• Korean Journal of Medicinal Crop Science
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• v.23 no.3
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• pp.223-230
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• 2015

To study the effect of crop rotation on the control of ginseng root rot, growth characteristics and root rot ratio of 2-year-old ginseng was investigated after the crops of 18 species were cultured for one year in soil contaminated by the pathogen of root rot. Fusarium solani and Cylindrocarpon destructans were detected by 53.2% and 37.7%, respectively, from infected root of 4-year-old ginseng cultivated in soil occurring the injury by continuous cropping. Content of $NO_3$, Na, and $P_2O_5$ were distinctly changed, while content of pH, Ca, and Mg were slightly changed when whole plant of crops cultured for one year were buried in the ground. All of EC, $NO_3$, $P_2O_5$, and K were distinctly increased in soil cultured sudangrass, peanut, soybean, sunnhemp, and pepper. All of EC, $NO_3$, $P_2O_5$, and K among inorganic component showed negative effect on the growth of ginseng when they were excessively applied on soil. The growth of ginseng was promoted in soil cultivated perilla, sweet potato, sudangrass, and welsh onion, while suppressed in Hwanggi (Astragalus mongholicus), Deodeok (Codonopsis lanceolata) Doraji (Platycodon grandiflorum), Gamcho (Glycyrrhiza uralensis), Soybean. All of chicory, lettuce, radish, sunnhemp, and welsh onion had effective on the inhibition of ginseng root rot, while legume such as soybean, Hwanggi, Gamcho, peanut promoted the incidence of root rot. Though there were no significant correlation, $NO_3$ showed positive correlation, and Na showed negative correlation with the incidence of root rot.

• Research in Plant Disease
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• v.28 no.1
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• pp.19-25
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• 2022

Ginseng is an important medicinal plant cultivated in East Asia for thousands of years. It is typically cultivated in the same field for 4 to 6 years and is exposed to a variety of pathogens. Among them, ginseng root rot is the main reason that leads to the most severe losses. In this study, endophytic bacteria were isolated from healthy ginseng, and endophytes with antagonistic effect against ginseng root rot pathogens were screened out. Among the 17 strains, three carried antagonistic effect, and were resistant to radicicol that is a mycotoxin produced by ginseng root rot pathogens. Finally, Bacillus velezensis CH-15 was selected due to excellent antagonistic effect and radicicol resistance. When CH-15 was inoculated on ginseng root, it not only inhibited the mycelial growth of the pathogen, but also inhibited the progression of disease. CH-15 also carried biosynthetic genes for bacillomycin D, iturin A, bacilysin, and surfactin. In addition, CH-15 culture filtrate significantly inhibited the growth and conidial germination of pathogens. This study shows that endophytic bacterium CH-15 had antagonistic effect on ginseng root rot pathogens and inhibited the progression of ginseng root rot. We expected that this strain can be a microbial agent to suppress ginseng root rot.

• The Korean Journal of Mycology
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• v.47 no.4
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• pp.407-416
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• 2019

A common post-harvest disease of sweetpotato tuber is root rot caused by Fusarium solani in Korea as well as the other countries. Storage root rot disease was monitored earlier on sweetpotato (Ipomoea batatas) in storehouses of different locations in Korea. In the present study, an isolate SPL16124 was choosen and collected from Sweetpotato Research Lab., Bioenergy Crop Research Institute, NICS, Muan, Korea, and confirmed the identification as Fusarium solani by conidial and molecular phylogenetic analysis (internal transcribed spacer ITS and translation elongation factor EF 1-α gene sequences). The isolate was cultured on potato dextrose agar, and conidiation was induced. The fungus was screened for Fusarium root rot on tuber of 14 different varieties. Among the tested variety, Yenjami, Singeonmi, Daeyumi, and Sinjami showed resistant to root rot disease. Additionally, the pathogen was tested for pathogenicity on stalks of these varieties. No symptom was observed on the stalk, and it was confirmed that the disease is tissue specific.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.70-78
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• 2013

Rhizoctonia solani and Fusarium oxysporum cause yield losses in numerous economically important crops. To develop a bio-control agent, cell free extracellular compounds (ECs) of 5 bacterial strains Burkholdria sp. L1, Pseudomonas sp. L4, Pseudomonas chlororaphis VN391, Bacillus subtilis VN21 and Enterobacter sp. VN99 from Vietnamese fields, which reduced levels of R. solani root rot in lettuces and F. oxysporum root rot in tomatoes, were investigated. In a growth chamber, ECs of all antagonists markedly enhanced the biomass of lettuces (10 to 14.1%) and tomatoes (11.38 to 13.88%). In greenhouses, the disease's severity on both crops treated with ECs of the antagonists was reduced significantly and biomass losses in the plants decreased markedly. The reduction level of R. solani root rot in lettuces was 75, 66.7, 50, and 16.7% by ECs of strains L1, L4, VN21 and VN391, respectively. The biomass of lettuces increased markedly by 29.13%, 21.67%, and 23.4% by ECs of strains L1, L4 and VN21, respectively. Similarly, the reduction levels of F. oxysporum root rot in tomatoes was 76.3, 75, 41.7 and 25% by ECs of strain L1, L4, VN21 and VN391, respectively, and the biomass was significantly enhanced by 14.42, 12.7 and 13%, respectively. The ECs of strain L1 exhibited the most effective bio-control agents to suppress R. solani and F. oxysporum.

• Journal of Ginseng Research
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• v.45 no.1
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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.

• The Plant Pathology Journal
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• v.38 no.3
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• pp.212-219
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• 2022

Fusarium root rot caused by the soil-borne fungus Fusarium solani is one of the most important fungal diseases of cassava in Thailand, resulting in high yield losses of more than 80%. This study aimed to investigate if the exogenous application of salicylic acid formulations (Zacha) can induce resistance in cassava against Fusarium root rot and observe the biochemical changes in induced cassava leaf tissues through synchrotron radiation based on Fourier-transform infrared (SR-FTIR) microspectroscopy. We demonstrated that the application of Zacha11 prototype formulations could induce resistance against Fusarium root rot in cassava. The in vitro experimental results showed that Zacha11 prototype formulations inhibited the growth of F. solani at approximately 34.83%. Furthermore, a significant reduction in the disease severity of Fusarium root rot disease at 60 days after challenge inoculation was observed in cassava plants treated with Zacha11 at a concentration of 500 ppm (9.0%). Population densities of F. solani were determined at 7 days after inoculation. Treatment of the Zacha11 at a concentration of 500 ppm resulted in reduced populations compared with the distilled water control and differences among treatment means at each assay date. Moreover, the SR-FTIR spectral changes of Zacha11-treated epidermal tissues of leaves had higher integral areas of lipids, lignins, and pectins (1,770-1,700/cm), amide I (1,700-1,600/cm), amide II (1,600-1,500/cm), hemicellulose, lignin (1,300-1,200/cm), and cellulose (1,155/cm). Therefore, alteration in defensive carbohydrates, lipids, and proteins contributed to generate barriers against Fusarium invasion in cassava roots, leading to lower the root rot disease severity.

• The Korean Journal of Mycology
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• v.29 no.2
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• pp.127-130
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• 2001

A Pythium species was isolated from roots of Codonopsis pilosula showing wilt symptoms in a field at Yonchon, Kyonggido of Korea from late June to early August in 2000. The Pythium species was identified as Pythium myriotylum Drechsler based on various mycological characteristics. The isolate was strongly pathogenic when inoculated to root of C. pilosula plants in pot. The inoculated plants showed typical symptoms of root rot, resulting in reduced growth of root and consequently wilting of above ground part of plants. Pythium root rot of C. pilosula caused by P. myriotylum has not been reported previously in Korea.

• The Plant Pathology Journal
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• v.27 no.4
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• pp.333-341
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• 2011

Two antifungal bacteria were selected from forest soils during the screening of microorganisms antagonistic to Cylindrocarpon destructans, a cause of ginseng root rot. The antifungal bacteria were identified as Bacillus subtilis (I4) and B. amyloliquefaciens (yD16) based on physiological and cultural characteristics, the Biolog program, and 16S rRNA gene sequencing analyses. Antagonistic activity of both bacterial isolates to C. destructans increased with increasing temperature. More rapid starch hydrolytic activity of the bacteria was seen on starch agar at higher temperatures than at lower temperatures, and in the higher density inoculum treatment than in the lower density inoculum treatment. The bacterial isolates failed to colonize ginseng root the root tissues inoculated with the bacteria alone at an inoculum density of $1{\times}10^6$ cfu/ml, but succeeded in colonizing the root tissues co-inoculated with the bacteria and C. destructans. Scanning electron microscopy showed that the pathogen was damaged by the low-density inoculum treatment with the bacterial isolates as much as by the high-density inoculum treatment. Both bacterial isolates were more effective in reducing root rot when they were treated at a concentration of $1{\times}10^6$ cfu/ml than at $1{\times}10^8$ cfu/ml. Also, only the former treatment induced prominent wound periderm formation, related to structural defense against pathogen infection. The results suggest that the bacterial antagonists may have high potential as biocontrol agents against ginseng root rot at relatively low-inoculum concentrations.

• International Journal of Industrial Entomology and Biomaterials
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• v.16 no.2
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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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• v.40 no.1
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• pp.38-46
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• 2016

Background: Blind and excessive application of fertilizers was found during the cultivation of Panax notoginseng in fields, as well as increase in root rot disease incidence. Methods: Both "3414" application and orthogonal test designs were performed at Shilin county, Yunnan province, China, for NPK (nitrogen, phosphorus, and potassium) and mineral fertilizers, respectively. The data were used to construct the one-, two-, and three-factor quadratic regression models. The effect of fertilizer deficiency on root yield loss was also analyzed to confirm the result predicted by these models. A pot culture experiment was performed to observe the incidence rate of root rot disease and to obtain the best range in which the highest yield of root and saponins could be realized. Results: The best application strategy for NPK fertilizer was $0kg/667m^2$, $17.01kg/667m^2$, and $56.87kg/667m^2$, respectively, which can produce the highest root yield of 1,861.90 g (dried root of 100 plants). For mineral fertilizers, calcium and magnesium fertilizers had a significant and positive effect on root yield and the content of four active saponins, respectively. The severity of root rot disease increased with the increase in soil moisture. The best range of soil moisture varied from 0.56 FC (field capacity of water) to 0.59 FC, when the highest yield of root and saponins could be realized as well as the lower incidence rate of root disease. Conclusion: These results indicate that the amount of nitrogen fertilizer used in these fields is excessive and that of potassium fertilizer is deficient. Higher soil moisture is an important factor that increases the severity of the root rot disease.