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 : Ginseng (Panax ginseng C.A. Meyer) is one of the most important medicinal plants in Korea, but its yields are often reduced by a variety of root pathogens. The root rot of ginseng is a destructive soil-borne disease caused by Cylindrocarpon destructans (teleomorph: Ilyonectria radicicola). Methods and Results : Ilyonectria radicicola and its Cylindrocarpon-like anamorph represent a species complex that is commonly associated with root rot disease symptoms on virulence. During the course of this study, several species could be distinguished from I. radicicola sensu stricto based on morphological and culture characteristics. As results of investigated culture characteristics, optimal temperature for mycelial growth of isolates were 20℃, and colony pattern and color were slightly different on PDA. Isolates of I. radicicola were analyzed for their genetic relatedness based on several genes and microsatellite region. I. radicicola group was divided into two small groups. Conclusion : Therefore, we were able to confirm pathogenicity and genetic difference between the isolates in each of the groups of the pathogen. Among these isolates, 21.5% were classified as highly virulent and 78.5% were weakly virulent. *(Corresponding

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 is a perennial, and damage occurs due to various diseases and pests. As a result, yield decreases and quality deteriorates. In particular, it is impossible to be repeatedly cultivated due to root rot, soil-borne disease. For this, in order to control root rot and repeatedly cultivate ginseng by using soil fumigation from virgin soil, this experiment was conducted. Methods and Results : This experiment was performed in ginseng farm field, Geumsan-gun, Chungnam province. And total area was 3ha. And the experiment was conducted in soil where apple trees had been grown. Apple trees were rooted up in 2006. And soil was fumigated in May 2007. With regard to soil fumigant, soil was treated with Basamid of 40kg/10a. After soil fumigation, 5 ton/10a of cattle manure fermented for 1 year was put in the soil in June, and then the soil was cared for by being plowed and rotary-tilled as occasion. Ginseng seeds were sowed in the soil cared for in October 2007. And 4-year-old ginseng was harvested in 2011. The soil from which ginseng was harvested was fumigated by the same method in May 2012, and then ginseng seeds were sowed in 1.5ha in October 2012 and in 1.5ha in October 2013. In October 2013, 3-year-old and 4-year-old ginseng was harvested. And ginseng growth characteristics and root rot incidence was examined. It was shown that 4-year-old ginseng yield after the fumigation of virgin soil was nearly 2 times as high as that of conventional virgin soil cultivation. And root rot didn't occur. After that time, the soil was fumigated again. And when ginseng was cultivated, 3-year-old and 4-year-old ginseng yield was 650kg and 960kg per 10a. And it was shown that root rot incidence was 1.3% and 15.3% in 3-year-old and 4-year-old ginseng respectively. Conclusion : This study showed the results where ginseng can be cultivated repeatedly if soil was fumigated again after ginseng was harvested following the soil fumigation from virgin soil so as to control the ginseng root rot and cultivate ginseng repeatedly.

Background : Ginseng (Panax ginseng C.A. Meyer) is one of the most important medicinal plants in Korea, but its yields are often reduced by a variety of root pathogens. The root rot of ginseng is a destructive soil-borne disease caused by Cylindrocarpon destructans (teleomorph: Ilyonectria radicicola). To monitor contamination with C. destructans in ginseng harvested in 2015 were sampled from 57 different growing fields. The spore number of C. destructans was quantified by use of a specific primers and selective media (radicicol) in soils of ginseng fields. Methods and Results : The ginseng samples were surface-sterilized and placed on potato dextrose agar plates for 7 day incubation at 20℃. Emerging fungal colonies were counted primarily based on colony and conidia morphology. Further species level identification was confirmed by ITS rDNA sequencing. For quantification of the soil-borne C. destructans, the genomic DNA was extracted from the soil using a NucleoSpin soil kit (MN, Germany). Density of C. destructans was determined by species specific real time PCR (qPCR). The qPCR was completed by running a melting curve analysis. Conclusion : The C. destructans associated with root rot disease of ginseng were detected in more than 60% in pyeongtaek-1, pochenon-1, jecheon-1, chungju-1 and jinan-4. As results of the study, the correlation between pathogen density and identification clearly clarified in the soil.

Background : Ginseng root rot caused by soil-borne pathogens, Cylindrocarpon destructans and Fusarium solani, is a major factors of replanting failure in ginseng cultivation. Some of the phenolic compounds detected in the soil of commercially cultivated American ginseng could inhibit the seed germination and seedling growth of American ginseng. Our study is to investigate the causes of replanting failure of ginseng by overhead flooding treatment and soil incorporation of ginseng fine root in soil infected with root rot pathogens. Methods and Results : To make soil occurring continuous cropping injury, 2-year-old ginseng infected with Cylindrocarpon destructans replanted in soil cultivated ginseng for 5 years. Treatment are as follows: 1) control, 2) water of 2ℓ was irrigate infected soil of 20ℓ, 3) ginseng fine root of 20g was mixed with infected soil of 20ℓ. Soil pH was increased, while other inorganic components were significantly reduced by overhead flooding treatment. Soil incorporation of ginseng fine root decreased soil pH, but increased EC, NO3, P2O5 and K, meanwhile, did not affected changes in organic matter, calcium, magnesium, sodium. Irrigation treatment in soil occurring replanted failure promoted distinctly above-ground growth of ginseng, and inhibited the occurrence of root rot because inorganic nutrient like NO3, P2O5 and K were decreased to optimal levels, and the density of soil pathogens could be reduced. Growth of ginseng was not inhibited, while root rot was promoted by soil incorporation of ginseng fine root. Conclusion : Irrigation treatment was effective in promoting the growth of ginseng and inhibited root rot distinctly. Ginseng fine root remaining in the soil after ginseng harvest did not affect the above-ground growth of ginseng, while promoted the occurrence of root rot.

Fusarium crown root rot (FCRR) is a severe fungal disease caused by Fusarium oxysporum f. sp. radicis-lycopersici (FORL) in tomato. Resistance to FORL is conferred by single dominant locus Frl on chromosome 9, but its precise genomic location is not clearly determined. In this study, detailed location of Frl was assessed by using a set of molecular markers physically anchored on Chr.9 and F2 and RIL population derived from FORL-resistant inbred AV107-4 (S.lycopersicum) x susceptible L3708 (S. pimpinellifolium). Bioassay of the two populations with a FORL strain isolated from Korea resulted in single dominant heritance of the resistance. Two SCAR and 11 CAPS markers encompassing 3.6Mb~72Mb of Chr.9 were developed from the Tomato-EXPEN 2000 map and SolCAP SNP-array analysis. These markers were genotyped on 345 F2 plants. A high level of cosegregation with the resistance were observed for 5 markers which were mapped at a large physical interval of 5.1Mb (T1212) to 46.4Mb (SSR237), indicating that genetic recombination was highly suppressed in this region. Cosegregation of these markers with Frl was confirmed by using 126 RILs. The results implied that, in contrast with the previously reported long arm, Frl is present on a pericentromeric region of short arm of Chr. 9, in which crossing-over is severely suppressed. The marker set was further tested on 12 FORL-resistance or susceptibility commercial cultivars. Unlike the biparental populations, frequent linkage break was observed for T1212 and D4 in commercial cultivars. T1212 and D4 showed 50% and 100% match with the phenotype, respectively. D4, a CAPS, was converted to a high resolution melting (HRM) marker and tested on 55 breeding lines from private seed companies (Fig.3). All breeding lines showed the HRM genotype for resistance allele, indicating that D4 can be useful for selecting FORL-resistance tomato plants.

To study the effect of crop rotation on the control of ginseng root rot, growth characteristics and root rot ratioof 2-year-old ginseng was investigated after the crops of 18 species were cultured for one year in soil contaminated by thepathogen of root rot. Fusarium solani and Cylindrocarpon destructans were detected by 53.2% and 37.7%, respectively, frominfected root of 4-year-old ginseng cultivated in soil occurring the injury by continuous cropping. Content of NO3, Na, andP2O5 were distinctly changed, while content of pH, Ca, and Mg were slightly changed when whole plant of crops cultured forone year were buried in the ground. All of EC, NO3, P2O5, and K were distinctly increased in soil cultured sudangrass, pea-nut, soybean, sunnhemp, and pepper. All of EC, NO3, P2O5, and K among inorganic component showed negative effect onthe growth of ginseng when they were excessively applied on soil. The growth of ginseng was promoted in soil cultivatedperilla, 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, NO3 showedpositive correlation, and Na showed negative correlation with the incidence of root rot.