• Research in Plant Disease
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• v.21 no.1
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• pp.27-31
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• 2015

In April 2014, Fusarium wilt was found on kohlrabi seedlings in Iksan, Korea. Symptoms included wilting of foliage, drying and withering of older leaves, and stunting of the plants. The infected plants eventually died during growth. Colonies on potato dextrose agar were pinkish white, and felted with cottony and aerial mycelium. Macroconidia were falcate to almost straight, thin walled and usually 3-septate. Microconidia were usually formed abundantly in false-heads on short monophialides on the hyphae and were hyaline, smooth, oval to ellipsoidal, aseptate or medianly 1-septate, very occasionally 2-septate, slightly constricted at the septa, $4-11{\times}2.5-5{\mu}m$. On the basis of the morphological characteristics and phylogenetic analyses of molecular markers (internal transcribed spacer rDNA and translation elongation factor $1{\alpha}$), the fungus was identified as Fusarium oxysporum. Pathogenicity of a representative isolate was proved by artificial inoculation, fulfilling Koch's postulates. To our knowledge, this is the first report on the occurrence of Fusarium oxysporum on kohlrabi in Korea.

• Korean Journal of Organic Agriculture
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• v.24 no.1
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• pp.61-71
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• 2016

This study was carried out to investigate antimicrobial activities of water extracted Pleurotus ostreatus var Heuktari (PO), and their application to F. fujikuroi Nirenberg growth inhibition material. Various organic solvents (chloroform, hexane, ethyl acetate, ethanol) were tested to investigate the antimicrobial activities of Pleurotus ostreatus var Heuktari against F. fujikuroi Nirenberg. Chloroform, hexane, ethyl acetate and hot water extracts had no antimicrobial activities, but butanol extract showed 2.5% strong activities in order of F. fujikuroi Nirenberg disk diffusion test. Then we observe Antifungal activity using green house. Bed soil and mushroom extract mixed at 10%, 7.5%, 5%, 2.5%, 1% total bed soil mass. Screening of Antifungal activity was tested two periode 18day and 25day. The Antifungal activity rate of each period and extract density was 7.5% mixed bedsoil has investigated 80% Antifungal activity rate. The result indicates that the Pleurotus ostreatus var Heuktari extract using F. fujikuroi Nirenberg registance, which shows the development of organic agriculture seed disinfectant.

• Korean journal of applied entomology
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• v.18 no.1 s.38
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• pp.35-41
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• 1979

Four to $17\%$ of the seeds of ginseng (Panax ginseng Meyer) collected from seemingly healthy plants carried Colletotrichum panacicola Nakata et Takimoto whereas the seeds from the plants with anthracnose sympotoms carried $42\%$ of the same fungus. Prevalent organisms isolated other than C. panacicola from seeds of both kinds of plants were Fusarium, Alternaria, Phoma, Trichoderma and others, ana in that order on acidified potato sucrose agar. C. panacicola also was isolated from 18 months old herbarium specimens. The fungus in the infected tissues also survived during the Korean winter months either on the soil surface or in the soil at 10 and 30 em in depth. When conidial suspensions of C. panacicola were inoculated on detached ginseng leaves, anthracnose symptoms occurred from 25 to $35^{\circ}C$. No symptoms occurred at temperatures below $17^{\circ}C$. Direct sunlight increased significantly the number of anthracnose lesions over those obtained in leaves inoculated in darkness or in 400 lux of fluorescent light. The lesions decreased as age of the leaves increased or as the number of conidia applied decreased. Optimum temperature for mycelial growth and conidial formation of C. panacicola was $25^{\circ}C$. Optimum pH for the mycelial growth was at $pH\;2.8\~4.6$ while the most conidial formation occurred at $pH\;5.2\~5.8.$. When fungicides were applied in the field to ginseng plants with a conidial suspension of C. panacicola, the most effective control of the anthracnose disease was by spraying with difolatan, and followed by maneb, zineb, captan and phaltan; Bordeaux mixture and ferbam were significantly less effective but significantly better than the inoculated control plants.

• Research in Plant Disease
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• v.14 no.2
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• pp.107-111
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• 2008

For the eco-friendly control of fruit rot of fig, disease incidences according to the cultural practices at 51 fig orchards in south coast area of Korea were surveyed in 2002, and the effect of soil mulch and potassium phosphonate on fruit rot of fig was evaluated from 2002 to 2004. Diseased fruits of fig orchards of open field, rain shading, and vinyl house were 33.3%, 7.5%, and 0%, respectively. Diseased fruits were rated at 34.6%, 35.7%, and 27% as the tree spacing of $2m{\times}2m,\;2m{\times}3m,\;and\;3m{\times}4m$, respectively. Among the soil mulching materials, barley straw showed disease incidence of 1.8% and 3.5% of diseased fruits compared to 42.1% and 48% of no mulching in 2002 and 2003, respectively. Diseased fruits in dark paper film mulching were recorded at 4.8% and 12% in 2002 and 2003, respectively, which were lower than those in dark polyethylene film mulching at 11.2% and 26.2%. When potassium phosphonate(1,000 ppm) was sprayed 3 times with 10 days intervals from the beginning of disease occurrence, disease incidences were rated at 3.0% and 2.0% in 2003 and 2004, respectively, which were much lower than those of control at 45.9 % and 39.3%.

• Research in Plant Disease
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• v.22 no.4
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• pp.293-296
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• 2016

In late June 2016, stalk rot symptoms were observed on five vatieties of sorghum (Sorghum bicolar) at organic paddy-upland rotation system in Anseong city, Korea. The initial symptom on stalk surfaces was red color with a dark red spot lesion. A fungus was isolated from the initial lesion, and cultured on potato dextrose agar. Size of microconidia mostly extend to $5-19{\times}2-{\mu}m$ in culture, with 0-1 septa and macroconidia extend to $29-52{\times}3-4{\mu}m$ with 4-6 septa. Pathogenicity was investigated using conidial suspension spray to seedling of sorghum. After 3 days of inoculation, the dark red lesion was produced on stalks. On the basis of mycological characteristics, pathogenicity, and internal transcribed spacer (ITS) rDNA sequence analysis, this fungus was identified as Fusarium thapsinum. This is the first report of stalk rot on sorghum caused by F. thapsinum in Korea.

• Horticultural Science & Technology
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• v.31 no.4
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• pp.512-516
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• 2013

Pear cultivar 'Sinhwa' (Pyrus pyrifolia var. culta Nakai) was originated from a cross between 'Niitaka' and Whasan' with the aims of improving the fruit quality and the traits of cultivation and of early maturing more than 'Whasan' cultivar at Pear Research Station of National Institute of Horticultural & Herbal Science, Rural Development Administration in 1995. 'Sinhwa' was preliminarily selected in 2004 and named in 2009. The tree shows vigorous growth habit and semi-spread characters like 'Niitaka'. Furthermore, it has a sufficient and well upkeep of the flower bud, so it can be more easily cultivated in orchards. In the flower characteristics, flowering time of 'Sinhwa' is $11^{th}$ April like as maternal parent 'Niitaka'. Also 'Sinhwa' has short of pollen grains, so it is need above two pollinizer cultivars. 'Sinhwa' is highly resistant to black leaf spot (Alternaria kikuchiana) and relatively strong to pear scab (Venturia nashicola) in field condition. The optimum harvest time is around Sep. $15^{th}$ in Naju, which is ahead of 'Whasan' about 10 days in the harvest period. The fruit shape is oblate and fruit skin color is yellowish-brown during harvesting time. The average weight of fruit is 627 g, and the soluble solids content is $13.0^{\circ}Brix$. The flesh is very soft and juicy, and renders good eating quality. Shelf life is about 30 days under the room temperature condition.

• Research in Plant Disease
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• v.12 no.3
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• pp.226-230
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• 2006

Cucumber mosaic virus(CMV) was occurred on red pepper showing vein chlorosis or vein necrosis with the incidence rate of 52% from 62 specimens collected in natural fields. Among 32 samples infected with CMV, the specimens of 22 red pepper leaves showing vein chlorosis were infected singly with CMV-VCH. CMV-VCH induced vein chlorosis on the inoculated leaves, and vein banding and vein necrosis on the upper leaves of Nicotiana glutinosa, and then killed after showing bud necrosis. The typical symptoms of vein banding, malformation and blister were produced on the upper leaves of Nicotiana benthamiana and N. tabacum 'Ky-57' without symptoms on the inoculated leaves. The commercial cultivars of 'Bugang', 'Manitta' and 'Gwariput' were shown the typical symptom of vein chlorosis by the mechanical inoculation of CMV-VCH. CMV-VCH was detected specifically by RT-PCR. Virus particles of CMV-VCH were isometric shape having 30 nm diameter. Ultraviolet absorption of purified CMV-VCH was maximum at 260 nm and minimum at 242 nm. The ratio of A260/A280 was 1.71. CMV-VCH had the single nucleo-protein having the molecular weight of 24.5 kDa.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.32-37
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• 2007

The study was carried out to establish buffer zone for the protection of the non-target organisms by aerial pesticide application. The two pesticide combination of 3-way tank-mixing of three pesticides for aerial application, ferimzone tricyclazole SC + BPMC EC + validamycin-A SL and hexaconzole EC + isoprothiolane EC+phenthoate EC were selected for the simultaneous control of key pests on paddy rice as blast, sheath blight, brown planthopper and moth. Aquatic organisms including killifish and loach in the paddy field and nearby water reservoirs were not affected by aerial application of the pesticides. However, all the water flea were killed, when they were exposed 10 m from the aerially sprayed site, while the water flea exposed in 30 m away from the site were not affected. Honeybees within 50 m in the wind direction and 20 m in the opposite wind direction showed a mortality of $7{\sim}100%$. Residues concentration of the pesticides in paddy water were not detectable level after six days from aerial application. Drifting distance of aerially sprayed droplet from the target area was within 30 m in the wind direction and 20 m in the opposite direction. Consequently, it was the buffer zones in the aerial pesticides application for the protection of the non-target organisms should be at least 50 m for aquatic organisms and 100 m for honeybees.

• Research in Plant Disease
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• v.19 no.1
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• pp.45-48
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• 2013

Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales. Rusts can affect a variety of plants. Development of new effective and environmentally benign agents against rusts is of great interest. In this study, we investigated the disease control efficacy of the emulsion concentrate (EC10) and wettable powder (WP20) type formulations of the extract of Magnolia officinalis (Magjia90; containing honokiol and magnolol at 90%) against rust diseases of perilla and zoysiagrass in fields. The treatment of EC10 and WP20 of Magjia90 showed control values of 47.9% to 69.6% and Magjia90-WP20 reduced more effectively the development of rust symptoms on perilla plants than Magjia90-EC10. Magjia90-WP20 also highly suppressed zoysiagrass rust with control values of 65.7% to 80.5%. On the other hand, no harmful effect of Magjia90-EC10 and Magjia90-WP20 was observed on the perilla and zoysiagrass plants tested. The results strongly indicate that the extract of M. officinalis (Magjia90) can be used as a natural fungicide for the control of rust diseases.

• Research in Plant Disease
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• v.19 no.3
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• pp.229-232
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• 2013

Sclerotium rot of cucumber (Cucumis sativus L.) occurred at the experimental field of Gyeongsangnam-do Agricultural Research and Extension Services in July 2012. The typical symptoms included wilt, rot, and water-soaking on stems and fruits and severely infected plants eventually died. White mycelial mats spread over lesions, and then sclerotia were formed on fruit and near soil line. The sclerotia were globoid in shape, white to brown in color and 1-3 mm in size and the hyphal width was 4-8 ${\mu}m$. The optimum temperature for mycelial growth and sclerotia formation on PDA was $30^{\circ}C$. The typical clamp connections were observed in the hyphae of the fungus grown on PDA. For further identification, the complete internal transcribed spacer (ITS) rDNA region was amplified and sequenced. On the basis of mycological characteristics, ITS rDNA region comparison, and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report of sclerotium rot on cucumber caused by S. rolfsii in Korea.