• Korean Journal Plant Pathology
• /
• v.10 no.1
• /
• pp.54-60
• /
• 1994

Incidence of Rhizoctonia blight ranged from 22.2% to 100% in the golf courses at six geographical locations in Korea from 1989 to 1993. Rhizoctonia blight occurred more severly in southern area than in northern area. Fifty seven isolates of Rhizoctonia solani obtained from diseased parts of zoysiagrasses were grouped to AG2-2 by anastomosis test. Pathogenicity testes revealed that this pathogen was strongly pathogenic to Korean lawngrasses(Zoysia japonica, Z. matrella, Z. tenuifolia), but not pathogenic to creeping bentgrass(Agrostis palustris), bermuldagrass(Cynodon dactylon), Kentucky bluegrass(Poa pratensis), perennial ryegrass(Lolium prenne), and creeping red fescue(Festuca rubra subsp. rubra L.). The isolation frequency of R. solani AG2-2 fro sheaths of the infected plants was the highest by 91.67%, and that from stolons and roots was 11.13% and 5.63% respectively. The pathogen was not isolated from the leaves. Population density of R. solani in the lawn of large circular patch was highest on surface soils down to 1 cm deep with the value of 4.9$\times$104 (CFU/g soil), but below 1 cm population density decreased sharply down to 0.8~9.8$\times$103 (CFU/g soil). Horizontal distribution of propagules in turfgrass soil was higher in the margin than in center of patch, where the number of propagules was similar to these of healthy looking soils close to the margin of diseased patch. The meteorological factors influencing the outbreak of the disease were temperature, the number of rainy days and precipitation. Optimum temperature for disease development of Rhizoctonia blight in field was 20~22$^{\circ}C$, and that for hyphal growth of R. solani AG2-2 in vitro was 25~3$0^{\circ}C$. In Pusan area, Rhizoctonia blight first occurred in late April and rapidly developed in late June. The disease slightly decreased during July to August and developed again in late September in 1993. The monthly disease progress in Pusan area was similar to that in Kyeonggi province.

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

• Korean Journal Plant Pathology
• /
• v.12 no.1
• /
• pp.21-32
• /
• 1996

Rhizoctonia solani 균주들의 각 균사융합군 및 배형별 72종의 기주작물에 대한 병원성을 접종실험에 의해 조사하였다. 33종의 작물에서 단독으로 분리된 균사융합군 및 배양형은 그 기주작물에 병원성이 강하였으며, 8종의 작물에서 단독으로 분리된 것들은 병원성이 약하거나 강하였고, 6조의 작물에서 단독으로 분리도니 것들은 병원성이 약하거나 없었다. 26종의 작물에서 같이 분리된 균사융합군 및 배양형은 그 기주작물에 대한 병원성이 대부분 다르거나 간혹 비슷했다. AG-1(IA)는 1종을 제외한 기주작물에 잎마름병 혹은 잎썩음병과 잎집무늬마름병을 일으켰다. AG-1(IB)는 19종의 기주작물에 잘록병과 잎마름병 혹은 잎썩음병을 일으켰으나, 9종의 기주작물에는 병징을 약하게 유발시키거나 혹은 유발시키지 못했다. AG-1(IC)는 2종의 유채속작물에 잘록병과 밑둥썩음병 혹은 잎썩음병을 일으켰다. AG-2-1은 1종을 제외한 기주작물에 잘록병, 밑둥썩음병, 관부썩음병, 눈마름벼, 뿌리썩음병, 잎마름병을 일으켰다. AG-202(IIIB)는 기주작물에 뿌리 및 줄기썩음병, 잎마름병, 잘록병, 잎자루썩음병을 일으켰다. AG-2-2(IV)는 기주작물에 잘록병, 관부썩음병, 줄기썩음병, 라이족토니아마름병을 일으켰다. AG-3은 감자에 검은무늬썩음병을 일으켰다. AG-4는 42종의 기주작물에 여러 가지 병을 일으켰으나, 3종의 기주작물에는 잘록병, 눈마름병, 잎집무늬마름병을 일으켰으나, 9종의 기주작물에는 병징을 약하게 유발시키거나 혹은 유발시키지 못했다.

• Weed & Turfgrass Science
• /
• v.2 no.2
• /
• pp.202-206
• /
• 2013

Biocontrol potential of an isolate of Helicosporium spp. against Rhizoctonia solani, Fusarium oxysporium and Phytophthora drechsleri was evaluated in vitro and in vivo. A selected biocontrol agent designated as Helicosporium 0635BP strongly inhibited growth and lysed mycelium of Rhizoctonia solani and Fusarium oxysporium on PDA. Autoclaved culture filtrate of the agent also completely inhibited growth of the turfgrass large patch pathogen, R. solani AG2-2 IV at the concentration of 50 ml $L^{-1}$. The pathogen was killed when dipped under the 20% filtrate for four hours or 50% for one hr. In a field trial, plots applied with the crude or times diluted culture filtrate showed 100% control efficacy of the turfgrass large patch as a chemical applied for a comparison. Results indicated that Helicosporium 0635BP is a promising biocontrol agent on control of the turfgrass large patch disease and its culture filtrate contained unknown heat suitable antifungal substance (s). Further studies on mass production, purification and identification of the unknown compound (s) are in progress for practical use.

• Journal of Life Science
• /
• v.12 no.2
• /
• pp.200-207
• /
• 2002

This study was carried out to isolate of antagonistic bacterium against Pythium ultimum and Rhizoctonia solani AG-4, causal pathogens of vegetables damping-off. Total of 600 strains were isolated from soil and plait roots. The isolates were screened for antagonism against Pythium ultimum and Rhizoctonia solani AG-4. One strain, named YJ-37, was sellected for detained study among those microoganisms screened. It was identified as Bacillus ehimensis based on morphological and physiological characterisitics according to the Bergey's mannual of systematic bacteriology, Sherlock system of Microbial ID Inc. and 16S rDNA sequences methods. Furthermore Bacillus ehimensis YJ-37 showed antifungal activities against Alternaria altrata, Collectotrichum gloeosporioides, Didymella bryoniae, Fusarium moniliforme, Fusarium oxysporum, F. oxysporum cucumerinum, F. oxysporum niveum, Gloeosporium sp., Glomerella sp., G. cingulata, G. lagenaria, Penicillium digitatum, P. italicum, Phytophthora capsici, Sclerotinia sclerotiorum, and Stemprhylium solani.

• Microbiology and Biotechnology Letters
• /
• v.33 no.2
• /
• pp.112-116
• /
• 2005

Bacillus licheniformis KMU-3 shown a strong antifungal activity was isolated from Swedish forest soils. B. licheniformis KMU-3 produced a maximum level of antifungal substance under incubation aerobically at $24^{\circ}C$ for 24 hours in LB broth containing $1.0\%$ sodium acetate, $1.0\%$ ammonium sulfate at 180 rpm and initial pH adjusted to 8.0. Chloroform extraction of culture broth was confirmed inhibitory zone by plate assay and Rf value 0.49 substance by thin layer chromatography (TLC) represented high antifungal activity against Rhizoctonia solani AG-1. This substance also exhibited against Rhizoctonia solani AG-4, Colletotrichum orbiculare, Colletotrichum gloeosporioides, Cladosporium cucumerinum, Fusarium oxysporum, and Fusarium graminearum.

• The Korean Journal of Mycology
• /
• v.26 no.3 s.86
• /
• pp.373-379
• /
• 1998

Rhizoctonia solani [Thanatephorus cucumeris (frank) Donk], one of the major soil-borne plant pathogens with world-wide distribution, can cause great damages on various crops. In Korea, sheath blight on rice caused by this pathogen is the major concern, and active studies on this pathogen have been performed. However, most of these studies were concerned with pathogenicity of the isolates instead of molecular analyses of different AGs of R. solani. Therefore, in this study, thirty isolates of Rhizoctonia solani collected from various sources were used for the analyses of genetic relationships among themselves and for the rapid anastomosis grouping with RAPD method. As a result, thirty isolates of known and unknown AGs were grouped into five subgroups and each group included AG-1, AG-2, AG-3, AG-4, and AG-5. RS-1 isolate was found to be closely related to AG-5. Isolates RS-4, RS-14, RS-17, and RS-16 were found to be closely related to AG-2-2(III B). Isolate RS-13 was closely related to AG-4, isolates RS-8 and RS-10 were closely related to AG-1(I B), and isolates RS-7 and RS-21 were closely related to AG-2-2(IV). Isolate RS-19 was closely related to AG-1(I C), and isolates RS-3, RS-5, RS-18, RS-6, and RS-15 were found to be closely related to AG-1.

• The Plant Pathology Journal
• /
• v.26 no.1
• /
• pp.83-89
• /
• 2010

Taxonomic position of 46 Korean isolates of Rhizoctonia solani which were classified into nine intraspecific groups by anastomosis and cultural characteristics was analyzed by randomly amplified polymorphic DNA (RAPD) and sequence analyses of the internal transcribed spacer (ITS) regions of ribosomal DNA. All the isolates within each group showed highly similar band patterns in RAPD. The ITS regions of the isolates within the same groups showed a high level of sequence similarity above 96.0% whereas similarities among different groups were below 94.4%. When compared with several reference strains of R. solani from foreign countries, all the Korean isolates were clustered with the foreign isolates belonging to the same groups in the phylogenetic tree. All six Korean strains of AG-4 were identified as HG-1 out of 3 subgroup of AG-4. We discussed taxonomic position of Korean isolates of R. solani and showed that sequence analysis with ITS regions could be a rapid and useful method for identification of intraspecific group of R. solani.

• The Plant Pathology Journal
• /
• v.27 no.1
• /
• pp.68-77
• /
• 2011

Fifty five species of medicinal plant materials were tested for their antifungal activity in vitro against Rhizoctonia solani AG 2-1 and Trichoderma harzianum to select plant species that can be used to improve the biocontrol efficacy of T. harzianum. Six species were effective against R. solani AG 2-1 but were also antagonistic to T. harzianum, except for Cinnamomum loureirii stem bark (CSB). CSB inhibited mycelial growth of R. solani AG 2-1 by 73.7% but showed an inhibitory effect on mycelial growth of T. harzianum by only 2.2%. Scanning electron microscophs showed that the CSB treatment resulted in deformed R. solani AG 2-1 hyphal cells, and transmission electron microscophs revealed degenerated cell structures such as degenerated cytoplasm and disentangled cell wall and the accumulation of electron-dense inclusions (asterisks) in the CSB treatment. The biocontrol efficacy of radish damping-off increased greatly following the combined treatments of T. harzianum and CSB and the combined treatment increased efficacy from 6.4-23.1% to 37.1-87.3% compared with either treatment alone. CSB did not affect T. harzianum population growth, as it was almost the same in rice-bran peat medium (culture) amended with 0.1% and 1.0% CSB powder as in non-amended medium. The formulation of T. harzianum in rice-bran peat medium amended with CSB powder reduced the severity of radish damping-off by 80.6%, suggesting that T. harzianum and CSB can be formulated as a biocontrol product for the control of R. solani AG 2-1.

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