and hexaconazole against pear scab were compared with that in plot treated with chemicals by conventional application schedule in pear orchard. The incidence of pear scab was lower in plot treated with the environmental-friendly materials than that of untreated plot. However there was no significant difference among the treatments at the 5% level. Application of Sulfur-80% reduced significantly the incidence of pear scab (7.8%) compared to that (10.3%) in plot treated by conventional application schedule in organically cultivated pear orchard. Alternative application of Trichoderma harzianum-YC459 and Sulfur-80% (4.3%) suppressed the incidence of pear rust than that (7.1%) in plot treated by conventional application schedule in organically cultivated pear orchard.