• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.459-480
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• 1991

Physilogical disorders of P. ginseng occurred in farmer's field were reviewed in relation to symptom. In root, red skin, rough skin, rust, root rot complex, round root, fine root stripe, freezing injury, cracking, sleeping and uneven emergence were frequently appeared. In leaf and stem, yellowing, early defoliation, leaf bum, Papery leaf, white freezing injury, wind injury, stem cracking were the main troubles. Red skin of root and leaf yellowing gave the greatest negative impact on ginseng production. Some cases of damage by pesticides, excess boron and industrial pollutants were reported. Physiological disorders related to quality factors, such as inside cavity, inside white sponge-like ect. after processing were discussed.

• Korean Journal of Plant Resources
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• v.19 no.3
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• pp.436-439
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• 2006

This study was carried out to obtain basic information for optimum storage method of leaf, stem and root of Angelica acutiloba Radix, which is being utilized as major cultivated herbal medicine materials, root of Angelica acutiloba was stored for 3 months in different packing materials and sealing methods, such as punched packing, sealing and vacuum packing. The results are summarized as follows. The loss in weight as influenced by packing materials and sealing degree was the lowest at vacuum packing and complete sealing condition with transparent polyethylene film. The ratio of root rot during the storage period was not significantly different between polyethylene films, but it was significantly different between sealing conditions. Therefore, vacuum packing and complete sealing with polyethylene film are desirable storage condition for Angelica acutiloba Radix.

• The Plant Pathology Journal
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• v.20 no.3
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• pp.165-171
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• 2004

A total of 62 isolates of Bipolaris cactivora causing cactus stem rots were isolated from major cactus-growing areas in Korea. Colony morphology of the isolates on potato-dextrose agar was differentiated into aerial (CA) and non-aerial mycelial types (CB). CA had profound aerial mycelium with grayish brown (CA-l), light brownish (CA-2), and brownish (CA-3) pigmentations; respectively, while CB had dark brownish pigmentations. CA had conidia of less dark pigmentation and acute terminal end. CB had darker and more round-end conidia. Twenty-eight amplified fragments were produced by polymerase chain reaction (PCR) with a set of 2 random primers. The sizes of amplified DNA fragments ranged approximately from 0.1 to 2.3 kb. The isolates were classified into 2 major genomic DNA random amplified polymorphic DNA (RAPD) groups at the genomic similarity of 97.7％ and 95.1％, respectively. Cluster analysis of genetic similarity among the isolates generated a dendrogram that clearly separated all isolates into SA or SB. This result suggests that there may be two morphotypes of B. cactivora in Korea that may differ in their genetic constitutes.

• The Korean Journal of Community Living Science
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• v.17 no.3
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• pp.89-97
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• 2006

This study was conducted to compare soybean growth and yield and the degree of weed emergence according to no-tillage and conventional tillage system in two different drained paddy fields, loam of Chilgok series and silty clay loam of Deokpyeong series. In both soil conditions, the maturing time of the soybeans by the no-tillage system was two days earlier than that by the conventional tillage system. In the loam of Chilgok series, the stem length of the soybeans in the no-tillage system was 5.7 cm longer than that in the conventional tillage system. The miss-planted rate and diseased plants of black root rot (Calonectria iliacola) in the no-tillage system were 9.2% and 2.8% lower, respectively than those in the conventional tillage system. Also, the nodulation and seed yield in the no-tillage system were 32% and 13% more, respectively, than those in the conventional tillage system. In the silty clay loam of Deokpyeong series, the stem length of the soybeans in the no-tillage system was 4.6cm shorter than in the conventional tillage system. The diseased plants of black root rot (Calonectria iliacola) in the no-tillage system were 4.2% lower than those in the conventional tillage system. Also, no significant difference in the seed yield between the no-tillage and conventional tillage systems was observed. On the other hand, there was a lower occurrence of weed in the no-tillage system than in the conventional tillage system, and the income increased by 19% owing to yield increase and reduced management costs.

• The Plant Pathology Journal
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• v.35 no.6
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• pp.698-704
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• 2019

Phytophthora root and stem rot (PRSR) caused by Phytophthora sojae is one of the most destructive diseases of soybean. PRSR recently became an issue as soybean cultivation in paddy fields increased in South Korea. The management of PRSR mainly involves R-gene-mediated resistance, however, little is known about the resistance in Korean cultivars. Major Korean soybean cultivars were investigated for the presence or absence of R-gene-mediated resistance to four P. sojae isolates, two of which were new isolates. Isolate-specific reactions were observed following P. sojae inoculation. Of 21 cultivars, 15-20 cultivars (71.4-95.2%) showed susceptible reaction for each isolate. Ten cultivars were susceptible to all the isolates, and six cultivars were identified to have R-gene-mediated resistance to one or two isolates. The results of this study would provide a framework for the discovery of resistant cultivars, development of new cultivars resistant to P. sojae, and investigation of pathogenic diversity of P. sojae population in South Korea.

• The Plant Pathology Journal
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• v.28 no.2
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• pp.185-190
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• 2012

Sclerotinia sclerotiorum is a serious pathogen which causes yield loss in many dicotyledonous crops including potato. The objective of this study was to assess the potential of biofumigation using three Brassica crops including Brassica napus, B. juncea and B. campestris against potato stem rot caused by S. sclerotiorum by in vitro tests. Both macerated and irradiated dried tissues were able to reduce radial growth and sclerotia formation of five pathogen isolates on PDA, but macerated live tissues were more effective. Compared with other tested crops, B. juncea showed more inhibitory effect against the pathogen. The volatile compounds produced from macerated tissues were identified using a gas chromatograph-mass spectrometer. The main identified compounds were methyl, allyl and butyl isothiocyanates. Different concentrations of these compounds inhibited mycelial growth of the pathogen in vitro when applied as the vapor of pure chemicals. A negative relationship was observed between chemicals concentrations and growth inhibition percentage. In this study, it became clear that the tissues of local Brassica crops release glucosinolates and have a good potential to be used against the pathogen in field examinations.

• The Korean Journal of Mycology
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• v.52 no.2
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• pp.73-96
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• 2024

Root and stem rot caused by Phytophthora palmivora is one of the most serious diseases affecting durian production in Thailand where metalaxyl, an effective fungicide against oomycetes, has been used extensively for a long period to control this disease. Although field isolates of P. palmivora resistant to metalaxyl exist in Thailand, a molecular basis for P. palmivora has not yet been elucidated regarding metalaxyl resistance. The current study tested whether P. palmivora RPA1 (the DNA-directed RNA polymerase I subunit gene), a homolog gene of RPA190 associated with metalaxyl resistance in some isolates of Phytophthora infestans, had a role in the resistance mechanism toward metalaxyl. In total, 40 durian-derived isolates of P. palmivora were assessed for metalaxyl sensitivity using a mycelial growth inhibition assay. The effective concentrations for 50% mycelial growth inhibition values for all isolates tested were in the range 0.01-872.88 mg/L. The isolates were clustered into three groups: sensitive (n=23), moderately resistant (n=11), and resistant (n=6) groups. No polymorphism was revealed based on multiple alignment analysis of the amino acid sequences translated from the corresponding DNA sequences in the region of RPA1 of the metalaxyl-sensitive (n=5), moderately resistant (n=2), and resistant isolates (n=6). Furthermore, investigation of the RPA1 expression among these representative isolates (n=3, each group) indicated that RPA1 expression may not be involved in the regulation of P. palmivora resistance to metalaxyl. Based on this line of evidence, there was no detected relationship regarding metalaxyl resistance and P. palmivora RPA1.

• Journal of Bio-Environment Control
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• v.19 no.4
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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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• v.20 no.4
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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.

• Research in Plant Disease
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• v.10 no.4
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• pp.324-330
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• 2004

This studies were investigated the occurrence of sclerotinia rot at the crisphead lettuce field in Uiryeong-Gun, Gyeongsangnam-Do from January to May in 2003. Average incidence rates of sclerotinia rot on crisphead lettuce was up to 21.9% at the five plastic houses. A total of 140 isolates of Sclerotinia sp. were obtained from diseased leaves of crisphead lettuce. Among them, the fungi YR-1 was isolated, which showed highly virulent on the whole plant. the YR-1 was identified as Sclerotinia sclerotiorum based on the formation, color, shape and size of sclerotium and apothecium. For the pathogenicity test, the most suitable inoculum quantity of YR-1 strain was selected as the triturated mycelial suspension of $A_{550}$=0.8, 40 ml showing disease incidence of 94%, and the symptom showed as same as at the fields, the leaves and stem had rotten and developed white downy mycelial at the diseased lesion on the leaves and stems, and produced black and irregular sclerotinia. This is the first report on the pathogenicity test using by triturated mycelial suspension-inoculum of the pathogen for the sclerotinia rot of crisphead lettuce.