• Journal of Ginseng Research
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• v.13 no.1
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• pp.114-118
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• 1989

Tolclofos-methyl applied as seed dipping at 1,000 ppm for 3 hrs before sowing and soil drenching at the rate of 300 g ai./10 a in the middle of April protected emerging seedlings of Panax ginseng from damping-off caused by Rhiiutonia solani(AG2-1) in Yangjik Soil artificially infested with the pathogen. Germination rates with tolclofos-methyl, pencycuron, and control were 53.7%, 45.8%, and 7.5%, respectively, while the rate of the seeds at non-infested soil was 62.6%. The effectiveness of Tolclofos-methyl against the pathogen in the soil lasted upto 32 days in vitro. However, the transpiratio of ginseng seedlings increased greatly with chemical treatment, showing 0.02, 0.12, and 0.24 m1/cm2 leaf area/day at 0, 1,2, and 4 ppm a.i. of the fungicide, respectively.

• Journal of Ginseng Research
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• v.14 no.3
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• pp.432-436
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• 1990

Incidence of damping-off callsed by Rhizoctonia solani was 0.6-10.9% at "Yangjik" seedbed in Pocheon, Korea. The seedbeds where the lengths of etiolated stems (underground portion) of ginseng seedlings were 0.78-1.25 cm showed 0.8-3.2% of the disease, while 6.9-10.9% disease incidence was observed at the seedbeds with the longer etiolated stem (1.89-2.26 cm). The pathogen produced a typical girdle symptom on the etiolated portion of ginseng stems close to the soil surface. The deeper the seeds were sown, the more the disease occurred in pot soil inoculated with the pathogen, AG 2-1, showing 18.4, 27.4 and 32.9% of damping-off at the seeding depth of 1, 2 and 4 cm, respectively. Cuticle layers of colored stems (over ground portion) were well - developed to be 42.8, 58.0, and 55.0 um in thickness compared to the etiolated stems with 8.5, 15.0 and 8.0um for seedling, 2 year-old, and 3 year-old ginsengs, respectively, when the disease occurred. In the seedling and 2 year-old ginseng, the colored stems were more rigid than the etiolated. There was however, no difference in rigidness of the stem of the 3 year-old ginseng where the disease is not severe as in seedlings and 2 year-old ginseng plants.ng plants.

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.176-181
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• 2010

Brown patch (Rhizoctonia solani AG1-1), dollar spot (Sclerotinia homoeocarpa), pythium blight (Pythium spp.), anthracnose (Colletotrichum graminicola), yellow patch (Rhizoctonia cerealis) and Zoysia patch (Rhizoctonia solani AG2-2) are the major turfgrasses diseases in Korea. In this study, 23 medicinal plant extracts were tested for antifungal activities against turfgrass pathogenic fungi. In paper disk diffusion method, 12 medicinal plant extracts, including Sophora flavescens, showed antifungal activity. Also, in the test of antifungal activity on media contained the extracts of S. flavescens, Curcuma longa, Rheum undulatum, Coptis chinensis and Asiasarum sieboldi showed above 80% inhibitory effects on the mycelial growth in 110 mg/10 ml concentration of the extracts. S. flavescens, in particularly, showed antifungal activity against the six turfgrass pathogenic fungi. The inhibition rate of S. homoeocarpa was 100% in 10 mg/10 ml, 5 mg/10 ml and 2 mg/10 ml concentrations of C. longa extract. In case of Pythium spp., the extracts of S. flavescens, R. undulatum and C. chinensis showed 100 % inhibition rate on the test media.

• Asian Journal of Turfgrass Science
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• v.19 no.2
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• pp.73-83
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• 2005

This study was carried out to investigate control efficacy of fungicides mixed with pyroligneous acid on Large patch caused by Rhizoctonia solani AG2-2. R. solani AG2-2 was not inhibited by concentration of 500 times and 1,000 times diluents of pyroligneous acid. It is thought that R. solani AG2-2 was not inhibited by Pyroligneous acid alone. Pencycuron and tebuconazol mixed with pyroligneous acid had a good effect in prevention of R. solani AG2-2 in zoysiagrass. Concurrently, it was observed that those were reduced $50\%$ of usage of fungicides. 500 times and 1,000 times diluents of pyroligneous acid treated group had a significantly effect compared to control turf in the leaf length, leaf width and dry weight. In conclusion, usage of fungicides could be reduced about $50\%$ by a fungicides mixed with pyroligneous acid for protection of R. solani AG2-2. Therefore, It is thought that fungicides mixed with pyroligneous acids can be reduced an economic load and also an environmental pollution such as a tolerance to pathogenic bacteria and a destruction of an ecological system of soil microbes according to use fungicides.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.124-128
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• 2015

Large patch, caused by Rhizoctonia solani AG2-2 IV, is a soil-born disease that is the most important of warm season turfgrass such as zoysia and Bermuda grass. This study was conducted to analysis of the soil microbial community structure on large patch. Center of the large patch (CLC), edge (CLE) and healthy (CLH) part of microbial communities were examined using metagenomics in Phylum level. Distribution trends of the rhizosphere microorganisms were similar to the order Proteobacteria, Acidobacteria, Chloroflexi, Firmicutes, Planctomycetes, Gemmatimonadetes, Nitrospira, Cyanobactria and Verrucomicrobia in soil collections. Contrastively Actinobacteria was more 56% abundant in healthy part soil (16%) than in the center (9.28%) or edge (10.84%) parts. Taxonomic distributions were compared among the CLC, CLE and CLH, total 6,948 OTUs were detected in the CLC, 6,505 OTUs for the CLE and 5,537 OTUs were detected in the CLE. Distributions of Actinobacteria OTUs were appeared 615 OTUs in the CLC, 709 OTUs in the CLE and 891 OTUs in the CLH. Among Actinobacteria, 382 OTUs were overlapped in the all soils. Not matched OTUs of CLH (286 OTUs) was detected 23 times higher than CLC (91 OTUs) and CLE (126 OTUs).

• Journal of Life Science
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• v.14 no.4
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• pp.689-695
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• 2004

This study was investigate the occurrence of bottom rot caused by Rhizoctonia solani at the crisphead lettuce fields in Uiryeong-gun, Gyeongsangnam-do from November to December in 2003. Incidence of bottom rot on crisphead lettuce was up to 5.3% at the six plastic houses. A total of 30 isolates of R. solani were obtained from diseased leaves of plants and were tested by artificial inoculation to the host. Among them, PY-1 isolate was selected showing highly virulent on the whole plant and was identified as R. solani AG1 (IB) based on the anastomosis test, morphological and cultural characteristics. Symptoms of bottom rot by PY-1 isolate produced small dark brown, depressed and elliptical spots on the lower part of leaves in the early stage as same as at the fields, were enlarged onto the upper part of leaves later, and the infected plant wilted and ultimately died in the end. For the pathogenicity test, triturated mycelia-inoculum (A$_{550}$=1.0) of PY-1 isolate was selected the most effective inoculum showing disease incidence of 51.1% for the mycelial inoculation at pot assay. Otherwise, WSRP media-inoculum (wheat brane ： sawdust ： rice brane ： PDB media=30 g ： 10 g ： 10 g ： 100 ml, w/w/w/v) of PY-1 isolate was effectual inoculum showing disease incidence of 61.6% for soil inoculation at the plastic house. Also, in selection of density and amount of inoculum, most suitable density of triturated mycelia-inoculum and amount of WSRP media- inoculum were determined as $A_{550}$=1.0 and 40 ml, respectively. This is the first report on the pathogenicity test using by WSRP media-inoculum of R. solani PY-1 isolate for the bottom rot of crisphead lettuce.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.70-75
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• 2013

Seven medicinal plant extracts were tested for antifungal activities against six species of the major turfgrass pathogenic fungi (Colletotrichum graminicola, Pythium spp., Rhizoctonia cerealis, Rhizoctonia solani AG1-1, Rhizoctonia solani AG2-2, and Sclerotinia homoeocarpa) using paper disk diffusion method. Three medicinal plant extracts, including Pinus densiflora showed antifungal activities. In suppression of mycelium growth test, on medium adding P. densiflora extract showed that inhibition rate of mycelium growth were above 80% in 10 mg/10 ml concentration of the extract. The inhibition rate of Pythium spp. was 100% and C. graminicola was 84.3% in 10 mg/10 ml concentrations of P. densiflora extract, respectively. In particularly, the inhibition rate of Pythium spp. was 89.5% in 2 mg/10 ml concentrations of P. densiflora extract. As a result, P. densiflora extract showed high antifungal activity to Pythium spp. and C. graminicola of the turfgrass pathogen in in vitro test.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.326-330
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• 2012

Antifungal metabolites were isolated from a culture of Pseudomonas aurantiaca IB5-10. Chemical structures of the metabolites were elucidated as phenazine-1-carboxylic acid (PCA; 1), 2-hydroxyphenazine (2-OH-PHZ; 2), and cyclo-(L-Pro-L-Val; 3), respectively, based on spectroscopic methods. Among them, 3 was isolated for the first time from this strain. The antifungal activities of 1-3 were evaluated against a variety of plant pathogens. To the best of our knowledge, the antifungal activities of 3 against plant fungal pathogens have been evaluated for the first time in this work. PCA (1) showed the most potent antifungal activities against Phytophthora capsici, Rhizoctonia solani AG-1(IA), and Pythium ultimum with MICs (${\mu}g/ml$) of less than 1.0, 1.3, and 2.0, respectively. On the other hand, 2-OH-PHZ (2) showed potent antifungal activity against R. solani AG-1(IA) with the MIC (${\mu}g/ml$) of 2.0, whereas it showed moderate antifungal activity against P. ultimum with the MIC (${\mu}g/ml$) of 50.0. In addition, 3 showed antifungal activity against only R. solani AG-1(IA).

• The Plant Pathology Journal
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• v.32 no.2
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• pp.85-94
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• 2016

Studies were conducted to determine the role of 3-methylthioproprionic acid (MTPA) in the pathogenicity of potato stem canker, Rhizoctonia solani, and the concentrations required to inhibit growth of R. solani under laboratory and plant house-based conditions. The experiments were laid out in a completely randomized design with five treatments and five replications. The treatments were 0, 1, 2, 4, and 8 mM concentrations of MTPA. The purified toxin exhibited maximal activity at pH 2.5 and $30^{\circ}C$. MTPA at 1, 2, 4, and 8 mM levels reduced plant height, chlorophyll content, haulm fresh weight, number of stolons, canopy development, and tuber weight of potato plants, as compared to the control. MTPA significantly affected mycelial growth with 8 mM causing the highest infection. The potato seedlings treated with MTPA concentrations of 1.0-8.0 mM induced necrosis of up to 80% of root system area. Cankers were resulted from the injection of potato seedling stems with 8.0 mM MTPA. The results showed the disappearance of cell membrane, rough mitochondrial and cell walls, change of the shape of chloroplasts, and swollen endoplasmic reticulum. Seventy-six (76) hours after toxin treatment, cell contents were completely broken, cytoplasm dissolved, and more chromatin were seen in the nucleus. The results suggested that high levels of the toxin concentration caused cell membrane and cytoplasm fracture. The integrity of cellular structure was destroyed by the phytotoxin. The concentrations of the phytotoxin were significantly correlated with pathogenicity and caused damage to the cell membrane of potato stem base tissue.

• Journal of Ginseng Research
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• v.28 no.4
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• pp.183-190
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• 2004

On May of 2002, the 34 isolates of Rhizoctonia solani were isolated from the symptom of damping-off on basal stems of 2-year-old to 6-year-old Panax ginseng which were cultivated in the 17 fields in Kyunggi-do, Chun­gcheungnam-do and Jeollabuk-do province in Korea. All isolates were identified as anastomosis group 2-1. Pre-emer­gence damping-off occurred on underground part of stem of 2-year-old ginseng in the pot trial with artificial inoculation. However, in the 4-year-old ginseng field with artificial inoculation, post-emergence damping-off occurred. The severe incidence of damping-off was found in the 6-year-old ginseng field in Kimje-si, Jeollabuk-do province on June 5 of 2003, the rate of which showed $18.6{\%}$ of area in the field by spread of the disease since 2-year-old. The sclerotia of R. solani, started to be formed after 7 days incubation on potato dextrose agar at $25^{\circ}C,$ were grayish brown, spherical to irregular and about $500{\mu}m$ in diameter, which became dark brown after 14 days incubation. The temperature range for the myce­lial growth of R. solani isolates was $5\~30^{\circ}C,$ and the optimal temperature was $25^{\circ}C,$ their growth were very poor at $5\;or\;30^{\circ}C$. The isolates grew at the range of pH $4.5\~8.1$ tested and optimal pH for growth was pH 4.5$\~5.8%, whereas their growth were very poor above the pH 7.2.