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: 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 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. After May fumigation, the sowing date of maize was delayed by 15 days and thus its dry weight was 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 the 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 between treatment of May and September, but Fusarium solani showed a significant increase in September fumigation after maize cultivation. Conclusions: Maize cultivation after soil fumigation was effective in inhibiting ginseng root rot by the amendment of mineral composition and microorganism in fumigated soil.

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 : This study was conducted to examine the suitability of the blue/white vinyl for ginseng cultivation greenhouses in different regions in an effort to develop a stable ginseng cultivation technology and contribute to popularizing ginseng greenhouse farming. Methods and Results : For comparison purposes, ginseng plants were cultivated in the traditional shading and greenhouse shading facilities. The average temperature in the greenhouse shading facilities during the period of May through October was 20.5℃ in Namwon, 21.4℃ in Jinan, and 23.3℃ in Iksan, with Iksan recording a 1.9–2.8℃ higher average temperature, presumably due to its location in a plain area with low elevation. The average temperatures in the traditional shading facilities ranged between 22.9℃ and 25.7℃, 2.4–2.6℃ higher compared with the greenhouse shading facilities. As for the incidence of disease and pest, as low as 0.1–0.3% of the plants grown under greenhouse shading were infected with Colletotrichum dematium, Alternaria panax, and Rhizoctonia solani, whereas much higher incidences were noted in the control plants, with 3.3–11.3%, 4.7–17.0%, 0.1–0.5%, and 3.0–5.7% infected with Colletotrichum dematium, Alternaria panax, Rhizoctonia solani, and Phytophthora cactorum, respectively, throughout the regions. Heat injury occurred only in Iksan (0.3%) in the case of greenhouse-shaded plants, whereas the control plants suffered from much severer heat injury: 3.5% in Namwon, 10% in Jinan, and as high as 35.3% in Iksan. As for the roots, Namwon outperformed other regions in root length (29.7 ㎝), taproot length (8.7 ㎝), and taproot diameter (25.3 ㎜), and also the root fresh weight (53.4 g), followed by Jinan (48.7 g) and Iksan (40.4 g). In yield as well, the greenhouse in Namwon outperformed other regions with 1,297㎏/10a, followed by Jinan (1,183 ㎏) and Iksan (932 ㎏). The effect of greenhouse blue-white vinyl shading on yield by region was analyzed to increase of 177% in Namwon, 209% in Jinan, and 173% in Iksan with respect to their respective traditional shading facilities. Conclusion : The suitability of the blue/white vinyl shading in ginseng cultivation greenhouses was tested experimentally in three different regions. As a result, greenhouse-shaded ginseng plants were found to be much less affected by heat injury compared with traditionally shaded ginseng plants, resulting in much higher yields in all regions. This allows the conclusion that greenhouse ginseng cultivation can contribute to more stable ginseng yield and popularization of ginseng cultivation.

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.