• 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.

• Asian Journal of Turfgrass Science
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• v.9 no.3
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• pp.235-252
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• 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 $^{\circ}C$.

• Asian Journal of Turfgrass Science
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• v.24 no.1
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• pp.9-15
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• 2010

During 2008~2009 winter season, yellow patch and gray snow mold occurred on turfgrass plants in golf courses in Kangwon and Jeonbuk provinces, respectively. The fungi associated with the diseases were identified as Rhizoctonia cerealis Van der Hoeven and Typhlua incarnata Lasch ex Fr., based on the morphological characteristics of hyphae and sclerotia. R. cerealis and T. incarnata were pathogenic to most turfgrass and crop species tested. R. cerealis infected crown, stem and leaf tissue of the host plants, and the symptom was light yellow circular patch. Individual infected leaf near the margin of patch developed red color first and finally turn brown. The symptoms caused by gray snow mold pathogen are water-soaked spots, and became a watery soft rot. Infection parts became yellow and then turned brown followed by death of the whole plant. White mycelia were developed on higher petioles, leaves, and on soil where these plant parts lay, and black sclerotia of variable size and shape formed in the mycelial mass. All isolates tested were pathogenic on most turfgrass and crop plants, and significantly different in aggressiveness. Disease severity increased with longer snow cover days on target plants, suggesting that disease severity was expressed over snow cover days. There were significant differences in disease severity among the graminious species, and among cultivars within each species, indicating varying levels of susceptibility to R. cerealis and T. incarnata.

• 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.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.57-63
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• 2006

This study was carried out to investigate control efficacy of natural compound, TGR-N1 against turfgrass fungal diseases. TGR-N1 showed antimicrobial activity in vitro. Rhizoctonia solani AG 1-1, Rhizoctonia solani AG2-2, Rhizoctonia cerealis, Sclerotinia homoeocarpa and Colletotrichum graminicola were inhibited by 500 times and 1,000 times of diluents of TGR-N1. Pythium spp. was not inhibited by the same diluents of TGR-N1. The TGR-N1 also showed a remarkable antifungal activity against Rhizoctonia solani AG 1-1, Rhizoctonia solani AG2-2 in field. This study proved the antifungal activity of natural compound, TGR-N1 and showed its potential as a natural pesticide.

• Asian Journal of Turfgrass Science
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• v.24 no.1
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• pp.24-30
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• 2010

We investigated occurrence of yellow patch for early spring season of 48 cultivars in 5 species of turfgrass, most popularly used in Korea golf courses. Only yellow patch disease caused by Rhizoctonia cerealis was occurred naturally from late fall season. Perennial ryegrass and creeping bentgrass cultivars showed susceptibility from yellow patch in early spring, respectively. However, among There was no significantly different between the other species. Creeping bentgrass, 'Pennlinks II' cultivar was the most susceptible. Yellow patch symptom showed reddish brown with margins in color and patch showed size from 5 cm to 50 cm in diameter. Based on our results, Yellow patch showed large differences among cultivar and each turfgrass species.

• Asian Journal of Turfgrass Science
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• v.6 no.2
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• pp.99-111
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• 1992

Yellow patch as leaf blight caused by binucleate Rhizoctonia occured in bentgrass (Agrostis Palustris Huds), zoysiagrass (Zoysia japonica Steud) and Kentucky bluegrass (Poa pratensis L.) from several golf couses in Korea. Binucleate Rhizoctonia was isolated from the infected lesions and was identified Rhizoctonia cerealis. Rhizoctonia cerealis infected crown, stem and leaf tissue, and the symptom was light yellow circular patch upto 1 m in diameter on bentgrass golf green. Individual infected leaf near the margin of patch developed first red and finally turn brown. As zoysiagrass lawn, the symptom was 30~40cm circular patch that occured zoysiagrass shooting time as spring, and there could not sheeted in severe lesion. In case of sheeted, zoysiagrass was first irregular leaf sopt and finally dead. Hypha diameter of Rhizoctonia cerealis was $2.5~6.3\mu\textrm{m}$(average $3.8\mu\textrm{m}$) and colar was white to buff. Monilioid cell size was $5.8~12.5$\times$13.8~37.5\mu\textrm{m}$. Sclerotia size was 0.2~2.0mm and color was white to brown. Optium temperature for the hypha growth was $23^{\circ}C$. There was a little difference in pathogenicity among the isolates.

• Research in Plant Disease
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• v.17 no.1
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• pp.19-24
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• 2011

It was identified as a sharp eyespot (Rhizoctonia cerealis) that the isolates from abnormal symptoms in wheat that showed yellowing leaves, necrotic spot on stem base and dead tillers. These isolates have slower growth property and fewer mycelia than Rhizoctonia solani AG-1(1A) (KACC 40106). They showed binuclear cell, same media cultural and DNA characteristics to R. cerealis. They caused same symptoms on leaves and stem base appeared in artificial inoculation test, comparing to diseased wheat fields and also affect to maturing of kernels. They have optimal growth temperature and acidity on the artificial media as $20{\sim}25^{\circ}C$ and pH 5~7, respectively. In the investigation of varietal resistance of Korean winter cereal crops to sharp eyespot, there was no resistant in wheat cultivars that all materials infected over 20% diseased ratio. 12 cultivars including 'Anbaekmil', however, considered to moderate resistance with 20 to 30% infection ratio. The others crops using in feeding, whole crop barley, oat, rye and triticale were resistant below 15% diseased degree except the rye that showed over 50% infection rate. It was the first evaluation to sharp eyespot resistance for the Korean feeding crop cultivars. Most tested Korean barley cultivars for malting and food were moderate and susceptible to the sharp eyespot. Only 3 hulled barley, 'Tapgolbori', 'Albori' and 'Seodunchalbori', showed resistance with less than 10% diseased ratio. All tested naked barley cultivars showed susceptible response to the disease.

• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.213-218
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• 2017

The objective was to examine the antifungal activity of Pinus densiflora extract for the control of turfgrass fungal diseases. Antifungal activities of the various fractions of n-hexane, methylene chloride (Ch), ethyl acetate (EtOAc), and n-butanol from P. densiflora were evaluated against Rhizoctonia solani AG1-1B, R. solani AG2-2IV, Sclerotinia homoeocarpa, R. cerealis, Pythium spp., and Colletotrichum graminicola. The Ch and EtOAc fractions showed antifungal activity against Pythium sp. and C. graminicola in paper disc assay. The effective concentration to produce 50% mycelial inhibition ($EC_{50}$) using five discriminatory concentrations of pinosylvin (1) from the Ch fraction of P. densiflora was evaluated on R. solani AG1-1B, R. solani AG2-2IV, R. cerealis, and S. homoeocarpa. S. homoeocarpa showed the highest sensitivity with the lowest mean $EC_{50}$ value ($8.426{\mu}g/mL$) among the four pathogens. Among the three Rhizoctonia pathogens, R. cerealis had the highest mean $EC_{50}$ value ($99.832{\mu}g/mL$) and R. solani AG2-2IV, with the lowest sensitivity, had the lowest $EC_{50}$ value ($39.696{\mu}g/mL$). These results suggested that pinosylvin (1) from P. densiflora could be a valuable lead compound in the improvement of a novel antifungal agent.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.209-218
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• 2009

Bacterial isolates collected from rhizosphere of turfgrass showed strong in vitro antagonistic activities against a number of turfgrass soilborne pathogens such as Rhizoctonia cerealis, R. solani AG-1(1B), Sclerotinia homoeocarpa and Typhula incarnata. In vivo study, four bacterial isolates selected have control values over 60% against one or more turfgrass pathogenic fungi. The antagonistic effects of the bacterial isolates varied depending on fungal species, host plant, and disease pressure, indicating that control effects of the antagonists could be variable depending on field conditions. They were classified as belonging to the genus Pseudomonas species, based on morphological and biochemical characteristics as well as 16S rRNA analysis. The four bacterial isolates are under a study for finding proper cultural conditions and determination formulation type.