• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.35-40
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• 2005

Damping-off of summer spinach caused by Rhizoctonia solani AG-4 has become a very important disease. For the control of summer spinach damping-off, antifungal activity of thirteen fungicides (pencycuron, trifloxystrobin, pyraclostrobin, azoxystrobin, kresoxim-methyl, validamycin, fluazinam, Benlate-T, flutolanil, cyazofamid, hexaconazole, tebuconazole, prochloraz) were evaluated in vitro and in vivo. Pencycuron, pyraclostrobin, validamycin, fluazinam, Benlate-T, hexaconazole, tebuconazole, and flutolanil significantly suppressed the mycelial growth of the pathogenic fungus. However, trifloxystrobin, azoxystrobia kresoxim-methyl, cyazofamid, and prochloraz did not represent good inhibition on the growth of R. solani. When applied by soil drenching (2,000 mg/L), pencycuron, pyraclostrobin, validamycin, fluazinam, Benlate-T, and flutolanil provided spinach survival ratios of 97.8%, 84.4%, 93.3%, 95.6%, 91.1%, and 86.7%, respectively. Also when treated in seed at 2,000 ing/L, pencycuron and pyraclostrobin displayed survival ratios of more than 85.1%.

• The Korean Journal of Mycology
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• v.44 no.3
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• pp.176-183
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• 2016

Bacillus velezensis CC112 inhibited the mycelial growth of several plant pathogens, including Rhizoctonia solani, causing damping-off on ginseng. The control efficacies of B. velezensis CC112 against R. solani by seed dipping in LB and BSM broth diluted 10 times, soil dipping, and soil drenching with LB broth diluted 10 times were 65.8%, 67.1%, and 64.2%, respectively. Treatment of soil drenching with the 100 times diluted prototype of B. velezensis CC112 against R. solani and Pythium sp. by soil revealed control efficacies of 77.3% and 65.7%, respectively. These results indicate that B. velezensis CC112 is a prospective biofungicide for the biological control of ginseng damping off.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.406-408
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• 2005

Web blight symptoms were frequently observed on soybean plants grown in a farmer's fields located in Jincheon in Korea during a disease survey in August, 2005. Incidence of the disease was $5-20\%$ infected plants in two of four soybean fields investigated. A total of 31 isolates of Rhizoctonia sp. were obtained from leaves, leaf petioles, and pods of diseased soybean plants. The isolates were identified as Rhizoctonia solani AG-l(IA) by anastomosis test and based on the morphological and cultural characteristics. Three isolates of R. solani AG-l(IA) were tested for pathogenicity to five cultivars of soybean by artificial inoculation. All the isolates induced blight symptoms on the leaves of soybean and formed sclerotia on the lesions, which were similar to those observed in the field. The pathogenicity tests revealed that all the soybean cultivars tested were susceptible to the pathogen. There was no difference in the pathogenicity among the isolates. The present study first reveals that R. solani AG-l(IA) causes web blight of soybean in Korea.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.596-606
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• 2021

Soil-borne diseases are the major problems in mono cropping. A mixture (designated LTM-m) composed of agricultural wastes and a beneficial microorganism Streptomyces saraceticus SS31 was used as soil amendments to evaluate its efficacy for managing Rhizoctonia solani and root knot nematode (Meloidogyne incognita). In vitro antagonistic assays revealed that SS31 spore suspensions and culture broths effectively suppressed the growth of R. solani, reduced nematode egg hatching, and increased juvenile mortality. Assays using two Petri dishes revealed that LTM-m produced volatile compounds to inhibit the growth of R. solani and cause mortality to the root knot nematode eggs and juveniles. Pot and greenhouse tests showed that application of 0.08% LTM-m could achieve a great reduction of both diseases and significantly increase plant fresh weight. Greenhouse trials revealed that application of LTM-m could change soil properties, including soil pH value, electric conductivity, and soil organic matter. Our results indicate that application of LTM-m bio-organic amendments could effectively manage soil-borne pathogens.

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.296-304
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• 1994

Antibiotic substances were produced by Bacillus subtilis YB-70, a potential biocontrol agent found to suppress root-rot of eggplant (Solanum melonggena L) caused by Fusarium solani, in a dextrose glutamate medium and isolated by isoelectric precipitation. Partial purification was performed by column chromatography on silica gel with two solvent systems: chloroform-methanol and methanol-chloroform-water as eluting solvents, This active fraction YBS-1 s contained antifungal activity were soluble in ethanol, methanol, and water, but were not soluble in other solvents including acetone, butanol, ethyl ether, dimethylformamide, propanol, and etc. High performance liquid chromatography and thin layer chromatographic separation of YBS-1s showed that they have been composed of three biological active bands that were named YBS-1A, -1B, and -1C. The substances were stable to heat and resistant to protease. YBS-1s were active against a wide range of plant pathogenic fungi but did not inhibit the growth of bacteria and yeasts. They were not only fungicidal but also fungistatic against chlamydospores of F. solani. The $ED_{50}$ values for the chlamydospore germination and the germ-tube growth of F. solani were $O.725\mu\textrm{m}/ml\;and\;O.562\mu\textrm{m}/ml$, respectively. Microscopic observations proved the substances restricted the growth of phytopathogenic fungus F. solani by spore burst followed by dissolving of its germ-tube, and caused abnormal hyphal swelling after application to chlamydospores or growing hyphae. Cultural filtrate of B; subtilis YB-70 also suppressed the development of root-rot of eggplant in pot tests.

• The Korean Journal of Mycology
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• v.21 no.3
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• pp.188-194
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• 1993

Anastomosis types and hyphal interactions in culture among different location and field isolates of Rhizoctonia solani AG-1(IA), R. oryzae and R. oryzae-sativae were examined. In the pairings of R. solani AG-1(IA) isolates, cytoplasmic fusion only occurred in the self-anastomoses, and non-cytoplasmic fusion occurred in the other combinations. In the pairings of R. oryzae isolates, cytoplasmic fusion occurred in six combinations between different location isolates and in two combinations between different field isolates from the same locations as well as in the self-anastomoses. In that case, four isolates of the fungus reciprocally made the cytoplasmic fusion. In the pairings of R. oryzae-sativae isolates, only non-cytoplasmic fusion occurred among the different location and field isolates, in which cytoplasmic fusion also occurred in the self-anastomoses. When non-cytoplasmic fusion isolates(NCFIs) of R. solani AG-1(IA) were opposed on PDA, a killing zone developed between the NCFls paired after incubation. The killing zone also developed between the NCFls of R. oryzae paired. No killing zone developed between the cytoplasmic fusion isolates(CFIs) of R. oryzae, in which mycelia of the CFIs intermingled with each other without formation of any demarcation line. An entangled zone instead of the killing zone developed between the NCFIs of R. oryzae-sativae.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.657-665
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• 2013

A large patch disease caused by Rhizoctonia solani AG2-2 (IV) is a serious problem in Korean lawngrass (Zoysia japonica) sites including golf courses and sports fields in Korea. Antagonistic microorganisms against R. solani AG2-2 (IV) were isolated from various forest and crop soil sources in Southern Korea. Among the 61 isolates, I-009, FRIN-001-1, and YPIN-022 strains showing dramatic inhibition of the mycelial growth of R. solani AG2-2 (IV) in the pairing culture were selected as the most potential antagonistic microorganisms for this study. Based on the 16s RNA sequence comparison, I-009 and FRIN-001-1 isolates were identified as Bacillus spp., while YPIN-022 isolate belongs to the genus Pseudomonas. The greater inhibition (clear) zone between two edges of the selected and pathogenic microbes ranged from 11 to 15 mm in three selections, but the others averaged to 7 mm out of 30 mm distance. In another antifungal test using culture filtrate, those three isolates represented a range of 51.7 to 63.5% suppression potential. The selected isolates also inhibited significantly the stem-segment colonization by R. solani AG2-2 (IV) in vivo test by 28.1%, 43.0%, and 23.7% when inoculated with I-009, FRIN-001-1, and YPIN-022, respectively. The highest antagonistic activity for the large patch disease was demonstrated by the isolate FRIN-001-1, which will be useful for developing a bio-pesticide against Rhizoctonia.

• 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.

• The Korean Journal of Mycology
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• v.20 no.1
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• pp.44-50
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• 1992

The protoplast formation of Rhizoctonia solani in the fast growing anastomosis groups (AGs) 1 and 4, the intermediate AG-2 and AG-5, and the slow AG-3 yielded the most, moderate and the least in that order, respectively. Sclerotia formation varied with AGs. A high yield of protoplasts from AGs was obtained with a combined lytic enzyme system containing cellulase 'Onozuka' R-10, macerozyme R-10 and ${\beta}-glucuronidase$. When 3g (fresh weight) of 30 hr old mycelia was incubated for 3 hr at $32^{\circ}C$ with the enzyme mixture in 0.6 M mannitol, maximum protoplasts were obtained in the five AGs. A protoplast fusion between sclerotia forming AG-1 inactivated with heat and non-forming AG-5 was induced by polyethylene glycol and ${Ca}^{2+}$. Seven fusants obtained were based on characteristics of colony and sclerotium formation on culture plates. The fusants were confirmed by isozyme patterns of esterase and killing reaction between AG-1 and a fusant F1501.

• The Plant Pathology Journal
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• v.28 no.2
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• pp.156-163
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• 2012

Stem rots caused by Rhizoctonia solani and Sclerotinia sclerotiorum have been known as devastating diseases in balloon flower plants. Antifungal activities of four fungicides, azoxystrobin, polyoxin B, trifloxystrobin and validamycin A were evaluated in vitro, showing effective suppression with mycelial growth of the fungal isolates on PDA media. Efficacies of the four fungicides were also demonstrated in stem tissues of balloon flower plants against R. solani and S. sclerotiorum. A commercially available Bacillus subtilis strain Y1336 was tested in terms of antagonistic biological control of stem rot disease of balloon flower plants. The bacterial strain revealed its antifungal activities against R. solani and S. sclerotiorum demonstrated by dual culture tests using paper discs and two plant pathogenic fungi on PDA media, as well as by plant inoculation assay, indicating that this antagonistic bacterial strain can be incorporated into disease management program for balloon flower stem rot diseases together with the four chemical fungicides.