• 한국균학회지
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• 제11권2호
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• pp.99-101
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• 1983

Black root rot caused by Cylindrocladium crotalariae is one of the most serious soilborne disease in soybean. Plant height reduction of Hwangkeum Kong was 38% by the rotting of the whole main root and 9% by rotting of the half of the main root as compared with partial discoloration in the main root. Pod number per plant and seed weight were significantly reduced by the increase of the disease severity. Important yield components such as number of pods per plant and seed weight were negatively correlated with the soybean black root rot severity.

• The Plant Pathology Journal
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• 제25권1호
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• pp.1-5
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• 2009

Root rot caused by Cylindrocarpon destructans is one of the most important diseases of ginseng (Panax ginseng C. A. Meyer). Two types of symptoms found in ginseng root rot are black root rot and rusty root (rusty spots), in which disease severities are high and low, respectively. Symptom development and related histopathological changes were examined in an inoculation test on 2-year-old ginseng roots using virulent (Cy9801) and avirulent (Cy0001) isolates of C. destructans under different temperature conditions (13, 18, 23, and $28^{\circ}C$). Black root rot was only induced by Cy9801 in the lower temperature range (13, 18, and $23^{\circ}C$) and not at the higher temperature ($28^{\circ}C$). No black root rot, but only rusty spot symptoms, were induced by Cy0001 at all temperatures tested except $13^{\circ}C$, at which no symptoms occurred on over half of inoculation sites, suggesting disease development was influenced by pathogen virulence and temperature. Wound periderms were formed in all root tissues with rust spot symptoms at $28^{\circ}C$ caused by Cy9801 and at 18, 23, and $28^{\circ}C$ temperatures caused by Cy0001. No wound periderm was formed at $13^{\circ}C$ by either Cy9801 or Cy0001. Light microscopy revealed that the wound periderm was formed by initial cell divisions in cell wall formation and/or additional cell wall layering in parenchyma cells without obvious nuclear division, followed by layering of the divided cells adjacent to the inoculation sites, blocking the spread of the rot. These results suggest that disease development declined at lower temperatures and by the formation of a wound periderm at higher temperatures, and that ginseng rusty root may develop under conditions unfavorable for further disease development of C. destructans.

• Journal of Ginseng Research
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• 제5권1호
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• pp.73-84
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• 1981

Effect of environmental factors and host on the growth and outbreak of various ginseng diseases was reviewed Environmental lectors included hydrogen ion concentration, moisture content, temperature, nutrition, and microbiol populations. Age of the ginseng plants in relation to several ginseng disease occurrence was also included in order to formulate the effective control measure for ginseng diseases. Damping-off caused by Rhizoctonia, Pythium, and Phytophthora, greymold by Botrytis, sclerotinia by Scleretinia, and phytophthora blight caused by Phytophthora were usually prevalent during the early growing season of ginseng when temperature is below 20$^{\circ}C$, while anthrac se caused by Colletotrichum, alternaria blight by Alternaria, and bacterial soft rot by Erwinia were so during the latter growing season when temperature is above 25$^{\circ}C$. However, the root rot incited by Fnarium and Cylindrocarpon caused severe damages throughout the growing season. Growth range of the temperature for a pathogen was highly related to the corresponding disease outbreak. Hydrogen ion concentration was highly related to the outbreak of sclerotinia, root rot, and red rot. Most severe outbreak of those diseases where the soil acidity was pH 4.7, pH 6.5- 7.5, and pH6.0-6.5, respectively. Nitrogen content in the soil was also related to outbreak of root rot and red rot. More red rot occurred where NH,-nitrogen is above 30 ppm and more root rot obtained when excessive nitrogen fertilizer applied. Yellow necrosis apparently was related to magnesium especially its ratio with potassium or calcium content in a soil. Fusarium Population showed significant .relations to missing rate of ginseng Plants in a Implanting ginseng field, while that of total bacteria showed similar relations in all ginseng field, However, in six year old ginseng fields, the more the Streptomyces population was, the less the Fusarium obtained. Consequently, less missing rate observed in a field where Streptomyces population was high. Damping-off, root rot, Rhytophthor a blight were mose severe on the nursery and on 2-3 years old ginseng plants, whereas sclerotinia, and grey cod, alteraria blight, anthracnose were severe on 4-6 years old ginseng plants. Root rot caused by Fusarium and Erwinia, however, was also severe regardless of the age of the plants when the roots were injured. Therefore, for the effective control of ginseng root rot most careful control of the disease during the early year should be rendered.

• International Journal of Industrial Entomology and Biomaterials
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• 제16권2호
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• pp.49-56
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• 2008

A preliminary survey on the incidence and intensity of root disease complex (association of Meloidogyne incognita and root rot pathogens) was carried out in the sericultural areas of Karnataka. A total of 280 mulberry gardens were surveyed in 14 districts of Karnataka belonging to different types of soil (red sandy, red loamy and black cotton), farming systems (irrigated and rainfed), varieties (V-1, K-2, Local and S-13) and age of the plants (0-5, 5-10 and 10-15 years). It was observed that the association of M. incognita with Botryodiplodia theobromae and Fusarium solani causes the root disease complex in mulberry. Of the 280 gardens visited, 94 were infested with the disease complex and incidence was recorded as 33.6%. The higher intensity of root disease complex was observed when the root system had more than 100 galls/plant with infection of mixed population of B. theobromae and F. solani in sandy soil under irrigated farming. The 5-10 years old mulberry plantation with V-I variety was found to be most susceptible to root disease complex. Districts like Mysore, Kolar, Mandya, Tumkur, Chitradurga and Bangalore were observed as sensitive areas. Further, the wounds caused by M. incognita in mulberry roots favour the easy entry of root rot pathogens, which increased the severity of the disease very fast.

• Journal of Ginseng Research
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• 제42권1호
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• pp.9-15
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• 2018

Cylindrocarpon destructans/Ilyonectria radicicola is thought to cause both rusty symptom and root-rot disease of American and Korean ginseng. Root-rot disease poses a more serious threat to ginseng roots than rusty symptoms, which we argue result from the plant defense response to pathogen attack. Therefore, strains causing rotten root are characterized as more aggressive than strains causing rusty symptoms. In this review, we state 1- the molecular evidence indicating that the root-rot causing strains are genetically distinct considering them as a separate species of Ilyonectria, namely I. mors-panacis and 2- the physiological and biochemical differences between the weakly and highly aggressive species as well as those between rusty and rotten ginseng plants. Eventually, we postulated that rusty symptom occurs on ginseng roots due to incompatible interactions with the weakly aggressive species of Ilyonectria, by the established iron-phenolic compound complexes while root-rot is developed by I. morspanacis infection due to the production of high quantities of hydrolytic and oxidative fungal enzymes which destroy the plant defensive barriers, in parallel with the pathogen growth stimulation by utilizing the available iron. Furthermore, we highlight future areas for study that will help elucidate the complete mechanism of root-rot disease development.

• 한국식물병리학회지
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• 제14권3호
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• pp.209-211
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• 1998

Black dot root rot occurred severely in greenhouse tomatoes in jangseong area of Korea in April, 1996. The causal fungus of the disease was identified as Colletotrichum coccodes based on the morphological and cultural characteristics. Pathogenicity tests revealed that isolates of the fungus were responsible for the disease, and two cultivars of cherry tomato were less susceptible to the disease than other cultivars of tomato and cherry tomato tested.

• Journal of Ginseng Research
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• 제19권2호
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• pp.175-180
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• 1995

The disease development of root-rot [pathogen:Cylindrocarpon destruction (Zinssm.) Scholten] occurred in 2-year old ginseng (Panax ginseng C.A. Meyer) was investigated in the continuous (the first cultivation: 1978∼1982, 2nd cultivation: 1990∼1993 and abolished in 1993 due to replanting problem) and replanted cultivation (period of cultivation: 1980∼1984). In the continuous cultivation, incidences of root-rot were 0.7% on May 3, 48.6% on May 24, and 95.8% on June 14, respectively. In the replanted cultivation, no symptom was observed on May 3 and disease incidence was generally lower compared with the continuous cultivation. On the aerial part of the ginseng infected by C. desiccates, the end and/or margin of leaves were changed to dark reddish color that appeared for behind the root-rot symptom. In this field, the longitudinal growth of lateral root was more inhibited than in the case of the replanted cultivation by C. destmctans. The inhibition rate of rootlet growth was 37.3% in the continuous cultivation as compared with that of replanted cultivation at June 14. Though lesions of root-rot were formed all over the roots, 61.2% of the lesions was positioned within 6 cm under the rhizome. Key words Panax ginseng, Cylindrocarpon destmtan, root-rot of ginseng, replanting problem of ginseng.

• 한국균학회지
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• 제50권1호
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• pp.41-46
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• 2022

Gastrodia elata infected with root rot disease was collected from cultivated G. elata fields in Gimcheon, Korea, in 2018. G. elata tuber surfaces exhibited root rot disease symptoms of dark-grey lesions and white fungal mycelial growth. The fungus was isolated from symptomatic tubers and cultured. Based on morphological characteristics and molecular analysis of the internal transcribed spacer region of ribosomal DNA and translation elongation factor 1-alpha, the isolated fungus was Fusarium oxysporum. This is the first report of root rot caused by F. oxysporum on G. elata tubers in Korea.

• Journal of Ginseng Research
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• 제45권1호
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• pp.156-162
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• 2021

Background: It is estimated that 20-30% of ginseng crops in Canada are lost to root rot each harvest. This disease is commonly caused by fungal infection with Ilyonectria, previously known as Cylindrocarpon. Previous reports have linked the virulence of fungal disease to the production of siderophores, a class of small-molecule iron chelators. However, these siderophores have not been identified in Ilyonectria. Methods: High-resolution LC-MS/MS was used to screen Ilyonectria and Cylindrocarpon strain extracts for secondary metabolite production. These strains were also tested for their ability to cause root rot in American ginseng and categorized as virulent or avirulent. The differences in detected metabolites between the virulent and avirulent strains were compared with a focus on siderophores. Results: For the first time, a siderophore N,N',N"-triacetylfusarinine C (TAFC) has been identified in Ilyonectria, and it appears to be linked to disease virulence. Siderophore production was suppressed as the concentration of iron increased, which is in agreement with previous reports. Conclusion: The identification of the siderophore produced by Ilyonectria gives us further insight into the root rot disease that heavily affects ginseng crop yields. This research identifies a molecular pathway previously unknown for ginseng root rot and could lead to new disease treatment options.

• 한국균학회지
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• 제8권1호
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• pp.53-57
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• 1980

An undescribed black root rot of soybean, caused by Cylindrocladium crotalariae, was observed in Suweon area. The diseased plants showed yellowing at the top and dry rot at the root. Lesions of roots and stems in the soil were red to brown and main roots were cracked. Although not observed the disease in the field, leaves of inoculated test plants in the greenhouse exhibited circular, brown lesion surrounded by chloratic halos. The fungus was recovered in culture from the infected stem and root, and the perithecia of Calonectria crotalariae were demonstrated to be present as well as the cylindrocladium state. The fungus was pathogenic to the root, stem, petioles and leaves of soybean. The probable source of primary inoculum was microsclerotia formed in infected soybean root and stem from the previous season's soybean debris. Black root rot by this fungus was considered to be one of detrimental factors to the maximum yield of soybean. From the morphological and physiological characteristics and pathogenic behaviors, this fungus was identified as Cylindrocladium(Calonectria) crotalariae.