• Weed & Turfgrass Science
• /
• v.2 no.1
• /
• pp.70-75
• /
• 2013

Seven medicinal plant extracts were tested for antifungal activities against six species of the major turfgrass pathogenic fungi (Colletotrichum graminicola, Pythium spp., Rhizoctonia cerealis, Rhizoctonia solani AG1-1, Rhizoctonia solani AG2-2, and Sclerotinia homoeocarpa) using paper disk diffusion method. Three medicinal plant extracts, including Pinus densiflora showed antifungal activities. In suppression of mycelium growth test, on medium adding P. densiflora extract showed that inhibition rate of mycelium growth were above 80% in 10 mg/10 ml concentration of the extract. The inhibition rate of Pythium spp. was 100% and C. graminicola was 84.3% in 10 mg/10 ml concentrations of P. densiflora extract, respectively. In particularly, the inhibition rate of Pythium spp. was 89.5% in 2 mg/10 ml concentrations of P. densiflora extract. As a result, P. densiflora extract showed high antifungal activity to Pythium spp. and C. graminicola of the turfgrass pathogen in in vitro test.

• 한국균학회소식:학술대회논문집
• /
• 2015.05a
• /
• pp.55-55
• /
• 2015

Rust is one of the most destructive diseases on economically important plants such as agricultural and horticultural crops, as well as forest trees [1]. Chemical treatment is the most effective means to control rust, but use of the chemical fungicides involves inevitable risks to human health and environment [2]. Unfortunately, biocontrol is currently impracticable for rust disease management [3]. It is necessary to exploit biocontrol agents to help prevent rust diseases. As a fundamental research for future development of biocontrol agents for rusts, biodiversity of hyperparasites occurring on rust fungi was investigated. During 2006-2010, 197 fungal isolates of the rust hyperparasites were collected and isolated from various combinations of mycohosts and plant hosts in many regions of Korea. Based on morphological and molecular data, they were identified as 8 genera and 12 species. Besides, phylogenetic relationships between the hyperparasites and related taxa were inferred. A total of 114 isolates of Pseudovirgaria were obtained from rust pustules of Phragmidium spp. and Pucciniastrum agrimoniae infecting rosaceous plants. Phylogenetic analysis using multigene sequences revealed a high level of genetic variability among many isolates of Pseudovirgaria and close correlation between the isolates and mycohosts. Only two species of Pseudovirgaria, P. hyperparasitica and P. grisea are often difficult to distinguish by their morphological similarity, but on the molecular basis they were clearly differentiated from each other. There had been no previous record of P. grisea outside Europe, but the present study has proved its presence in Korea. Among six distinct groups (five of P. hyperparasitica and one of P. grisea) within the Pseudovirgaria isolates, each lineage of P. hyperparasitica was closely associated with specific mycohosts and thus might have cospeciated with their mycohosts, which probably led to coevolution. Although P. grisea possesses a host preference for Phragmidium species occurring on Rubus, it was not specific for a mycohost. P. grisea seems to evolve in the direction of having a broad mycohost range. Seventeen isolates of Verticillium-like fungi were isolated from rust sori. Based on morphological data and DNA sequence analysis, the isolates were identified as three Lecanicillium species, viz. L. attenuatum, Lecanicillium sp. 1, Lecanicillium sp. 2, and V. epiphytum. The unidenified two species of Lecanicillium appear to be previously unknown taxa. Sixty-six isolates of miscellaneous hyphomycetes belonging to 6 species of 5 genera were obtained from pustules of rust fungi. On the basis of morphological and molecular analyses, the miscellaneous hyphomycetes growing on rusts were identified as Acrodontium crateriforme, Cladophialophora pucciniophila, Cladosporium cladosporioides, Phacellium vossianum, Ramularia coleosporii, and R. uredinicola.

• Research in Plant Disease
• /
• v.18 no.4
• /
• pp.310-316
• /
• 2012

Gibberellea fujikuroi species (Gf) complex comprises at least 15 species, most of which not only causes serious plant diseases, but also produces mycotoxins including fumonisins. Here, we focused on the abilities of the field isolates belonging to the Gf complex associated with rice and corn, respectively in Korea to produce fumonisin, all of which were confirmed to carry FUM1, the polyketide synthase gene essential for fumonisin biosynthesis. A total of 88 Gf complex isolates (55 F. fujikuroi, 10 F. verticillioides, 20 F. proliferatum, 2 F. subglutinans, and 1 F. concentricum), and 4 isolates of F. commune, which is a non-member of Gf complex, were grown on rice substrate and determined for their production levels of fumonisins by a HPLC method. Most isolates of F. verticillioides and F. proliferatum, regardless of host origins, produced fumonisin $B_1$ and $B_2$ at diverse ranges of levels ($0.5-2,686.4{\mu}g/g$, and $0.7-1,497.6{\mu}g/g$, respectively). In contrast, all the isolates of F. fujikuroi and other Fusarium species examined produced no fumonisins or only trace amounts ($<10{\mu}g/g$) of fumonisins. Interestingly, the frequencies of relatively high fumonisin-producers among the F. proliferatum and F. fujikuroi isolates derived from corn were higher than those among the fungal isolates from rice. In addition, it is a first report demonstrating the ability of the FUM1-carrying F. commune isolates from rice to produce fumonisins.

• Journal of Life Science
• /
• v.18 no.7
• /
• pp.974-979
• /
• 2008

The powdery mildew, a fungal plant disease found in varieties of plant cultures, is occurred by attack with Fusarium sp., Sphaerotheca sp., Leveilluna sp., and Eryshipe sp.. In this study we investigated the control of Fusarium graminearum, a barley powdery mildew fungus, by natural plant extracts. Among the 900 plant extracts tested, Zanthoxylum schinifolium, Ligusticum acutilobum, Bidens frondosa L., Dictamnus dasycarpus, Evodia officinalis, Disporum sessile, Scopolia japonica Max., Styrax japonica S. et Z., Dictamnus dasycarpus Turcz., Sinomenium acutum Rehder et Wils., Eugenia aromaticum, Rubus parvifolius L., Reynoutria elliptica, Coptis chinensis, Paeonia lactiflora Pall., Rheum undalatum, Paeonia suffruticosa, Oenothera odorata Jacq., Euphorbia pekinensis Rupr., and Nepeta cataria were selected based on spore germination inhibition assay. Further mycelial growth inhibition assay with economical and safety considerations led us to finally select Z. schinifolium (sancho) for control of F. graminearum. To produce antifungal sancho extract, methanol was suitable for extraction and subsequent fractionations of the extract showed that the water residue mainly had antifungal activity. The sancho extract and its fractions showed minor antibacterial activity against different pathogenic or food spoilage bacteria, but they did not show any harmful effects against young tomato plant by treatment of $1,000\;{\mu}g/ml$ in green chamber test. These results suggested that the extract of sancho has high potentials on control of a powdery mildew fungus, F. graminearum.

• Research in Plant Disease
• /
• v.23 no.3
• /
• pp.256-261
• /
• 2017

The effects of insecticide and fungicide treatment were investigated to reduce mycotoxin contamination of corn (Zea mays L.) seeds. Deoxynivalenol and zearalenone contents were reduced in the treated seeds, but aflatoxin, ochratoxin A, fumonisin, and T-2 toxin were not effective by chemical treatments. The chemical treatment did not affect the growth of saprophyte, but inhibited the pathogenic fungi such as Fusarium verticillioides, F. graminearum and F. equiseti. Myotoxin contents at different harvesting time were compared. As the harvest time was delayed, both levels of deoxynivalenol and zearalenone and frequency of Fusarium spp. increased. However, the major nutrient contents of corn seeds were not affected by harvesting period. These results show that chemical treatments are necessary to reduce the fungal contamination of corn and harvest without delay is important as well.

• Research in Plant Disease
• /
• v.23 no.4
• /
• pp.367-371
• /
• 2017

In 2015, symptoms of die-back on Rosa hybrida were observed in Taean, Korea. The aims of this study were to determine the cause of die-back on Rosa hybrida and characterize the pathogen. The fungal isolates were obtained and used for pathogenicity test, morphological and molecular analyses. The pathogenicity test on healthy branches of Rosa hybrida produced die-back, as the original symptoms. For the morphological study, the isolates were inoculated onto potato dextrose agar and incubated for 7 days at $25^{\circ}C$. The colonies grew up quickly and turned white to gray in color. Conidia were observed under an optical microscope. The features of conidia were ellipsoidal, grayish brown in color, $20-31{\times}11-17{\mu}m$ in size and had one septum. Molecular analyses of the ITS region, TEF and TUB genes were conducted to confirm the identity of the pathogen. The phylogenetic tree of the multi-gene sequences indicated that the causal agent was Lasiodiplodia pseudotheobromae. This study is the first report of die-back caused by Lasiodiplodia pseudotheobromae on Rose (Rosa hybrida).

• The Korean Journal of Mycology
• /
• v.14 no.2
• /
• pp.109-119
• /
• 1986

The correlations between environmental influences on microorganisms in soil and its effects on disease development in ginseng field were studied to obtain some useful data for increasing ginseng production and effective preventive measures against the root rot caused by soil-borne pathogens. The diseased replanted ginseng fields were selected as the diseased field and the healthy plot in first planted field selected as control in three major Korean ginseng producing areas such as Kumsan, Goesan and Poonggi. The physicochemical characteristics of the soil were analyzed and microorganisms susceptible for root rot of ginseng, such as Fusarium spp. and general fungi were investigated for their population density in various soil conditions. Correlations between soil microbial populations and environmental factors were investigated. The numbers of Fusarium spp. propagules were abundant in fall in both soil conditions. The numbers of Fusarium spp. were 1.9 to 2.6 times higher in replanted field than first planted field except Goesan area. Relative ratio of Fusarium spp. to total fungi propagules in replanted field was 1.6 times higher in replanted field than first planted field indicating higher numbers of Fusarium spp. distributed in replanted field of soil. The numbers of propagules of total fungi were increased in June and July and there was no sensitive variation according to the temperature. There was no significant difference in vertical distributions of total fungi according to soil depth, while the total fungi were abundant in the surface layer and $10{\sim}15\;cm$ layer. The contents of organic matter and phosphate in healthy field were somewhat high, and phosphate/organic matter ratio and Mg contents were high in diseased field. All of the soils showed a weak acidic pH of 4.5 to 5.7. Soil moisture contents were increased during winter season, but did not show any significant changes during the growing periods, showing 24.6% in healthy field and 19.5% in diseased field respectively. Soil temperature was the highest in July and August and the lowest in January and February.

• Journal of Mushroom
• /
• v.13 no.2
• /
• pp.145-150
• /
• 2015

Mushroom sciarid fly Lycoriella ingenua (Dufour), syn. L. mali (Fitch) is one of the most common fly pests affecting the mushroom cultivation in Korea. This study was carried out to investigate the development at different temperatures and damages of L. ingenua in A. bisporus mushroom cultivation. Rearing of mushroom flies were carried out on mycelial culture in Petri dishes. The development of L. ingenua from egg to adult at the temperature of 16, 20, 24, $28^{\circ}C$ were 35.2, 25.8, 23.5, and 22.2 days, respectively. Adult flies invade mushroom farms and oviposit in freshly spawned compost. Damages are mainly caused by the larvae of 1-7 mm, which feed on growing mycelium and also developing stipes and caps of mushrooms. Adult flies spoil the appearance of the fruiting bodies, spread various fungal and bacterial disease, and transmit mites. The damages by mushroom flies increased without pest control causing yield loss of up to 27%.

• Research in Plant Disease
• /
• v.18 no.3
• /
• pp.217-224
• /
• 2012

Post-harvest rot of grape causes a severe economic loss and lower of the grape quality. It is also one of the important limiting factors for grape export. Grape rots and their casual agents on 'Red Globe' variety imported from Chile were identified. Grapes shown rotting symptom were collected from the storages near the import harbor. The 3 different rots were identified on the imported 'Red Globe'; melting decay, gray mold, and blue mold. A bacterium that isolated from a typical melting decay symptom was identified as Gluconobacter cerinus on basis of its nucleotide sequence of 16S rDNA and fatty acid profile. By inoculation on grape, it caused cracking and dissolution of epidermis of grape which were the characteristics of melting decay. Botrytis cinerea and Penicillium expansum were isolated from grapes showing gray mold and blue mold. The 2 fungal isolates were identified on basis of their morphological characteristics and nucleotide sequence of their beta-tubulin genes. They showed strong pathogenicity on 'Campbell Early' variety that is a major table grape in Korea.

• Journal of fish pathology
• /
• v.20 no.2
• /
• pp.147-160
• /
• 2007

Four strains of water mold, ChS-E0511, RaT-E0511, RaT-A0512 and MaS-F0512, were isolated from salmonid fish and/or their eggs taken from culture farms in Yangyang, Milyang and Pyeongchang, Korea in 2005. Descriptions of their morphological aspects, the results of the phylogenetic analysis conducted, and the sequence of the small sub-unit 18S rRNAs of the isolates confirmed that they all belong to the species Saprolegnia parasitica. Only one species, ChS-E0511, which was isolated from fertilized eggs of the chum salmon, was classified as part of the S. parasiticaGroup 1 according to its oogonia and gemmae production. The chemotherapeutic effects of various chemicals on the ChS-E0511 strain were assessed from the inhibitory effects of growth in GY media and the relative ratio of eyed eggs to fertilized eggs of the rainbow trout. Malchite green, a prohibited substance in food animals, was better than others, such as the Opuntia ficus-indicaextract, 2-bronopol, and sodium chloride. These results suggest that the fungi isolated from salmonids and/or their eggs identified as S. parasitica were composed of more than two groups. These isolates will be useful in an intensive evaluation of therapeutic agents.