• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.4
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• pp.305-311
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• 1993

Although corn (Zea mays L.) hybrids are now widely grown as a silage crop in Korea, but agronomic data and silage quality of the corn hybrids produced from farmer's fields have not been published. Therefore, a research survey assessing forage yield and quality of the corn hybrids was conducted at 8 and 13 dairy farms in 1988 and 1989, respectively. in Yoju and Ichon. Kyeongi Province. In 1988, percent ear bearing plants, plant population, ear/total dry matter ratio. percent dry matter and dry matter yield of corn hybrids were 75.3%, 75,826 plants/ha, 38.3%, 23.8% and 12,661 kg/ha. respectively. compared with corresponding values of 79.5%. 79,981 plants/ha, 41.1%. 20.7% and 16.152 kg/ha in 1989, but 11.9% of rice black streaked dwarf virus (RBSDV) was recorded in 1989. The Flieg's score of corn silage made by dairy farmers ranged from 70 to 100 and averaged 91. The corn silage produced from dairy farms was characterized as a high quality grade. Survey data indicated that late maturing types of corn hybrids with a higher plant population were grown at farmer's fields. As a result, the performances of the corn hybrids produced by farmers were much lower than those of research institutes. Therefore, dairy farmers in the mid-northern regions of Korea should grow more early maturing corn hybrids and use much lower plant population than those of the present.

• Research in Plant Disease
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• v.10 no.4
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• pp.248-259
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• 2004

A total 115 isolates of Fusarium species from ginseng roots of 'rotted', and soils collected during 1982-1985 in Korea, were identified and classified into 11 species with the Snyder & Hansen System (with reference to Gerlach-Nirenberg's Modified System). The most dominant of these species were F. solani (55 isolates), F. oxysporum (35 isolates), and F. moniliforme (10 isolates) sensu Snyder & Hansen. The other 8 species (15 isolates) were very rarely isolated and previously identified as F. roseum sensu Snyder & Hansen (1945); these were F. equiseti, F. avenaceum, F. graminum, F. arthrosporioides, F. sambucinum, F. reticulatum, F. semitectum and F. poa. Tested for the ability to infect the roots of ginseng (3 yr. old plants) in field condition with the mycelial inoculum, only one isolate of F. solani (34 isolates tested) and one isolate of F. oxysporum (24 isolates tested) were weakly pathogenic to ginseng roots. Any of the isolates (7 isolates tested) of F. moniliforme [Liseola section] were not pathogenic to ginseng. However, all the isolates of tested of the species of Phytophthora cactorum, Pythium ultimum, and Cylindrocarpon destructans were highly pathogenic to ginseng roots. The species of Fusarium solani and Cylindrocarpon destructans were supposed to be a host dominant disease agent in ginseng plant.

• Research in Plant Disease
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• v.17 no.3
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• pp.358-363
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• 2011

Dapple fruits of plum cv. Oiishiwase (Prunus salicina L.) were occurred at Gyeonggi-do and Gyeongsangbukdo. The symptoms resembled the dapple fruit disease caused by Hop stunt viroid (HSVd). To identify the causal disease agents, RT-PCR was performed with the specific primers of HSVd. RT-PCR analysis showed that HSVd variants (DP1, DP2) were detected from dapple fruits. HSVd detection was also confirmed by the dot blot hybridization using a DIG-probe specific to HSVd. Nucleotide sequences of DP1 and DP2 had the identities of 94-100% with those of other 7 variants of HSVd in Genbank database. DP1 and DP2 were different in two nucleotides of CG and AA at position of 59 and 60, orderly. Based on nucleotide sequences at position of 59 and 60, HSVd variants associated with plum dapple fruits could be divided mainly into three groups as CG, AA and TG.

• Research in Plant Disease
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• v.23 no.3
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• pp.241-248
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• 2017

The purpose of this study was to develop rapid methods for distinguishing between Heterodera schachtii and H. glycines detected from chinese cabbage fields of highland in Gangwon, Korea. To do this, we performed PCR-RFLP and PCR with the primers set developed in this study for GC147, GC408 and PM001 population, H. schachtii, and YS224, DA142 and BC115 population, H. glycines. Eight restriction enzymes generated RFLP profiles of mtDNA COI region for populations of H. schachtii and H. glycines, repectively. As a result, treatment of two restriction enzymes, RsaI and HinfI, were allowed to distinguish H. schachtii from H. glycines based on the differences of DNA band patterns. The primer set, #JBS1, #JBG1 and #JB3R, amplified specific fragments with 277 and 339 bp of H. schachtii, 339 bp of H. glycines, respectively, while it did not amplify fragments from three root-knot nematodes and two root-lesion nematodes. Thus, the primer set developed in this study could be a good method, which is used to distinguish between H. schachtii and H. glycines.

• Research in Plant Disease
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• v.23 no.4
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• pp.348-354
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• 2017

To investigate occurrence of root-knot nematode (RKN) in plastic house of central area of Korea, 132 soil samples were collected in cucumber, water melon, tomato, red pepper and strawberry fields from 2013 to 2015. Among 132 soil samples, 65 soil samples (49%) were infested with RKN and mean density of RKN was 178 second-stage juveniles per $100cm^3$ soil (min. 1 ~ max. 3,947). The frequency of RKN by regional was the highest in Chuncheon with 80%, followed by Cheonan (68%), Nonsan (36%), Buyeo (33%) and Yesan (30%). The frequency of RKN by crops was the highest in tomato with 83%, followed by cucumber (61%), strawberry (41%), red pepper (30%), watermelon (26%). To identify the species of RKN, fifteen populations were selected for representative populations. As a phylogenetic analysis of 15 populations, southern root-knot nematode (Meloidogyne incognita), peanut root-knot nematode (M. arenaria) and northern root-knot nematode (M. hapla) were identified with 47%, 20% and 33% ratio, respectively. In crops, M. incognita, M. arenaria and M. hapla were detected in tomato, M. incognita and M. arenaria were detected in cucumber and watermelon, and M. hapla was detected in strawberry and lettuce. Thus, there should be a continuous management to major species of each crops to prevent dispersal of RKN damages.

• The Korean Journal of Mycology
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• v.45 no.3
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• pp.246-250
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• 2017

Sclerotium rot was observed on mungbean (Phaseolus radiatus L.) plants cultivated in the exhibition field of Gyeongsangnam-do Agricultural Research and Extension Services in September 2015. The progression of rot was initially observed as water-soaked lesions on several parts of the affected plant. Severely infected plants were blighted and eventually died. White mycelial mats spread over the lesions and numerous sclerotia formed on stems near the soil line. The sclerotia were globoid in shape, 1~3 mm in size, and white to brown in color. The optimum temperature for mycelial growth and sclerotia formation on potato dextrose agar (PDA) was $30^{\circ}C$ and the hyphal width was $4{\sim}8{\mu}m$. Typical clamp connections were observed on the hyphae of fungus grown on PDA. For molecular identification, the complete internal transcribed spacer (ITS) ribosomal DNA (rDNA) of the causal fungus was sequenced and analyzed. Based on the mycological characteristics, ITS rDNA sequence analysis, and pathogenicity to host plants, the fungus was identified as Sclerotium rolfsii. This is the first report of Sclerotium rot on mungbean caused by S. rolfsii in Korea.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.151-158
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• 1997

Tomato (lycopersicon esculentum Mill.‘Sunroad’) seedlings grafted onto the four different rootstocks, ‘Anchor-T’, ‘Kagemushia’, ‘Joint’ and ‘Vulcan’, and fed with different amount of nitrogen were investigated for their susceptibility to the root rot Fusarium wilt (Fusarium oxysporum Schl. f. sp. lycopersici Snyder et Hansen, race J$_3$) disease, plant growth, and fruit quality. The flowering of the first flower cluster was promoted in grafted plants (GP) as compared to non-grafted (NG) ones. The plant height was increased by the grafting, and the growth and stem diameter were enhanced with increased nitrogen levels. Grafted plants were little affected by the Fusarium wilt disease except ‘Anchor-T’rootstock (64.7％ infection). The rate of malformed, underdeveloped, and gray-mold infected fruits were reduced in the grafted plants regardless of the rootstocks. Soluble solid content, sugars, ascorbic acids and organic acids did not show any difference between grafted and non grafted plants, but ascorbic acid tends to be reduced in the high nitrogen treatment. Content of N, Ca and Mg in leaves were greatly increased in the GP grown with high nitrogen level (30kg.㏊$^{-1}$ ).

• Research in Plant Disease
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• v.21 no.4
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• pp.337-340
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• 2015

During July to November 2014, severe rust infection was consistently found on Peucedanum japonicum growing farm in Yeosu, Korea. The rust was observed mainly on lower leaf surfaces. Symptoms of typical plants included yellow-orange rust pustules were observed on the petiole and leaf surface with small yellowish to chlorotic lesions on the upper surface. No symptom was observed on flowers. Uredinia were occurred amphigenous on leaf surface, and occasionally caulicolous, scattered or loosely aggregate, rounded to oblong, 0.4 to 4 mm in diameter, covered by epidermis, then naked, surrounded by ruptured epidermis, pulverulent, and brown. Urediniospores were ovate-ellipsoid, ellipsoid or subglobose, light brown, 20 to $45{\times}15$ to $35{\mu}m$, walls 2 to $4{\mu}m$ thick. The resulting sequences were deposited in GenBank with accession No. KT778808, KT778809, and KT778810, respectively. Since this was the first accession of 28S sequence Puccinia jogashimensis, there was no exact match in GenBank nucleotide database. On the basis of the morphological characteristics and phylogenetic analyses of 28S rDNA, the fungus was identified as P. jogashimensis. To our knowledge, this is the first confirmed report on the occurrence of P. jogashimensis on P. japonicum in Korea.

• Research in Plant Disease
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• v.21 no.1
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• pp.36-39
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• 2015

In June 2012 and 2013, a destructive stem rot symptoms of Ligularia fischeri occurred sporadically in Hoengseong-gun and Pyeongchang-gun Gangwon-do, Korea. The typical symptom included water-soaking on the main stem, rotting, wilting and blighting, which eventually leads to death of the plant. White mycelial mats were spread over lesions and brown sclerotia were formed on stems and near soil surface. The sclerotia were white to brown, spherical or irregular, 1-3 mm in size on potato dextrose agar (PDA), The optimum temperature range of hyphal growth was $25-30^{\circ}C$ and the hyphal diameter was $4-10{\mu}m$. The typical clamp connections were observed in the hyphae of the fungus grown on PDA. The resulting sequence of 695 bp was deposited in GenBank. A BLAST search revealed that sequences of the this isolates showed >99% identity with those of Sclerotium rolfsii. On the basis of the morphological characteristics and phylogenetic analyses of molecular markers ITS rDNA, the fungi were identified as S. rolfsii. A pathogenicity test was carried out to fulfill Koch's postulates. To our knowledge, this is the first report of S. rolfsii on Ligularia fischeri in Korea.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.87-92
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• 2000

Recently, a new developed petroleiun spray oil(PSO; D-C Tron $Plus^{(R)}$) has been used to control key pests in integrated pest management (IPM) system of citrus orchards in Australia. The efficacy and phytotoxicity of the PSO against the citrus red mite (Panonychus citri) were compared with conventional pesticides (e.g.Tebufenpyrad, Bifenazate and Sun spray oil) in field condition in Jeju. And under PSO mixing spray with some fungicides, the occurrence of phytotoxic symptoms on citrus leaf was investigated. All concentrations of PSO spraying (0.25%, 0.33%, 0.5% and 1.0%) were significantly suppressed the citrus red mite to similar levels of other conventional pesticides. And the spraying of PSO levels ${\geq}0.5%$ was induced not only occurrence of some oil-sucked symptoms on leaf, but also increase of the dropping leaf and fruit rates. As results from mixing PSO spraying test with other fungicides, little burning on new flush shoot was founded only in PSO 1% plus Fluazinam treatment. From the results of this study, with the consideration of pesticidal efficacy and phytotoxicity, 0.25% and 0.33% PSO spraying level will be recommended for the control of citrus red mite during summer season in Jeju.