Background : This study was conducted to investigate the resistance of Collectotrichum gloeosporioides to 9 fungicides. Methods and Results : With 3 isolates of Collectotrichum gloeosporioides obtained from diseased leaf of ginseng, it was conducted to detect the fungicide resistance of C. gloeosporioides against 9 chemicals through an agar dilution method. PDA medium was used for monitoring the resistance. Among the chemicals, fenhexamid・prochloraz manganese complex, fluazinam and metconazole exhibited high antifungal activity to the ginseng anthracnose fungus. When measuring the effectiveness for the prevention of anthracnose, 3 fungicides at 10 ㎍/㎖ showed 88.1 - 94.7% of preventive effect against C. gloeosporioides. But, the isolates resist to dimethomorph・dithianon, iminoctadine tris (albesilate), kasugamyci n・thiophanate-methyl, dimethomorph・pyraclostrobin, azoxystrobin. Conclusion : In summary, to develop the control system with fungicides, 3 fungicides (fenhexamid・prochloraz manganese complex, fluazinam and metconazole) were applied on ginseng at the indicated time. A reduced spray program based on efficacious fungicides will be useful for ginseng growers and provide more options for controlling anthracnose in Korea.

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: A soil-borne pathogenic fungus, Ilyonectria radicicola (Cylindrocarpon destructans) causes root rot on ginseng (Panax ginseng C. A. Meyer) and is known to attack many other plants. The Nectria/Neonectria radicicola complex has been renamed as the I. radicicola complex after analysis of its multi-gene relatedness and morphological characteristics. The fungi in this complex have been reclassified into 16 species under the genus Ilyonectria based on characteristics analysis Methods and Results: To obtain useful data from the Korean ginseng root rot, I. radicicola was isolated from the rhizosphere soils of the chestnut tree. They were identified through a pathogenicity test and a survey of the morphological features. The existence of I. radicicola in soil samples was confirmed by PCR detections using nested PCR with species-specific primer sets. These were subsequenctly isolated on semi-selective media from PCR-positive soils. Genetic analysis of the I. radicicola complex containing these pathogens was done by comparing the DNA sequences of the histone h3 region. These isolates originating from the rhizosphere soils of chestnut constituted a clade with other closely related species or I. radicicola isolates originating from ginseng or other host plants, respectively. Additionally, the pathogenicity tests to analyze the characteristics of these I. radicicola isolates revealed that they caused weakly virulent root rot on ginseng. Conclusions: This is the first study reporting that I. radicicola isolates from chestnut rhizosphere soils can attack ginseng plant in Korea. Thus, these results are expected to provide informations in the selection of suitable fields for ginseng cultivation.

Background : A soil-borne pathogenic fungus, Ilyonectria radicicola (Cylindrocarpon destructans) species complex causing ginseng root rot is the major pathogen on ginseng. DNA extraction from soil is necessary to confirm the presence of ginseng root rot pathogen, I. radicicola. Methods and Results : In order to the increase the detection sensitivity of pathogens present in the soil, the existing soil DNA extraction method was modified to inctease the efficiency of the PCR reaction and to increase the amount of soil samples that can be analyed once by 500 times. For increase the DNA concentration, phenol : chloroform : isoamylalcohol (25 : 24 : 1) were used instead of chloroform : isoamylalcohol (24 : 1), and the sensitivity of PCR was increased by using purification kit. Conclusion : The modified DNA extraction method can detect ginseng root rot pathogen (I. radicicola) with DNA extraction and purification higher than the conventional method.

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 : 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 : 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