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 : This study was carried out to distribute superior cultivars to farmers by analyzing growth characteristics of ginseng and effectively set the target for breeding by investigating annual agronomic characteristics of ginseng. Methods and Results : As a plant materials, Chunpoong (CP), Yunpoong (YP), Gopoong(GP), Gumpoong (GU) and Sunun (SU) were transplanted in Eumseong (ES), Geumsan (GS) and Yeoncheon (YC) on March 2013. Cultivation and management were conducted on the basis of the standard guidelines. According to stem and petiole by region, YC represent the largest stem diameter, leaf length and petiole length of cultivars, followed by those in ES and those in GS. Leaf growth of cultivars was overall the best in YC. Although CP had long and narrow leaves in all regions, YP and SU had short and narrow leaves. Root weight of all cultivars was the best in YC, but there was no significant differences by them. Growth of CP, YP and GP was generally good in ES. Growth of cultivars was relatively even in GS, but it was poor compared to cultivars which were cultivated in ES and YC. Conclusion : There were considerable differences in root growth of cultivars. However, this results suggest that CP of 4-year-old is produced stably in some regions because it had a small coefficient of variation.

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.