• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.379-386
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• 2011

The objective of this work was to investigate the ability of the plant growth-promoting rhizobacterium Pseudomonas aureofaciens 63-28 to induce plant defense systems, including defense-related enzyme levels and expression of defense-related isoenzymes, and isoflavone production, leading to improved resistance to the phytopathogen Rhizoctonia solani AG-4 in soybean seedlings. Seven-day-old soybean seedlings were inoculated with P. aureofaciens 63-28, R. solani AG-4, or P. aureofaciens 63-28 plus R. solani AG-4 (P+R), or not inoculated (control). After 7 days of incubation, roots treated with R. solani AG-4 had obvious damping-off symptoms, but P+R-treated soybean plants had less disease development, indicating suppression of R. solani AG-4 in soybean seedlings. Superoxide dismutase (SOD) and catalase (CAT) activities of R. solani AG-4-treated roots increased by 24.6% and 54.0%, respectively, compared with control roots. Ascorbate peroxidase (APX) and phenylalanine ammonia lyase (PAL) activities of R. solani AG-4-treated roots were increased by 75.1% and 23.6%, respectively. Polyphenol oxidase (PPO) activity in soybean roots challenged with P. aureofaciens 63-28 and P+R increased by 25.0% and 11.6%, respectively. Mn-SOD (S1 band on gel) and Fe-SOD (S2) were strongly induced in P+R-treated roots, whereas one CAT (C1) and one APX (A3) were strongly induced in R. solani AG-4- treated roots. The total isoflavone concentration in P+Rtreated shoots was 27.2% greater than the control treatment. The isoflavone yield of R. solani AG-4-treated shoots was 60.9% less than the control.

• The Korean Journal of Mycology
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• v.23 no.3 s.74
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• pp.257-265
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• 1995

Morphological characteristics and pathogenicity of Rhizoctonia species causing blight diseases of turfgrasses were studied. The species were identified as Rhizoctonia cerealis Van der Hoeven, R. oryzae Ryker et Gooch, and R. solani $K{\ddot{u}hn}$ based on their morphological and cultural characteristics. Isolates of R. solani were assigned to anastomosis groups (AG) with cultural type 1 (1A), 2-2 (IIIB), and 2-2 (IV). R. cerealis, R. oryzae and R. solani induced sheath rot and foliar blight symptoms on creeping bentgrass (Agrostis palustris) and zoysiagrass (Zoysia japonica). Inoculation tests showed that disease severity with isolates of R. cerealis and R. oryzae were more serious to creeping bentgrass than zoysiagrass. AG 1(1A) isolates of R. solani were strongly pathogenic on creeping bentgrass, but moderate to zoysiagrass. AG 2-2 (III) isolates were moderately pathogenic to zoysiagrass, but weakly to creeping bentgrass. AG 2-2 (IV) isolates from zoysiagrass were moderately pathogenic to zoysiagrass, but weakly to creeping bentgrass.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.266-270
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• 2012

Stem canker and tuber rot symptoms were observed on yam grown in Andong and Jinju, Korea in 2011. A total of 20 isolates of Rhizoctonia and allied fungi were obtained from the symptomatic plants. Among the isolates, 8 isolates were identified as Rhizoctonia solani and 12 isolates as Ceratobasidium sp. based on rDNA-internal transcribed spacer (ITS) sequence similarity. In the cluster analysis of rDNA-ITS sequences, 7 isolates of R. solani belonged to AG 2-2IIIB and remaining one to AG 1-1A. In addition, among the 12 isolates of Ceratobasidium sp., 7 isolates belonged to AG-Fa, three isolates to AG-A and the other two isolates to AG-Fb and AG-O, respectively. Pathogenicity tests showed that all the R. solani AG 2-2IIIB isolates are pathogenic on stem and tuber of yam but R. solani AG 1-1A and all the Ceratobasidium isolates are non-pathogenic. The results indicate that R. solani AG 2-2IIIB is an important pathogen causing stem canker and tuber rot on yams grown in the study areas. This is the first report of R. solani AG 2-2IIIB causing stem canker and tuber rot of yam in Korea.

• The Korean Journal of Mycology
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• v.18 no.3
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• pp.164-177
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• 1990

This study was carried out to obtain some useful data for increasing an effective ginseng production. There was a direct relationship (r=0.2645) between spore germination of Fusarium solani and soil pH, and (r=0.315) between Cylindrocarpon destructans and soil pH. On the other hand, there was a direct relationship (r=0.19) between relative hyphal growth of Rhizoctonia solani and soil pH. There was a direct relationship (r=0.21) between number of total bacteria and F. solani, (r=0.37) between actinomycetes and F. solani and (r=0.20) between celluloytic bacteria and F. solani. However, there was an inverse relationship (r=-0.20) between number of total fungi and F. solani. There was a direct relationship (r=0.24) between number of actinomycetes and R. solani. Each ginseng pathogen-suppressive soil screened was 40 in F. solani, 20 in C. destructans and 9 soil samples in R. solani among 146 soil samples, respectively. The mean contents of K, Ca and Mg were fairly lower in each ginseng pathogen-suppressive soil than conducive soil, whereas Na were somewhat lower. The mean contents of organic matter were over 2 times higher in each ginseng pathogen-suppressive soil than conducive soil. The mean contents of phosphate were fairly lower in F. solani and R. solani-suppressive soil than conducive soil and, on the other hand, were somewhat higher in C. destructans-suppressive soil than conducive soil. The mean soil pH was somewhat lower in each ginseng pathogen-suppressive soil than conducive soil. The mean contents of sand were about 2 times higher in each ginseng pathogen­suppressive soil than conducive soil, whereas silt and clay were somewhat lower. The microbial numbers of total bacteria, total fungi and celluloytic fungi were higher in F. solani-suppressive soil than conducive soil, whereas actinomycetes and celluloytic bacteria were lower. Each microbial number of total bacteria or total fungi indicated a significant difference (p=0.05) between F. solani­suppressive and conducive soil, and the microbial number of actinomycetes was a highly significant difference (p=0.01) between F. solani-suppressive and conducive soil. The microbial numbers of total bacteria, total fungi, actinomycetes and celluloytic fungi were higher in C. destructans-suppressive soil than conducive soil, whereas celluloytic bacteria were about 2 times lower. On the other hand, the microbial numbers of total fungi were higher in R. solani-suppressive soil than conducive soil, whereas total bacteria, actinomycetes, celluloytic bacteria and celluloytic fungi were lower. Fourteen of 16 F. solani-suppressive soils tested were suppressive to ginseng root rot, whereas fifteen of 16 C. destructans-suppressive soils were suppressive. Ginseng root rots of ginseng disease-suppressive soils were in the range of 1.0-17.4% in F. solani-suppressive soil and 0.2-20.4% in C. destructans-suppressive soil, respectively.

• Asian Journal of Turfgrass Science
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• v.12 no.3
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• pp.183-194
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• 1998

Of crude extracts from 30 species belonging to the 21 families of medical plants, the crude extracts from Cinnamomum cassia, Paeonia moutan, Dictamnus dasycarpus showed highly antifungal activities against Rhizoctonia solani AG1-1 and R. solani AG2-2. The antifungal activity of C. cassia and P. moutan against R. solani AG1-1 were the highest through 100% methanol extraction, but the one of D. dasycarpus were the highest through 80% methanol extraction. On the other hand, against R. solani AG2-2 the antifungal activity of them were the highest through 100% methanol. C. cassia P. mouton and D. dasycarpus showed over 60% inhibition of mycelial growth against R. solani AG1-1 and R. solani AG2-2 on up to 500 fold dilution. The crude extract of P. moutan showed broader antifungal spectrum compared with those of C. cassia and D. dasycarpus. The crude extract of C. cassia was not phytotoxic at over 250 fold dilution and the crude extract of P. moutan was not phytotoxic at over 100 fold dilution. The crude extract of D. dasycarpus was not phytotoxic even at full concentration. The control values of P. moutan and D. dasycarpus were increased 75.0% and 79.1% respectively 30 days after treatment.

• Korean Journal Plant Pathology
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• v.10 no.4
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• pp.314-318
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• 1994

Incidence of stem rot on carnation (Dianthus caryophyllus L.) ranged 11 to 29% in Namwon and Chongup area during the growing seasons from 1993 to 1994. Among 129 isolates from carnations in Namwon, 77 isolates were identified as Rhizoctonia solani, 38 isolates were Fusarium oxysporum and 14 isolates were not identified. Among 169 isolates in Chongup, 19 isolates were identified as R. solani, 106 isolates as F. oxysporum and 44 isolates were not identified. Among 77 isolates of R. solani isolated from the specimens of Namwon, 52 isolates were classified as anastomosis group AG 2-2 by anastomosis test, 14 isolates as AG 2-1 and 11 isolates as AG 4. Among 19 isolates from specimens of Chongup, 14 isolates were classified as anastomosis group AG 2-2 and 5 isolates as AG 4. Pathogenicity tests revealed that isolates of F. oxysporum and R.solani AG 2-2 were highly virulent and isolates of R.solani AG 2-1 and AG 4 were mildly virulent.

• Asian Journal of Turfgrass Science
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• v.12 no.4
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• pp.211-220
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• 1998

Cellulose-degrading fungi were idenfied as Rhizoctonia solani AG2-2(IV), T. harzianum and C. cochliodes. Rhizoctonia solani AG2-2(IV) grows better in the acidified media of pH 4 and 5 than pH 6 and 7. Mycelial growth of T. harzianum and C. cochliodes was also higher in pH 4 and 5 than in pH 6 and 7. In order to relate the above findings to nutrient utilization, mycelial growth of R. solani AG2-2(IV) are evaluated with various carbon sources. R. solani AG2-2(IV) grows well in the order of mannose, cellobiose, glucose, xylose and arabinose. However, mycelial dry weights of T. harzianum were 98.7, 78.0, 72.3, 43.7 and 32.3mg in glucose, mannose, cellobiose, xylose, and arabinose, respectively. Mycelial dry weight of C. cochilodes was 118, 65, 57, 49, and 16mg in mannose, cellobiose, xylose, glucose, and arabinose, respectively. Result of cellulase assay of R. solani AG2-2(IV) and soil fungi was reffered as, R. solani AG2-2(IV) produced more cellulase on CMC substrate than on CEL and secretes more enzyme in floated condition than in water-immersed condition. T. harzianum secreted less amount of cellulase than R. solani AG2-2 and C. cochliodes. T. harzianum produced no enzyme on CEL under water-immersed condition. C. cochliodes produced similar amounts of cellulase on either CMC or CEL under both water-immersed and floated condition.

• Research in Plant Disease
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• v.29 no.4
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• pp.377-383
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• 2023

In 2020 and 2021, we surveyed diseases of three-leaf ladybell (Adenophora triphylla) plants grown in fields at two locations in Korea. During the disease surveys, severe leaf rot symptoms were observed on the young plants in Hongseong, and stem rot symptoms on the adult plants in Cheolwon. The incidence of leaf rot was 5-60%, and that of stem rot 1-10%. We obtained 6 fungal isolates each from the leaf rot lesions and the stem rot lesions. All the isolates were morphologically identified as Rhizoctonia solani. Anastomosis test and investigation of cultural features of the fungal isolates revealed that the isolates from the leaf rot lesions corresponded to R. solani AG-1(IB), and those from the stem rot lesions to R. solani AG-2-2(IIIB). Two isolates each of R. solani AG-1(IB) and AG-2-2(IIIB) were used for DNA sequence analysis and pathogenicity test to three-leaf ladybell plants through artificial inoculation. The anastomosis groups and cultural types of the R. solani isolates were confirmed by the sequence analysis. The pathogenicity tests revealed that the isolates of R. solani AG-1(IB) caused only leaf rot symptoms on the inoculated plants, and those of R. solani AG-2-2(IIIB) leaf rot and stem rot symptoms. The induced symptoms were similar to those observed in the fields investigated. Leaf and stem rot of three-leaf ladybell caused by the two anastomosis groups and cultural types of R. solani is first reported in this study.

• Journal of Life Science
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• v.13 no.3
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• pp.355-358
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• 2003

Various Trichoderma spp. were evaluated for the development of biofungicides to control soilborne pathogen, Rhiztonia solani, Various Trichoderma spp. were initially tested for their ability to inhibit growth of R. solani by inhibition zone test. Inhibition zones of 3∼5 mm toward R. solani were detected on PDA agar plates. The parasitic activity of strains, the activities of cell-wall-degrading enzymes such as glucanases and chitinases, were also evaluated. Highest activities of glucanase and chitinase were 3.5 U/ml and 0.9 U/ml, respectively, Isolated Trichoderma spp. also exhibited good growth with currently used agrochemicals, which represents that the isolated biofungicides can be mutually used with agrochemicals.

• Asian Journal of Turfgrass Science
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• v.6 no.2
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• pp.89-98
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• 1992

Cultural characteristics and pathogenicity on the isolates of Rhizoctonia oryzae, R. oryzae-sativae and anastomosis group of R. solani and evaluation of selected fungicides on brown patch disease of creeping bentgrass and large patch disease of zoysia grass were studied comparatively. From effect of temperature on the rate of mycelia growth, the result indicated that the temperature groups were separated into four types : isolates of R. oryzae and R. oryzae-sativae had an optimum temperature of $30~35^{\circ}C$. Anastomosis groups of R. solani were separated into three temperature types as followings : high temperature type had an optimum temperature from 25 to $30^{\circ}C$, moderate type had grown from 20 to $25^{\circ}C$ for optimum and low temperature type had an optimum temperature of $20^{\circ}C$ but at $35^{\circ}C$ did not grow. Inoculation tests showed that AG-1( I A), AG-1( I B), bentgrass isolate of R. solani and R. oryzae were strongly pathogenic on creeping bentgrass, followed by AG-2-1, AG-4, AG-5 and AG-2-2 isolates of R. solani moderately to weakly. Zoysia grass isolate of R. solani and R. oryzae were strongly pathogenic on zoysia grass but AG-1( I B) and AG-5 isolates of R. solani showed moderately pathogenic. Capro(iprodione oxine-copper) and mytan(myclobutanil) were extremely effective against brown patch disease of creeping bentgrass and large patch disease of zoysia grass followed by thiopan (thiopanate-methyl) and pencycuron for brown patch disease and tolos(tolclofos-methyl) and thiopan for large patch disease.