• Korean Journal Plant Pathology
• /
• v.12 no.4
• /
• pp.422-427
• /
• 1996

인삼뿌리썩음병균(Cylindrocarpon destructans)후막 포자의 형성은 CD(Czapek`s dox broth)와 SNY(Spezieller Nahrtoffarmer yeast extract broth)배지에서 진탕배양(2$0^{\circ}C$, 120 rpm)하면 양호하였다. 특히 CD배지에서 2$0^{\circ}C$로 30일간 진탕배양하면 5.99 log 후막포자/ml로 형성되었다. 후막포자의 발아율은 12.9~23.3%로 CD배지와 SNY배지에서 좋았으며 발아적온은 5~1$0^{\circ}C$였고, 최적 pH는 6이었다. 그러나 2$0^{\circ}C$이상에서는 전혀 발아하지 않았으며 pH 7.0이상에서는 발아율이 급속히 저하되었다. 인삼추출물 3%, GA 10 ppm, IAA 10 ppm, NOVOZYM\ulcorner234 20 ppm을 처리 할 경우 대조구에 비해 발아율이 증가하였다. 특히 NOVOZYM\ulcorner234 20 ppm 처리구는 발아율이 무처리에 비해 2배 증가하였다. CD배지(pH5)에 NOVOZYM\ulcorner234 20 ppm과 GA 10 ppm을 조합처리하고 5$^{\circ}C$로 정치배양 할 때 후막포자의 발아율은 49.4%로 가장 높았다.

• The Korean Journal of Mycology
• /
• v.29 no.2
• /
• pp.127-130
• /
• 2001

A Pythium species was isolated from roots of Codonopsis pilosula showing wilt symptoms in a field at Yonchon, Kyonggido of Korea from late June to early August in 2000. The Pythium species was identified as Pythium myriotylum Drechsler based on various mycological characteristics. The isolate was strongly pathogenic when inoculated to root of C. pilosula plants in pot. The inoculated plants showed typical symptoms of root rot, resulting in reduced growth of root and consequently wilting of above ground part of plants. Pythium root rot of C. pilosula caused by P. myriotylum has not been reported previously in Korea.

• The Korean Journal of Pesticide Science
• /
• v.18 no.4
• /
• pp.396-403
• /
• 2014

Ginseng (Panax ginseng C. A. Meyer) is an economically valuable pharmaceutical crop in Korea. In order to find promising biocontrol agents for soil-borne fungal pathogens which infect ginseng roots, we have isolated actinomycete, BK185 from soil. The isolate was investigated for the antifungal activity against to ginseng rot pathogens prior to testing genetic and chemical properties. The strain was identified as Streptomyces sp. using phylogenetic analysis based on 16S rRNA gene sequence. The most closely related species was S. sporoclivatus and S. geldanamycininus with high similarities (>99%). The isolate, BK185 showed positive reaction for PCR detection targeting biosynthetic gene clusters of PKS (Type-I polyketide synthase) and NRPS (Non-ribosomal polypeptide synthetase) genes. Major metabolite from the BK185 was analyzed by The LC/MS and identified to geldamycin, which was known to contained broad antibacterial, antifungal or anticancer activities. The results provide evidences that the strain, BK185 can be promising biocontrol agent for ginseng organic farming.

• Research in Plant Disease
• /
• v.7 no.1
• /
• pp.20-24
• /
• 2001

As stand-missing rate (SMR) of ginseng plants in fields are directly related to the ginseng root rot, the forecasting model for the root rot progress in ginseng fields was developed, using the estimated SMRs by disease incidence (DI) of ginseng seedling in the soil-indexing bioassay and the estimate of DI derived from soil environmental factors or rhizoplane microflora. For fitness analysis of the forecasting model, simple correlation and linear regression between SMRs at different planting ages in fields and their estimates by 3 factors of the model were evaluated.The SMR estimated from the factor of DI in the bioassay had much higher fitness to the SMR observed in fields than that from the factors of soil environments and rhizoplane microflora. The estimated SMRs in young and aged ginseng fields by DI in the bioassay were significantly correlated with the observed SMRs in 3- and 5-year-old ginseng fields, respectively (p=0.01). this implicates that indexing preplanting field soils with the forecasting model using DI in the bioassay can provide an information to determine the suitability of the fields for ginseng cultivation, and that indexing cultivating field soils can be helpful to determine the time of harvesting to reduce further yield loss by root rot in continuous cultivation in the next year.

• Journal of Korean Society of Forest Science
• /
• v.95 no.4
• /
• pp.388-392
• /
• 2006

To investigate physiological characteristics and genetic diversity of Rhizina undulata isolates distributed in Korea, cultural characteristics and random amplified polymorphic DNA (RAPD) of 13 Rhizina undulata isolates from Pinus densiflora and P. thunbergi stands were analyzed. There were no correlations between the host species of R. undulata isolates and the mycelial growth of R. undulata isolates on culture media supplemented with water-soluble extract from the two different host species, i.e., Pinus densiflora and P. thunbergi. Genetic diversity of genomic DNA from 13 R. undulata isolates was analyzed by RAPD using 12 random primers. There was no differentiation in RAPD profiles among the isolates from Korea. But, there was some differentiation in RAPD profiles between Korean isolates and Japanese isolates, with 88% homology by phylogenetic tree analysis.

• The Korean Journal of Pesticide Science
• /
• v.11 no.1
• /
• pp.18-26
• /
• 2007

Fungicidal screening was performed to control soybean black root rot caused by Calonectria ilicicola through in vitro and greenhouse assays. In in vitro assay, 25 fungicides were assessed by an agar dilution method and a 96-well microtiter plate method. While protective fungicides including dithianon, dichlofluanid, mancozeb, and captan showed a very low activity against the mycelial growth C. ilicicola SC03-15 in the agar dilution method, they displayed potent inhibitory activity against spore germination in a 96-well microtiter plate method with $EC_{50}$ values of 4.65, 0.61, 4.64, and $0.29{\mu}g\;mL^{-1}$, respectively. Ergosterol biosynthesis-inhibiting (EBI) fungicides showed different antifungal activity against mycelial growth and spore germination according to molecules. Difenconazole displayed higher antifungal activity against spore germination rather than mycelial growth, and prochloraz inhibited potently both mycelial growth and spore germination with EC50 values less than $1.8{\mu}g\;ml^{-1}$. In contrast, the other EBI fungicides inhibited more highly mycelial growth than spore germination. Carbendazim+diethofencarb and dazomet also inhibited both mycelial growth and spore germination of C. ilicicola SC03-15 at very low concentrations. In greenhouse assay, carbendazim+diethofencarb effectively controlled a soybean black root rot by drenching 2 days before or after inoculation. In addition, tebuconazole showed potent curative activity against soybean black root rot.

• Research in Plant Disease
• /
• v.11 no.2
• /
• pp.208-212
• /
• 2005

At the survey of June, 2002, total 294 dead frees were found in 20 ha of Black pine (Pinus thunbergii) forest located in the western coastal region of Korean peninsula. The dead trees were scattered over the 27 place as groups of about ten trees each. As a result of the field survey on the relationship between the conditions of dead trees and the occurrence of fruiting bodies of Rhizina undulata around the dead and/or dying trees, from June 2002 to August 2004 in the four plots, the occurrence of infected trees was observed as a shape of an irregular concentric circle from the first infected tree and R. undulata was found mainly around the dead tree. Because there was no observation of any other insects and pathogens which would kill trees, the cause of tree death in groups was considered owing to R. undulata. From the analysis of the physical and chemical proper ties of the soil collected from the damaged areas, the pH of soil was between 4.6 and 5.8 and the contents of soil nutrients were very low. Any "fire" trace was not found at all the 27 damaged places in the area, Taean, Chungcheongnam-Do, which are generally known as an important factor to initiate development of the disease. Therefore, further examination is needed to verify precisely about other environmental factors related with the group dying of the Black pines in this area beside 'fire'.

• Research in Plant Disease
• /
• v.24 no.4
• /
• pp.332-338
• /
• 2018

In August of 2011, a wilting disease of ginseng was observed at Bongwha, Gyeongbuk province, Korea. Affected plants initially show withering symptoms on leaves of ginseng. As the disease progresses, withering leaves spread downward, eventually encompassing the whole plant. Leaves lose vigor but remain pale green. Symptoms of roots were brown, and soft rots characterized by moist and watery decay of the whole ginseng root, which initiated as small brown, water-soaked lesions of hairy roots and enlarged to the entire roots. The causal organism isolated from the infected roots was identified as Serratia plymuthica based on its physiological and biochemical characteristics, by cellular fatty acid composition (GC-FAME), the utilization of carbon sources (BioLog System), and 16S rRNA sequence of the isolated bacterium were 99% homologous to those of Serratia plymuthica strains. Artificial inoculation of the bacterium produced the same brown or soft rot symptoms on the ginseng roots, from which the same bacterium was isolated. This is the first report of bacterial root rot caused by the Serratia plymuthica in ginseng in Korea. Serratia plymuthica has been used as antagonistic microorganism for biological control on several crop plants. But it was proved pathogen of ginseng at humid condition in this study.

• 한국약용작물학회:학술대회논문집
• /
• 2008.11a
• /
• pp.173-174
• /
• 2008

• 한국약용작물학회:학술대회논문집
• /
• 2011.04a
• /
• pp.110-111
• /
• 2011