• The Korean Journal of Mycology
• /
• v.49 no.1
• /
• pp.133-137
• /
• 2021

Foot rot symptoms were occasionally observed on young bok choy (Brassica rapa subsp. chinensis) and kale (B. oleracea var. viridis) plants grown in vinyl greenhouses located in Icheon and Yangpyeong, Gyeonggi Province, Korea. These observations were made during disease surveys in April 2020. The incidence of diseased plants in the vinyl greenhouses investigated was 0.5-1.0% in bok choy and 0.5-5.0% in kale. Five isolates of Rhizoctonia sp. were obtained from diseased roots of bok choy and three isolates of Rhizoctonia sp. were taken from diseased stems of kale. All the Rhizoctonia sp. isolates were identified as Rhizoctonia solani AG-2-1 based on the morphological characteristics and anastomosis test. Three isolates each of R. solani AG-2-1 from bok choy and kale were tested for pathogenicity in their host plants by artificial inoculation. The tested isolates induced foot rot symptoms on the inoculated bok choy and kale plants. The symptoms on the bok choy and kale, induced by the artificial inoculation, were similar to those observed on plants from the vinyl greenhouses that were investigated. This is the first report of R. solani AG-2-1 causing foot rot in bok choy and kale in Korea.

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

• The Korean Journal of Mycology
• /
• v.51 no.2
• /
• pp.141-146
• /
• 2023

Stem rot symptoms were observed in Gondre (Cirsium setidens) plants growing in a vinyl greenhouse in Taebaek, Korea during a disease survey in June 2022. The plants presented with dark brown to black rot on the stems at or above the soil line. Severely diseased plants displayed wilt and blight. Disease incidence among these plants ranged from 1 to 5%. Three isolates of Rhizoctonia sp. were obtained from the stem lesions of diseased plants. All isolates were identified as Rhizoctonia solani AG-2-2(IV) based on the morphological and cultural characteristics, results of the anastomosis test, and phylogenetic analysis. The pathogenicity of the isolates to Gondre plants was confirmed using an artificial inoculation test. The lesions induced by the inoculation test were similar to those observed in the investigated vinyl greenhouse. Here, we report a case of R. solani AG-2-2(IV) causing stem rot in Gondre.

• The Korean Journal of Mycology
• /
• v.49 no.3
• /
• pp.413-416
• /
• 2021

In July 2019, damping-off symptoms of young Fischer's ragwort (Ligularia fischeri) plants were observed in four vinyl greenhouses of a farmer located in Taebaek, Gangwon Province, Korea. This disease occurred in 20-30% of plants in the vinyl greenhouses investigated. Nine isolates of Rhizoctonia sp. were obtained from the diseased plants. All the isolates were identified as Rhizoctonia solani AG-2-2 (IIIB), based on morphological, cultural characteristics, and anastomosis test. Three isolates were used for artificial inoculation test on Fischer's ragwort. Pathogenicity of these isolates was confirmed on the plants with the inoculation tests. Damping-off symptoms observed on the inoculated plants were similar to those observed in the diseased plants in the vinyl greenhouses. This is the first report of R. solani AG-2-2 (IIIB) being the causative agent in damping-off in Fischer's ragwort.

• Asian Journal of Turfgrass Science
• /
• v.9 no.3
• /
• pp.235-252
• /
• 1995

Turfgrass Rhizoctonia blight is a severe disease in golf courses in Korea. Attempts were made in 1989 to 1994 to identify the Rhizoctonia species associated with turfgrass blights and also to examine their epidemiology. A total of 120 Rhizoctonia isolates collected were identified as R. solani AG1, R. solani AG2-2, R. cerealis(AG-D) and R. oryzas from brown patch, large patch, yellow patch and white patch, re-spectively. R. solani AG1 was mostly associated with brown patch of cool-season grasses. and most frequently isolated in June through July and also in September. R. solani AG2-2 was isolated exclusively from zoysiagrasses from April to November, most frequently in June through July and October through November. R. cerealis was isolated frequently from both creeping hentgrass in March through April and in November, and zoysiagrass in April and July. Thermophilic R. oryzae was isolated only from creeping bentgrass in August, although with very low frequency. R. solani AG2-2 was strongly pathogenic specifically to Korean lawngrasses(Zoysia japonica, Z.matrella, Z. tenuifolia), but non-pathogenic to creeping bentgrass(Agrostis palustris), bermudagrass (Cynodon dactylon), Kentucky bluegrass(Poa pratensis), perennial ryegrass(Lolium prenne), and creeping red fescue(Festuca rubra subsp. ruhra L.). R. cerealis was strongly pathogenic to zoysiagrass and bentgrass only, but was isolate-specific i.e., from non-pathogenic to pathogenic, for other turfgrasses. The mycelial growth was optimum at relatively high temperature ranges of 25~30$^{\circ}C$ for R.solani AG1, AG2-2 and R. oryzae, while the mycelial growth of R. cerealis was initiated at $^{\circ}C$ and almost ceased at or above $^{\circ}C$.

• Korean Journal Plant Pathology
• /
• v.11 no.3
• /
• pp.278-281
• /
• 1995

An isolate of Rhizoctonia solani AG 2-2(IV) from zoysiagrass was examined on development of its teleomorph by the modified soil-on-agar culture method. The most effective growth medium for sporulation was Czapek's 1/2 agar medium added with yeast extract and peptone. The characters of teleomorph of R. solani AG 2-2 (IV) are as follows. Hymenia developed on soil surface after the development of vegetative hyphae. Basidia were barrel-shaped, short clavate or obovate and were 11.4~17.9$\times$7.1~11.4 ${\mu}{\textrm}{m}$ (mean : 15.1$\times$9.0 ${\mu}{\textrm}{m}$) in size. Sterigmata were horn-shaped and slightly bent to the inner side and 4.3~18.6 ${\mu}{\textrm}{m}$ (mean : 10.3 ${\mu}{\textrm}{m}$) in size. Two to four sterigmata developed on each basidium. Basidiospores were obovate, ellipsoid to oblong-ellipsoid, hyaline, smooth, thin walled, with an apiculus, and 3.6~10.4$\times$2.9~5.7 ${\mu}{\textrm}{m}$ (mean : 7.8$\times$4.4 ${\mu}{\textrm}{m}$) in size.

• Asian Journal of Turfgrass Science
• /
• v.13 no.3
• /
• pp.131-138
• /
• 1999

A synergistic effect of biocontrol agent and chemicals on control of the large patch on turfgrass caused by Rhizoctonia solani AG2-2 was evaluated. Chemicals; mepronil, toclofos-methyl and iprodione inhibited 90∼100% mycelial growth of R. solani AG1 and AG2-2 in vitro. While on the other, the chemicals inhibited only 0∼5%, 18∼46% and 30∼67% of mycelial growth of the antagonists, respectively. In field application, toclofos-methyl was the best to suppress the disease in single application, however, the combination of mepronil and T. viride 41D showed highest disease control effect among combinations of antagonists and chemicals. Effect of the combination of mepronil and T. viride 41D was similar to that of toclofos-methyl and T. viride 41D stage of disease development, but became higher in six week late. Results indicated that the combined application of selected antagonistic agent and chemical increased control efficasy of turgrass large patch.

• Mycobiology
• /
• v.49 no.2
• /
• pp.196-200
• /
• 2021

In May to July 2019, ovate-leaf atractylodes seedling and plant with Damping-off symptoms were observed in farmer field at Sangju and Mungyeong, Korea. Seven fungal isolates have been retrieved from diseased root tissue and identified as Rhizoctonia solani AG-5 based on morphological and molecular characteristics. To the best of our knowledge, this is the first report on damping-off of ovate-leaf atractylodes caused by R. solani AG-5 in South Korea.

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

• The Korean Journal of Mycology
• /
• v.50 no.1
• /
• pp.61-64
• /
• 2022

In July and September 2020, a severe outbreak of stem rot was observed on bonnet bellflower (Codonopsis lanceolata) plants in a farm located in Chuncheon, Gangwon Province, Korea. The symptoms initially appeared on the stem at or above the soil line. Later, the infected stem completely rotted and blighted. The incidence of diseased plants in the field was 2-30%. Ten isolates of Rhizoctonia sp. were obtained from the stem lesions of diseased plants. All isolates were identified as Rhizoctonia solani AG-4 based on the morphological characteristics and anastomosis test. Three isolates of R. solani AG-4 were tested for pathogenicity on bonnet bellflower plants through artificial inoculation. All tested isolates induced stem rot symptoms on the inoculated plants. The symptoms were similar to those observed in plants from the farm. This is the first report of R. solani AG-4 causing stem rot in bonnet bellflower.