• The Plant Pathology Journal
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• v.19 no.4
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• pp.195-199
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• 2003

Pink root of onion occurred in the fields of the Onion Experimental Station and in the main onion cultivation area in Korea in 1998 and 1999, respectively. The casual fungus of pink root was isolated only from apricot agar. Formation of pycnidia and pycnidiospores of the fungus was highest in alternating cycles of 12 hours near ultraviolet light and 12 hours in dark condition. Its morphological characteristics and pigment formation on water agar were identical with that of Pyrenochaeta terrestris. The optimum temperature for the growth of the fungus and disease development was $25-28^{\circ}C$. When onion seeds were inoculated with the spore suspension, incubated in test-tube and sown in potted soil, disease symptoms developed in onion roots 7 and 30 days after inoculation.

• The Plant Pathology Journal
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• v.23 no.4
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• pp.295-299
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• 2007

These experiments were carried out to examine efficacy of soil solarization for control of pink root disease by means of mulching with transparent polyethylene sheets in the hot season. The effects of soil solarization on incidence of pink-root disease caused by Pyrenochaeta terrestris and on onion growth and on populations of soil fungi were investigated. Solarization was dramatically effective in reducing pink root incidence in onion seedling and harvested onion bulb. A 30-day and 40-day solarization treatment significantly improved seedling survival and increased yield of 'Changnyeong-deago' onion while decreasing incidence of pink root. Populations of soil fungi from fields planted to onion were assayed on selective media. Solarization treatment was effective in reducing populations of P. terrestris, Pythium spp., and Rhizoctonia sp. in soil. Increase of yield of onion bulbs was associated with control of soil-borne pathogenic fungi. Soil solarization had beneficial effects on yield, bulb diameter, or incidence of pink root.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1999.10a
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• pp.37.1-37
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• 1999

• Research in Plant Disease
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• v.13 no.2
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• pp.104-109
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• 2007

Pink root disease of onion, a known worldwide constraint upon onion production, significantly reduces crop levels in the main Korea cultivation area. In order to examine the effect of flooding on incidence of pink root disease caused by Pyrenochaeta terrestris and on onion growth and on populations of soil fungi, field experiments were conducted during two seasons, 2003/04 and 2004/05 at Onion Research Institute. Populations of soil fungi from fields were assayed on selective media. Flooding treatment was effective in reducing populations of P. terrestris, Pythium spp., and Rhizoctonia sp. in soil; fungal populations in soils flooded for 90 days were reduced to 1/2 to 1/3 of those in non-flooded soils. In nursery bed, protective activities of soils flooded for over 60 days were 93.5 to 99.2% and their pink root incidences were less than 5%, which were 1/11 to 1/18 of that in control. Increased yield of onion bulbs was associated with control of soil borne pathogenic fungi by flooding treatments. As flooding period was prolonged, bulb grade showed the tendency to increase. Soil flooding for over 60 days resulted in effective disease control, facilitated accurate planning of plant population in the field, extension of the growing-season and consequently higher yields of better quality.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.4
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• pp.297-302
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• 1990

This study was carried out to investigate the antimicrobial activity of the grapefruit seed extract (GFSE) The antimicrobial activity of GFSE was strong enough against such bacteria as Vibrio vulnificus, Vibrio fluvialis, Bacillus cereus, Staphylococcus aureus and Serratia sp. Growth of the above strains was inhibited by the GFSE'S concentration of 50 ppm. The growth of Vibrio vulnificus was completely inhibited by adding the 50 ppm GFSE to the nutrient broth medium with $3\%$ NaCl. The cell counts of Vibrio uulnfficus $5.2\times10^5$ at first in $5\%$ skim milk containing GFSE 0, 10, 30, 50 and 100 ppm were reduced to 35, 48, $5.6\times10^2,\;5.3\times10^3\;and\;9.6\times10^3/ml$ after 120 hours, respectively. And growth of Aspergillus Parasiticus, Asperillus versicolor, Penicillium funiculosum, Py-renochaeta terrestris and Trichoderma viride were inhibited by the concentration of GFSE 100, 50, 100, 10 and 30 ppm, respectively. The shelf life of Mulkimchi containing GFSE 50 and 100 ppm was 20 days longer than the control during storage at $5^{\circ}C\;and\;20^{\circ}C$.