인삼 뿌리썩음병균(Cylindrocarpon destructans)과 뿌리혹선충(Meloidogyne spp.)은 국내 인삼(panax ginseng C. A. Meyer) 연작장해의 주요인으로, 인삼 생산성 향상을 위해 방제가 필요하다. 본 연구는 새로 개발한 액제 훈증성 토양 소독제를 살포하며 동시에 비닐피복이 가능한 트랙터부착형 토양 소독기를 이용하여 dimethyl disulfide (DMDS)를 처리하였을 때, C. destructans와 뿌리혹선충의 방제효과를 분석하고, 시작기의 성능을 확인하기 위해 수행하였다. 토양 소독기를 이용하여 인삼 재배 포장에 DMDS를 처리한 후 비닐이 피복된 상태에서 5주간 훈증하였다. 토양 소독기의 성능은 약제 살포량 오차 2.5%, 작업능률 0.9h/10a로 40%의 노력절감 효과가 있는 것으로 나타났다. 또한, 처리 전후 C. destructans 의 밀도를 분석한결과 82.5%의 밀도 억제 효과가 있는 것으로 나타났으며, 뿌리혹선충 방제효과는 100%로 나타났다. 따라서, 본 토양 소독기 시작기를 이용하여 능률적으로 DMDS를 처리할 수 있으며, C. destructans와 뿌리혹선충의 방제효과를 볼 수 있는 것으로 판단된다.

토양에 첨가한 8종의 Oil cake 중 Margosa, Undi, Karanj cake은 생강뿌리썩음병의 발생을 억제하였다. 생강수량의 증진효과는 Karanj, Roselle, Mustard cake의 순으로 높았다.

The infection rate of soybean black root rot disease caused by Calonectria crotalariae was about . The isolated fungi from the infected soybean roots and stems were Calonectria crotalariae, Fusarium solani, F. roseum, Phomopsis sojae, Pythium aphanidermatum, Rhizoctonia solani and Macrophomina sp. Among them, C. crotalariae was the most virulent pathogen under the laboratory conditions. Mycelial growth and microsclerotial formation were good on PSA containing 1000cc of water, 100g of potato and 20g of sugar. Mycelial growth, sporulation and microsclerotial formation were good on sterilized root. Perithecial formation was better in the dark condition than in the light. Survival of macroconidia was not available between soil water content. Microsclerotia and mycelium in infected plant debris were survived for 4 months at to soil water content. The plant height, when inoculated with inoculum density, reached approximately half of uninoculated plants. Disease severity was much higher at nonsterilized soil than completely sterilized soil. It was determined that the host range of this pathogen includes soybean, peanut, green bean and red bean.

Ginseng (Pnanx ginseng C. A. Meyer) is famous worldwide, and is very important cash crop and medicinal herb in Korea. It takes four to five years to produce harvestable ginseng roots, and ginseng is attacked by several pathogens during cultivation. We investigated the disease rate caused by ginseng root rot from 6 years old ginseng cultivation fields (Chungnam; 9 fields, Chungbuk; 11 fields, Gangwon 5 fields). The highest disease severity was Dangjin D (2.9) and the lowest one was Gaesan C (0.6). Of the 625 isolations, 340 isolations were classified as Ilyonectria radicicola and Fusarium solani. Finally, genetic diversity of I. radicicola and F. solani was confirmed by sequence analysis. Among the I. radicicola group, I. mors-panacis, which is known as highly virulent pathogen, and I. liriodendri, I. robusta and I. cyclamicicola, which are weakly virulent pathogens, were identified. In the case of F. solani, it is divided into two groups, but it is necessary to conduct diversity research through genetic analysis and pathogenetic studies using various markers. Based on these results, it could be used as a basic data for control of ginseng root rot pathogens.

Background: Some phenolics detected in the soil may inhibit the seed germination and seedling growth of ginseng (Panax ginseng). This study investigated the effect of irrigation and ginseng root residue addition on the soil microbial community and root rot disease in 2-year-old ginseng. Methods and Results: Each 20 ℓ pot was filled with soil infected with ginseng root rot pathogens, and irrigated daily with 2 ℓ of water for one month. After the irrigation treatment, ginseng fine root powder was mixed with the irrigated soil at a rate of 20 g per pot. In descending order, NO3 −, electric conductivity (EC), exchangeable Na (Ex. Na) and K (Ex. K) decreased due to irrigation. In descending order, NO3 −, EC, Ex. K, and available P2O5 increased with the additon of ginseng powder to the soil. The abundance of Trichoderma crassum decreased with irrigation, but increased again with the incorporation of ginseng powder. The abundance of Haematonectria haematococca increased with irrigation, but decreased with the incorporation of ginseng powder. The abundance of Cylindrocarpon spp. and Fusarium spp., which cause ginseng root rot, increased with the incorporation of ginseng powder. The abundance of Arthrobacter oryzae and Streptomyces lavendulae increased with irrigation. The abundance of Streptomyces lavendulae decreased, and that of Arthrobacter spp. increased, with the incorporation of ginseng powder. Aerial growth of ginseng was promoted by irrigation, and ginseng root rot increased with the incorporation of ginseng powder. Conclusions: Ginseng root residues in the soil affected soil nutrients and microorganisms, and promoted ginseng root rot, but did not affect the aerial growth of ginseng.

Background : The causative organism of Astragalus membranaceus (Hwanggi) root rot disease was known as Pythophthora drechsleri. In this study, a new species of root rot causative organism has been identified and reported. Methods and Results : Hwanggi, which has root rot disease, was collected in Jungsun-gun, Gangwon-do. The diseased root was cut into 1 ㎝ size and disinfected with 1% sodium hypochlorite solution for 1 minute and washed with sterile distilled water. The dried samples were dipped in the PDA medium and cultured in at 25℃ incubator. The 21 isolates were cultured under the same conditions and genomic DNA was extracted. The genomic DNA of isolated strains was extracted using a kit of Biofact. The isolated strains were identified using internal transcribed spacer (ITS) region sequencing. The ITS region was amplied using the primer pair ITS1 (5’-TCCGTAGGTGAACCTGCGG-3’) and ITS4 (5’-TCCTCCGCTTATTGATATGC-3’). The PCR was performed in a final volume of 50 ㎕ containing 10 mM Tris-HCl (pH 8.3), 50 mM KCl, 1.5 mM MgCl2, each dNTP at a concentration of 0.2 mM, 1.25 IU of Taq polymerase, each primer at a concentration of 10 pmol, and 2ul of the DNA template. Sequencing was performed by asking Macrogen. The analyzed sequences were compared using the Blast program provided by NCBI. As a result of identification of 21 strains, 13 Fusarium spp., 1 Peronospora sp. (causative organism of downy mildew), 3 Acremonium spp., 3 Uncultured fungus, 1 Phyrtophthora sp.. The main pathogen of wilt disease was known as Fusarium sp., a soil-borne pathogen. After analyzing the systematic taxonomic relationships, the systematic diagram was created using the neighbor-joining method. Conclusion : We have finally identified Phytophthora cryptogea as a causative organism of Hwanggi root rot disease and will check whether the disease has occurred on the inoculation through pot test.

Background : Development of new real-time PCR diagnosis method for simultaneous diagnosis of Cylindrocarpon destructans and Fusarium solani, causative fungi of ginseng root rot disease. C. destructans and F. solani are known to be the major pathogens of ginseng root rot disease. Root rot caused by these pathogens is a disease that is difficult to control because the disease progresses slowly and it is difficult to diagnose early and even when symptoms of plant seeding are present, the disease is already spread in the roots. Diagnostic methods to detect the presence or absence of ginseng roots rot fungi in soil before ginseng cultivation are currently being used as a method for controlling. However, commercialized soil extraction kits and PCR diagnostics have cost, diagnostic time, and single diagnostic problems, and need to develop new diagnostic methods. Methods and Results : Primers and probes in the beta-tubulin 2 gene were designed for species-specific detection. In silico analysis, the detection rate of C. destructans was 100% and the detection rate of F. solani was 95%. The multiplex real time PCR optimization conditions including the internal control were established. The analytical sensitivity using positive samples was 10 copies/㎕ for C. destructans and 10 copies/㎕ for F. solani. As a result of performance comparison test with conventional PCR diagnosis methods, it was confirmed that the developed multiplex real time PCR method has the same or better performance in terms of sensitivity. In the developed soil extraction kit, the extraction time was reduced and the extracted DNA quality was improved, compared to the used soil extraction kit. Conclusion : From the above results, we expect that the developed C. destructans / F. solani multiplex real time PCR diagnosis method and soil extraction kit will be useful for real-time monitoring of ginseng root rot pathogenic fungi in the soil of ginseng cultivation area and diagnosis of suitability of ginseng cultivation area.

Background : Root rot is a major factors of replanting failure in ginseng cultivation. Some of the phenolics detected in the soil could inhibit the seed germination and seedling growth of ginseng. Methods and Results : Water of 2 ℓ was irrigated per pot (20 ℓ) into the soil infected with ginseng root rot pathogens for one month every day. After the irrigation treatment, the powder of ginseng fine root of 20 g per pot was mixed with the irrigated soil. NO3 -, electric conductivity (EC), exchangeable Na (Ex. Na) and K (Ex. K) were decreased in descending order by irrigation. NO3 -, EC, Ex. K, and available P2O5 were increased in descending order by incorporation of ginseng powder into soil. Trichoderma crassum was decreased by irrigation, but it was increased again by incorporation of powder. Haematonectria haematococca was increased by irrigation, but it was decreased by incorporation of powder. Cylindrocarpon spp. and Fusarium spp. causing ginseng root rot were increased by incorporation of powder. Arthrobacter oryzae and Streptomyces lavendulae were increased by irrigation. Streptomyces lavendulae was decreased, and Arthrobacter spp. was increased by incorporation of powder. Aerial growth of ginseng was promoted by irrigation, and ginseng root rot was increased by incorporation of powder. Conclusion : The residues of ginseng root in the soil affected soil nutrients and microorganisms, and promoted ginseng root rot, but did not affect the aerial growth of ginseng.

Background : When the Platycodon grandiflorum is applied before the rainy season, the increase of the incidence of the Platycodon grandiflorum root rot disease increases greatly. This experiment was carried out to reduce the incidence of rot root rot disease through the lodging protecting method. Methods and Results : Three-years-old Platycodon grandiflorum was subjected to four treatments with no treatment, net installation, cutting stem, and removing bud. No treatment was used as a control, and as a further control, netting was used in the Platycodon grandiflorum to set up a treatment with almost no lodging. In the case of cutting stem, the stem was cut off in the middle of June, leaving more than 60 ㎝ before flowering. In the case of removing bud, blooming just before, the bud was removed. As a result, the coverage rate was the highest at 36.9% in the non - treatment area in the middle of July after the rainy season and 0.4% in the net installation. Compared with the case of cutting a lot of stems, 12.7% of the stem was covered with stones, whereas the stalk was 31.8%, which was close to the untreated stomach. As a result of the change of morbidity rate per treatment, it showed a morbidity rate of 49.7% in case of net installation, compared with 60% or more morbidity rate in case of untreated. Conclusion : As a result, an anti-lodging technic has helped prevent the onset of root rot disease. Further research on how to prevent the lodging of Platycodon grandiflorum using cutting stem will be needed.

Background : The soil-borne ascomycete fungus Ilyonectria rdicicola species complex is commonly associated with root rot disease symptoms in ginsneg. Its virulence has been attributed, among other factors, to the activity of hydrolytic cell wall-degrading enzymes (CWDE). Methods and Results : To establish a rapid and accurate detection of Ilyonectria rdicicola, a species-specific primer was developed based on the putative genes of cell wall–degrading enzyme (pectinase, polygalactose, xylanase, xylosidase). Species-specific primer based on the DNA sequences of gene amplified about 200 - 300 bp polymerase chain reaction (PCR) product for Ilyonectria mors-panacis. Conclusion : The primer pair yielded the predicted PCR product size exactly in testing with target pathogen DNAs, but not from the other species of Ilyonectria and species of other phytopathogenic fungi. The primer pair also showed only the species-specific amplification curve on realtime PCR on target pathogen DNA. The detection sensitivity of real time PCR using species-specific primer pair was 10 to 100 times higher than conventional PCR, with 1 to 10 pg/㎕. The approach outlined here could be further utilized as a rapid and reliable tool for the diagnosis and monitoring of the root rot of ginseng.

Background : Ginseng root rot is a devastating disease caused by the fungus, Ilyonectria mors-panacis that generally attacks younger roots (-2 years), leading to defects in root quality, ginsenoside accumulation and also life cycle of the plant. Hence, there is an indispensable need to develop strategies resulting in tolerance against ginseng root rot. The protective role of silicon during pathogen infestation is well documented in other plant systems and a previous study demonstrated that silica nanoparticles are absorbed and accumulated more than the bulk silica in maize. However, the role of silica in ginseng-root rot pathosystem is unknown. Methods and Results : In the present study, we evaluated the effect of silica nanoparticles (N-SiO2) in Panax ginseng during I. mors-panacis infection. Long term analysis (30 dpi) revealed a striking 50% reduction in disease severity index upon 1 mM and 2 mM treatment of N-SiO2. However, N-SiO2 did not have any direct antifungal activity against I. mors-panacis. Candidate genes and metabolites based approach revealed jasmonic acid (JA) mediated sterol accumulation and incresed ginsenside biosyntesis as the key transcriptional reprogramming events orchestrated by N-SiO2 during the fungal infection. Conclusion : In a nut shell, N-SiO2 administration induces transcriptional reprogramming in ginseng roots, leading to increased phytosterol and ginsenosides synthesis resulting in enhanced tolerance against I. mors-panacis.

Background : Replant failure of ginseng is caused by soil-born pathogens causing root rot such as Cylindrocarpon destructans and Fusarium solani. Dazomet are widely used as soil fumigant to solve soilborne problems, and the degradation intermediates are toxic to nematodes, fungi, bacteria, insects and weeds. Methods and Results : The effects of cultivation of green manure crop, maize before and after soil fumigation on the control of ginseng root rot disease were compared using soil of field where 6-years-old ginseng was harvested. Fumigant (dazomet) were used for soil fumigation in May and September, respectively. Maize was grown for soil management before and after soil fumigation. Maize cultivation after May fumigation was delayed the sowing day by 15 days, and the fresh and dry weight decreased significantly. Maize cultivation after May fumigation increased pH but decreased EC, NO3, P2O5, and K significantly. Maize cultivation after May fumigation decreased fungi population and ratio of fungi and bacteria. Growth of 2-years-old ginseng was improved and the incidence of ginseng root rot was significantly decreased by maize cultivation after May fumigation. After harvesting 2-years-old ginseng, the population of Cylindrocarpon destructans was not different among treatments, but Fusarium solani showed a significant increase in September fumigation after maize cultivation. Conclusion : Maize cultivation after soil fumigation was effective in inhibiting ginseng root rot by improvement of mineral composition and microorganism in soils.

Background: The application of crop rotation systems may reduce the occurrence of soil-borne diseases by releasing allelochemicals and by subsequent microbial decomposition. Methods and Results: For reduction of ginseng root rot by the crop rotation system, after harvesting 6-year-old ginseng, fresh ginseng was grown along with continuous cultivation of sweet potato, peanut, and bellflower. Growth of 2-year-old ginseng was significantly inhibited in the continuous cultivation than in the first cultivation. Sweet potato, peanut and bellflower cultivations assisted in obtaining normal yields of ginseng in the first year after the harvest of 6-year-old ginseng. Salt concentration, potassium and sodium contents were gradually decreased, and, organic matter was gradually increased through cirp rotation. Phosphate, calcium and magnesium contents were not altered. The density of the root rot fungus was gradually decreased by the increase in crop rotation; however it was decreased distinctly in the first year compared to the second and third year. The severity of root rot disease tended to decrease gradually by the increase of crop rotation. Conclusions: Short-term crop rotation for three years promoted the growth of ginseng, however root rot infection was not inhibited significantly, although it was somewhat effective in lowering the density of the root rot pathogen.

Background : Korean ginseng is an important cash crop in Asian countries. However, plant yield is reduced by pathogens. Among the Ilyonectria radicicola-species complex, I. mors-panacis is responsible for root-rot and replant failure of ginseng in Asia. It is essential to find a way to reveal the existence of the pathogen before starting cultivation. Therefore, qRT-PCR method is developed to detect and quantify the pathogen in ginseng soils. Methods and Results : In this study, species specific Histone H3 primer set is developed for the quantification of I. mors-panacis. The primer set was applied on DNA of other microbes to evaluate its sensitivity and selectivity on I. mors-panacis DNA. Sterilized soil samples artificially infected by the pathogen in different concentrations were used to evaluate the ability of the primer set to detect the pathogen population in the soil DNA. Finally, the pathogen was quantified in many natural soil samples. The designed primer set was found to be sensitive and selective to I. mors-panacis DNA. In artificially infected sterilized soil samples, the estimated template using qRT-PCR was positively correlated with the pathogen concentration in soil samples (R2=0.94), disease severity index (R2=0.99), and colony forming unit (R2=0.87). In the natural soils, the pathogen was recorded in the most of fields produce bad yields with the range of 5.82 ± 2.35 to 892.34 ± 103.70 pg/g of soil. Conclusion : According to the presented results, the proposed primer set is applicable for estimating soils quality before ginseng cultivation. This will help in the disease management and crop protection in the future.

Background : The fungus Cylindrocarpon destructans (Zins) Scholten is the cause of root rot in many ginseng production areas. Root exudate composition and quantity vary in relation to plant nutritional status, but the impact of the differences on rhizosphere microbial communities is not known. Methods and Results : Five kinds of rotation crops, sudan grass soybean peanut sweet potato, perilla were grown for one year in ginseng garden harvested 6-year-old ginseng. The ratio of gram-negative bacteria, fungi, bacteria, total microbial biomass, aerobic/anaerobic microbes were increased by rotational crop cultivation, while the ratio of actinomycetes and the ratio of saturated to unsaturated fatty acids were decreased. The increase in the fungal density or the increase in the proportion of fungi to the bacteria tended to increase the incidence of root rot, but there was no significant difference. The yield of ginseng root showed a highly significant negative correlation with actinomycetes. The correlation between the soil chemical properties and the incidence of root rot was analyzed by cultivating 23 kinds of green manure crops for one year in field where cultivated ginseng continuously. The survival rate of ginseng showed a highly significant positive correlation with soil acidity and a highly significant negative correlation with nitrate nitrogen, and a significant negative correlation with soil salt concentration. Conclusion : Rotation crops improved soil microbial communities, lowered the rate of fungi and increased the proportion of bacteria, the survival rate of ginseng was significantly correlated with soil acidity, nitrate nitrogen and soil salinity.

Background: Some plants have harmful effects on fungi and bacteria as well as plants. Incorporating into soil as green manures are effective in reducing population densities of soil pathogens. Methods and Results: Twenty-three species of green manure crops were cultivated after the harvest of 6-year-old ginseng and then incorporated green manure into the soil at the flowering stage. The following year, the root rot ratio of 2-year-old ginseng and soil chemical properties were investigated. Sorghum sudanense, Helianthus annuus, and Helianthus tuberosus were relatively high in dry matter production. Without incorporating green manure into soil, NO3, EC (electric conductivity) and K were decreased by 95%, 79% and 65%, respectively. When green manure was incorporated to soil, P2O5 and NO3, were reduced by 41% and 25%, respectively. The survived root ratio of 2-year-old ginseng were significantly increased by 56.2%, 47.5%, and 47.3% in Sorghum sudanense, Ricinus communis and Helianthus tuberosus, respectively, In addition, there was a significant increase in Secale cereale, Chrysanthemum morifolium, Atractylodes macrocephala, and Smallanthus sonchifolius. The survived root ratio of ginseng showed a significant positive correlation with soil pH and a negative correlation with NO3, and EC. Conclusion: Cultivation of Chrysanthemum family mainly using rhizome and root as green manure was effective for root rot disease of ginseng.

Background: Some plants have harmful effects on fungi and bacteria as well as other plants. Incorporating such plant into soil as green manure is effective in reducing population densities of soil pathogens. Methods and Results: Twenty-three species of green manure crops were cultivated after the harvest of 6-year-old ginseng and then incorporated into the soil at the flowering stage. The following year, the root rot ratio of 2-year-old ginseng and soil chemical properties were investigated. In the absence of green manure addition, the NO3 content, electric conductivity (EC), and K content decreased by 95%, 79% and 65%, respectively. In the presence of green manure addition, P2O5 and NO3 contents reduced by 41% and 25%, respectively. The “survived root ratio” of 2-year-old ginseng significantly increased by 56.2%, 47.5%, and 47.3%, in the Sorghum sudanense, Ricinus communis and Helianthus tuberosus treatment, respectively. In addition, there was a significant increase in the “survived root ratio” in the Secale cereale, Chrysanthemum morifolium, Atractylodes macrocephala, and Smallanthus sonchifolius treatments. The “survived root ratio” of ginseng showed a significant positive correlation with the soil pH and a negative correlation with the NO3 contents, and EC. Conclusions: Cultivation of plant form the Chrysanthemum family as green manure, using mainly the rhizomes was effective for the control of root rot disease of ginseng.

Background : Ginseng widely cultivated as a major medicinal herb in Korea, is economically important crop for farmer. Ginseng root disease caused by soil borne pathogens is main factors restricting the quantity and quality of ginseng. The disease can result in harvest loss of up to 20~70% and limits the replanting of ginseng under same field for long time. The traditional control method of agrochemical use is not recommend to control soil borne disease because of difficulty in use and unstable effect. The objective of this study was to evaluate the efficacy of several antagonistic microbes for developing biological control method of ginseng root rot. Methods and Results : To select biocontrol agents against ginseng soil borne disease, several bacteria were isolated from ginseng root and rhizosphere soil evaluated in vitro screening of antifungal bacterial against ginseng root pathogens. Two antagonistic bacteria, ES17 and CJ4, showed the strongest inhibition effect against ginseng root pathogen. In the pot experiment under greenhouse conditions, ginseng seedling dipped in bacterial suspension at inoculum density of 106 cfu/ml for 1 hour were planted in pot containing inoculum. Control effect was examined depend on disease severity index at 30 days after inoculation. Ginseng root treated with CJ4 and ES17 isolate reduced root rot disease development on the ginseng root with degrees of control efficacy of 85% and 70%, respectively. Conclusion : Two biocontrol agent, Burkholderia ambifaria CJ4 and Paenibacillus strain ES17, had strong antifungal efficacy against ginseng soil borne pathogens. These results obtained from in vitro test and pot experiment suggest the potential applicability of the biocontrol agent to control ginseng root rot caused by various soil borne pathogens.