• The Korean Journal of Mycology
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• v.50 no.4
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• pp.357-360
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• 2022

In July 2021, we surveyed diseases affecting wild vegetables grown in Hongcheon, Gangwon Province, Korea. During this survey, we observed severe seedling rot symptoms in Kamchatka goatsbeard (Aruncus dioicus) grown in a vinyl greenhouse. The incidence of the disease in the plant seedlings was 1-10%. Diseased seedlings from this population were collected, and fungi were isolated from leaf and petiole lesions. Rhizoctonia sp. was consistently isolated from the lesions. We examined the morphological and cultural characteristics and anastomosis groups of nine Rhizoctonia sp. isolates obtained from the lesions. The results revealed that all isolates corresponded to Rhizoctonia solani AG-1(IB). Three isolates of R. solani AG-1( IB) were evaluated to determine their pathogenicity towards Kamchatka goatsbeard seedlings through artificial inoculation. The tested isolates caused rot symptoms on the inoculated plant seedlings. The symptoms were similar to those observed in plant seedlings from the vinyl greenhouse. We found that R. solani AG-1(IB) caused seedling rot of Kamchatka goatsbeard.

• The Korean Journal of Mycology
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• v.49 no.2
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• pp.249-251
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• 2021

Damping-off symptoms were frequently observed in young deltoid synurus (Synurus deltoides) plants grown in a farmer's vinyl greenhouse located in Hwacheon, Gangwon Province, Korea, during a disease survey in July 2019. The incidence of diseased plants in the vinyl greenhouse investigated was 5-30%. Five isolates of Rhizoctonia sp. were obtained from the diseased plants and identified as Rhizoctonia solani AG-1 (IB), based on morphological and cultural characteristics and anastomosis test results. Three isolates of R. solani AG-1 (IB) were tested for pathogenicity on deltoid synurus using artificial inoculation. All the tested isolates induced damping-off symptoms in the inoculated plants. The symptoms were similar to those observed in plants from the farmer's vinyl greenhouse. To our best knowledge, this is the first report of R. solani AG-1 (IB) causing damping-off in deltoid synurus.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.88-94
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• 2013

Brown patch caused by Rhizoctonia solani AG-1 IB occurred on Kentucky bluegrass during late May through early October 2010 at golf course in Gyeongbuk Province, Korea. Disease symptoms on the turfgrass for spring season were leaf blights dying from the leaf tip, which appeared patches of brown color in the field. However, it appeared patches of dark brown color or gray brown color in fall. The fungus (B-7 isolate) of brown patch was isolated from the diseased leaf tissue and cultured on potato-dextrose agar (PDA) for identification. The young hyphae had acute angular branching and few septa and mature hyphal branches showed about 90-degree angles and development of monilioid cells, which were morphologically identical to Rhizoctonia solani AG-1 IB reported previously. DNA sequences of ribosomal RNA gene (internal transcribed spacer) of the fungus were homologous with similarity of 99% to those of Rhizoctonia solani AG-1 IB isolates in GenBank database, confirming the identity of the causal agent of the disease. Pathogenicity of the fungus was also confirmed on the creeping bentgrass and Kentucky bluegrass by Koch's postulates. This is the first report of brown patch on Kentucky bluegrass caused by Rhizoctonia solani AG-1 IB in Korea.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.7-12
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• 1994

Incidence of radish disease caused by Rhizoctonia solani ranged from 1 to 30% in fields located at Hwaseong, Naju and Yeoncheon in Korea during the growing seasons in 1989, 1990 ad 1993. A total of 133 isolates of R. solani was obtained from the diseased seedlings, leaves and roots of radish collected. The fungus was most commonly isolated from the roots. Among 133 isolates of R. solani, 56 isolates were classified as anastomosis group AG-1 by anastomosis test, 37 isolates as AG-2-1, and 40 isolates as AG-4. Among the isolates of AG-1, 26 isolates were grouped as cultural type IA, and the others as cultural type IB. Cultural types IA and IB of AG-1, were isolated from the leaves, AG-2-1 from the roots, and AG-4 from the seedlings, leaves and roots. Pathogenicity tests revealed that the AG-1(IA) isolates were highly virulent on leaves of radish, but avirulent on the seedlings, petioles and roots. The AG-1(IB) isolates were highly virulent on the leaves, but mildly virulent on the seedlings and avirulent or mildly virulent on the petioles and roots. The AG-2-1, isolates were mildly virulent on the leaves and seedlings and mildly or highly virulent on the petioles and roots. The AG-4 isolates were highly virulent on the seedlings and mildly or highly virulent on the leaves, petioles and roots.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.387-394
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• 2013

The Rhizoctonia blight causing by Rhizoctonia spp. is an important disease of turfgrass, requiring fungicide application to maintain acceptable conditions for turfgrass good qualities in the golf course. The experiment was conducted to determine the mean 50% effective concentration inhibiting mycelial growth ($EC_{50}$) value of to flutolanil, pyraclostrobine and hexaconazole to Rhizoctonia solani AG-1 IB, Rhizoctonia cerealis and Rhizoctonia solani AG2-2IV isolated from Gyeongbuk province of Korea in vitro. Five discriminatory concentrations of each fungicide were used to detect in vitro sensitivity. The mean of $EC_{50}$ values to three systemic fungicides was the lowest isolate of R. solani AG-1 IB. However, the sensitivity of fungicides to Rhizoctonia solani AG2-2IV were higher mean $EC_{50}$ value of 0.026 ${\mu}g\;a.i.\;ml^{-1}$ of pyraclostrobine and 0.044 ${\mu}g\;a.i.\;ml^{-1}$ of flutolanil. R. cerealis was the lowest sensitivity to hexaconazole which was an average $EC_{50}$ value of 0.022 ${\mu}g\;a.i.\;ml^{-1}$. Inhibition of mycelial growth rate (%) by three combine fungicides using the $EC_{50}$ value of each fungicide was the highest R. solani AG2-2IV. Results of this study were may confirmed in vitro response fungicide of three Rhizoctonia species for control of Rhizoctonia blight in the field.

• Korean Journal Plant Pathology
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• v.1 no.1
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• pp.72-78
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• 1985

The effects of temperature. pH, carbon and nitrogen sources on the growth of Rhizoctonia solani were studied by using five hyphal anastomosis groups(four cultural types, 7 isolates) of the fungus. The ranges of optimum temperature were $20^{\circ}C$ in the AG 2-1, AG 2-2 and AG 4, and $25^{\circ}C$ in the AG 1-IA, AG 1-IB, AG 3, AG 5. The optimum pH for the mycelial growth was 6-7 in the fungus. Glucose in the AG 1-lA, AG 1-IB, AG 2-2, AG 3 and AG 5, sucrose in the AG 2-1 and fructose in the AG 4 were the most effective for the mycelial growth, but glycerine, cellulose and lactose were not effectively utilized as nutrients. $Ca(NO_3)_2$ in the AG 1-IA, AG 1-IB and AG 4, asparagine in the AG 2-1, $KNO_3$ in the AG 2-2 and $NaNO_3$ in the AG 5 were the best nitrogen sources for the mycelial growth, but $NH_4NO_3$ was not easily utilized by the fungus. Nitrate and organic nitrogens for the fungal growth were utilized better than ammonium nitrogen.

• Mycobiology
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• v.43 no.2
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• pp.170-173
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• 2015

Herein, we report the first occurrence of web blight of rosemary caused by Rhizoctonia solani AG-1-IB in Gangneung, Gangwon Province, Korea, in August 2014. The leaf tissues of infected rosemary plants were blighted and white mycelial growth was seen on the stems. The fungus was isolated from diseased leaf tissue and cultured on potato dextrose agar for identification. The young hyphae had acute angular branching near the distal septum of the multinucleate cells and mature hyphal branches formed at an approximately $90^{\circ}$ angle. This is morphologically identical to R. solani AG-1-IB, as per previous reports. rDNA-ITS sequences of the fungus were homologous to those of R. solani AG-1-IB isolates in the GenBank database with a similarity percentage of 99%, thereby confirming the identity of the causative agent of the disease. Pathogenicity of the fungus in rosemary plants was also confirmed by Koch's postulates.

• 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.

• Korean Journal of Microbiology
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• v.36 no.1
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• pp.40-45
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• 2000

Rhizoctonia solani Kuhn[Thanatephorus cucumeris (Frank) Donk]is a destrutive soil-borne plant pathogen affecting many agricultural crops worldwide. R. solani is divided into anastomosis groups based on the ability of the hyphae to fuse, and into subgroups based on morphological, physiological characteristics. AG classifications are convenient and useful in identifying primary causal agents of Rhizoctonia diseases, although the mechanism of anastomosis is not fully understood. Beacause of the difficulties, we sought to develop a more direct method for genetic identification and charaterization of R. solani. Twenty nine isolates of R. solani were used for the analysis of genetic relationships among themselves and for rapid anastomosis grouping with AFLP method. All isolates studied were divided into five groups. Isolate 6 was included in AG-3 with 67% genetic similarity. When isolates 3 was compared with 13 and 10 each, they showed more than 84% and 83% similarity, respectively. Isolates 3, 4, 5, 13, and 16 were included in AG-1 with 83% genetic similarity. Isolates 1, 7, and 8 were included in AG-1(IB).

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