• Journal of Bio-Environment Control
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• 제19권4호
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• pp.305-310
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• 2010

This study was carried out to investigate the effect of air humidity and water content of medium on the growth and physiological disorder of paprika in summer hydroponics. Treatments were composed of air humidity of control (over 90%) and dehumidification (low 90%) and water content of 80% and 50%. Time domain reflectometry (TDR) sensors and dehumidifier were used in a drip irrigation system and control system of air humidity, respectively. The early growth of paprika was not affected by air humidity but increased by high water content (80%) of medium. Mean fruit weight was reduced at high air humidity and low water content (50%) of medium, but the fruit number per plant and yield were increased at low air humidity. The incidence of brown fruit stem increased with increasing air humidity and water content of medium. Rate of blossom end rot increased in the low water content medium compared with the high water content medium. The nitrogen (N) was higher content in brown fruit stem than normal stem, but calcium (Ca) was lower.

• Journal of Bio-Environment Control
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• 제20권4호
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• pp.258-262
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• 2011

This study was carried out to investigate the effect the water content in substrates as according to growth stage on the growth and yield of paprika in summer hydroponics. Treatments of I, II and III were composed of 55-65-60, 50-60-55 and 45-55-50 % in water contents of growth stages, respectively. Time domain reflectometry (TDR) sensors were used in a drip irrigation system. The early growth of paprika was increased by high medium water content of treatment I. Mean fruit weight was not affected by medium water content, but the fruit number per plant and yield were increased at high medium water content of treatment I. The yield of treatment I was higher than that of treatment II and III. The incidence of brown stem fruit, blossom end rot and sunburn was decreased with increasing water content of medium. Occurred in the low water content of medium. The nitrogen (N) was higher content in brown stem fruit than normal stem, but mineral contents such as potassium (K), calcium (Ca), magnesium (Mg) etc. were not affected.

• Journal of Mushroom
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• 제9권4호
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• pp.198-201
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• 2011

Cobweb disease symptoms were observed in a mushroom farm in Buye, Korea during a disease survey in 2008-2011. Five isolates of Cladobotryum sp. were obtained from the infected caps and stipes. These isolates of Cladobotryum sp. were identified as C. mycophilum based on their morphological, cultural characteristics and analysis of the ITS sequences. Early symptoms were noticed as round, fleshy, yellowish brown lesions on mushroom caps. Late symptoms progressed when the parasitic fungus formed white cobweb circular colonies on dead or damaged pinheads, spread on the surface of the casing, and covered entirely fruiting bodies. Optimal temperature and pH for mycelial growth on MEA is $23^{\circ}C$ and 6.0. Microscopically the spores of the fungus are large and most 2~3 celled produced on vertically branched conidiophores. Mushroom caps turned dark brown and shrunk due to soft rot. Testing of sensitivity to selected fungicides showed that isolate was highly resistance to Mancozeb and Thiophanate-methyl, moderately sensitivity to Iprodione, and highly sensitivity to Benomyl, Prochloraz-Mn and Carbendazim.

• The Plant Pathology Journal
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• 제19권4호
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• pp.203-204
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• 2003

Decayed samples of marketed mungbean sprout were collected from Sacheon, Suncheon, and Dangjin cities in Korea. Initial symptom on hypocotyls was dark-brown diamond speck, which developed into enlarged sunken brownish-black spot with irregular margin, followed by softening yellowish decay. Brown speck on cotyledon further developed into irregular lesions. This study isolated the fungus Colletotrichum sp. The fungal colony was pale orange, which turned greenish gray after 1 week at $25^{\circ}C$. Colony of reverse side in a petri dish was pink. Neither conidiomata nor setae were present in the culture. Typical fusiform conidia sized 7.5-15.0$\times$2.5-2.9 $\mu\textrm$were hyaline, aseptate, smooth, and had salmon color in mass. Conidiogenous cells were phialidic, hyaline, smooth, and cylindrical with terminal distinct collarette. Basedon these mycological characteristics, the casual organism was identified as Colletotrichum acutatum. This is first report of Colletotrichum acutatum in Korea.

• Weed & Turfgrass Science
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• 제2권3호
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• pp.306-311
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• 2013

Pythium blight occurred by Pythium aphanidermatum on chewing fescue cv. "Jamestowm II" from early June, 2010 and 2011 at the test field in Daegu University in Gyeongbuk Province, Korea. Disease symptoms on the turfgrass were leaf blights dying from the leaf tip and root rot, which appeared patches of brown to dark brown color or gray brown color in the field. The pathogens (40-1 isolate) of Pythium blight was isolated from the diseased leaf and crown tissue and cultured on potato-dextrose agar (PDA) for identification. Lobulate sporangia were inflated, complex structures, and filamentous sporangia were usually indistinguishable from vegetative hyphae. Sequences of ribosomal RNA gene of the fungus were homologous with similarity of 100% to those of P. aphanidermatum isolates in GenBank database. Pathogenicity was also confirmed on the chewing fescue, creeping betgrass and Kentucky bluegrass by Koch's postulates. This is the first report of Pythium blight on chewing fescue caused by P. aphanidermatum in Korea.

• Korean Journal of Environmental Agriculture
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• 제1권2호
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• pp.99-104
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• 1982

These studies were carried out to investigate the damage of root rot of hop by heptachlor residues in soil at nine farm fields and pot experiment for two years from 1980 to 1981. 1) Pot experiment results indicated that root rot of hop occurred in farm field were caused by heptachlor phytotoxicity. 2) The damage of root rot of the hop was found by heptachlor residues in soil. Hop root in the low concentration of heptachlor was turned to brown mottle, and then rotted. In high concentration, the hop root was decreased in number, blocked in growth, and resulted to greyish change with death. 3) Hop vine damaged by heptachlor was hardened and broken with ease. 4) Heptachlor epoxide which was inferred to be the main cause of hop root rot gave the damage to hop at 0.009 ppm reisdues in soil. 5) The phytotoxicity of heptachlor was proved to last for 10 years or more in this study.

• Research in Plant Disease
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• 제12권3호
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• pp.178-184
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• 2006

The 18 isolates of soybean red crown rot pathogen(Calonectria ilicicola) were isolated from infected soybean plants showing chlorosis symptom and red perithecia sign in 2002 and 2003 season in Korea. The morphological characteristics of the typical isolate SC03-15, such as macroconidia and macrovesicles in anamorph as well as perithecia, asci and ascospores in teleomorph, were observed from red crown rot pathogens. The perithecia were red-brown globose to ovoid, and $357.9(312.5{\sim}391.5.7){\mu}m$ high and $474.3(419{\sim}535){\mu}m$ diameter. Asci were hyaline and clavate and included 8 ascospores, which were straight to slightly curved, 1(-3)-septate, and $36.9(31.1{\sim}49.4){\times}5.2(4.5{\sim}6.1){\mu}m$. Macroconidia in anamorph were cylindrical, hyaline and in size $73.2(68.1{\sim}77.6){\times}5.8(4.9{\sim}6.8){\mu}m$. Further identification process was performed through molecular method, such as a phylogenetic analysis by rDNA sequencing of ITS and $\beta$-tubuline genes of all isolates tested in this study. All isolates were identified as Calonectria ilicicola by DNA sequencing of ITS and $\beta$-tubuline genes, and morphological characteristics.

• Research in Plant Disease
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• 제15권3호
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• pp.259-261
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• 2009

Sclerotinia shoot rot of Grapevine(Vitis labruscana) occurred at Gapyeong and Yeongwol area from 2003 to 2005. Infected plants showed shoot blight at the one-year-old fruit bearing branches. The first visible symptom noticed was wilting and blighting of the branches. The obvious and typical initial symptom is the presence of a cottony, white, dense mat of mycelial growth on the surface of the diseased lesions. The base or stem of the infected young shoots develop a pale brown rotted area, which girdled and killed shoots. In advanced stages of the disease, stems and branches became bleached and eventually died. The isolates collected from diseased grapevine stem were identified as Sclerotinia sclerotiorum based on the morphological and cultural characteristics. The pathogenicity test revealed that Vitis vinifera(cultivar: Kyoho) was stronger than V. labruscana(cultivar: Campbell early) to the pathogen. This is the first report on sclerotinia shoot rot of grapevine in Korea.

• Research in Plant Disease
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• 제23권2호
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• pp.202-205
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• 2017

Pink rot appeared in greenhouse-grown sunflower (Helianthus annuus L.) in Jeonju, Korea. The symptoms appeared as brown discoloration of sunflower head and progressed into stem in advanced stage. In order to investigate the causal organism of this disease, we isolated a fungus from the infected seeds and maintained the isolated fungal culture on potato dextrose agar medium. Conidiophores were simple or branched, 62.5 to $123.1{\mu}m$ long. Conidia were produced in basipetal chains, ellipsoidal to pyriform with oblique and prominent truncate basal scars, two-celled, hyaline and measured $10.2-21.4{\times}7.5-12.6{\mu}m$. The fungus was inoculated to a new sunflower plant and showed the typical blight on the leaves. Study of morphological characters, pathogenicity tests and sequence analysis revealed that the isolated fungus is confirmed to be Trichothecium roseum. To our knowledge, this is the first report of pink rot on sunflower caused by T. roseum in Korea.

• Research in Plant Disease
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• 제12권2호
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• pp.134-138
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• 2006

A new bacterial disease of broccoli (Brassica oleracea var. italica) was observed on field-grown plants in Pyungchang during 2003 and 2004. Seedling infections first appeared as a blackening along the margins of the cotyledon. Cotyledon shriveled and dropped off. Infected seedlings were stunted and yellowed and eventually died. The disease was easily recognized by the presence of yellow, V-shaped, or U-shaped areas extending inward from margin of the leaf. As the disease progressed, the yellow lesions turned brown and the tissues died. Isolations made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow-pigmented bacterium typical of a xanthomonad. Two bacterial strains were purified and used for further tests. Pathogenicity of strains was confirmed on 3-week-old crucifer (cabbage, Chinese cabbage, kale, radish and broccoli) plants cut by scissors with bacterial suspensions containing $10^8 cfu/ml$ of phosphate buffered saline. The Biolog and fatty acid analyses and 16S rDNA sequencing of two strains (SL4797 and SL4800) from broccoli black rot showed that they could be identified as X. campestris pv. campestris because of their high similarity to the tester strain (X. campestris pv. campestris NCPPB528) with a match probability of 100%. This is the first report of black rot of broccoli in Korea.