• The Plant Pathology Journal
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• v.39 no.4
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• pp.351-360
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• 2023

Citrus melanose, caused by Diaporthe citri, has been one of the serious diseases, and chemical fungicides were used for protection in many citrus orchards of Jeju Island. Establishing a disinfectant resistance management system and reducing pesticide usage would be important for contributing to safe agricultural production. In this study, monitoring of chemical resistance was performed with 40 representative D. citri isolates from many citrus orchards in Jeju Island. Four different fungicides, kresoxim-methyl, benomyl, fluazinam, and prochloraz manganese, with seven different concentrations were tested in vitro by growing the mycelium of the fungal isolates on the artificial medium potato dextrose agar. Among the 40 fungal isolates, 12 isolates were investigated as resistant to kresoxim-methyl which could not inhibit the mycelium growth to more than 50%. Especially isolate NEL21-2 was also resistant against benomyl, whose hyphae grew well even on the highest chemical concentration. However, any chemical resistance of fungal isolates was found against neither fluazinam nor prochloraz manganese. On the other hand, in vivo bio-testing of some resistant isolates was performed against both kresoxim-methyl and benomyl on young citrus leaves. Typical melanose symptoms developed on the citrus leaves pre-treated with both agrochemicals after inoculation with the resistant isolates. However, no or less symptoms were observed when the susceptible isolates were inoculated. Based on these results, it was suggested that some resistant isolates of D. citri occurred against both systemic fungicides, which may be valuable to build a strategy for protecting citrus disease.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.944-950
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• 1989

Children with congenital cardiac defects associated with high pulmonary artery pressure may die despite accurate surgery. Postoperative mortality and morbidity have been attributed to acute rises in pulmonary artery pressure and resistance. Acute pulmonary hypertensive crisis is defined as a paroxysmal event in which pulmonary arterial systolic pressure rises to or above systemic levels followed by a rapid fall in systemic pressure and a minor pulmonary hypertensive event is defined as an acute rise in pulmonary arterial pressure to more than 80 % of systemic levels but without a fall in systemic pressure. From Oct. 1988 to Jul. 1989, we experienced 23 patients who showed many pulmonary hypertensive crises after operation in the Department of Thoracic and Cardiovascular Surgery, Seoul National University Children\ulcorner Hospital. Their preoperative PAP/SAPs were 53 to 123 %[mean 93.3%] and diagnoses were VSD[7], TAPVR[5], TGA[4], AVSD[3], MS[1], DORV[1], Truncus arteriosus[1], and AP window[l]. There were 9 deaths among 23 patients and they showed many pulmonary hypertensive crisis episodes during postoperative intensive care, which was managed by sedation, hyperventilation, oxygen, and acidosis correction and which decreased after using tolazoline. In view of our experience, we recommend that pulmonary artery pressure should be monitored in congenital heart defected patient with preoperative pulmonary hypertension to confirm and to manage the pulmonary hypertensive crisis accurately and using tolazoline is helpful in the treatment of pulmonary hypertensive crisis.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2004.10a
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• pp.36-38
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• 2004

Ethaboxam is a new fungicidal active ingredient that inhibits growth of plant pathogens specifically belonging to Oomycetes with protective, curative, systemic and translaminar activity in plants. Modes of action studies revealed that ethaboxam simultaneously inhibits cytoskeleton formation and mitochondrial respiration of Phytophthora infestans at low concentrations. There have been no indications of resistance development when tested for baseline resistance monitoring to 261 isolates of P. infestans in Korea and Europe and 150 populations of Plasmopara viticola populations in Europe for 3 years since 2000. In a selective study with vine trees artificially inoculated with P. viticola repeatedly for 10 generations in greenhouse, there have been no changes in sensitivity to ethaboxam among four natural populations of P. viticola. Furthermore, ethamoxam has not shown any cross resistance with azoxystrobin, mefenoxam, dimethomorph and cymoxanil. Based on the study results from modes of action and resistance development, ethaboxam appears to be unlikely to develop resistance in field applications.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.364.3-364
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• 2001

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.73.1-73
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• 2002

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2000.10a
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• pp.44.1-44
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• 2000

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.87.1-87
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• 2002

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.73.2-74
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• 2002

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.86.1-86
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• 2002

• Mycobiology
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• v.33 no.3
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• pp.131-136
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• 2005

Infection structures were observed at the penetration sites on the leaves of cucumber plants inoculated with Colletotrichum orbiculare using a fluorescence microscope. The cucumber plants were previously drenched with suspension of bacterial strains Pseudomonas putida or Micrococcus luteus. The plants pre-inoculated with both bacterial strains were resistant against anthracnose after inoculation with C. orbiculare. To investigate the resistance mechanism by both bacterial strains, the surface of infected leaves was observed at the different time after challenge inoculation. At 3 days after inoculation there were no differences in the germination and appressorium formation of conidia of C. orbiculare as well as in the callose formation of the plants between both bacteria pre-inoculated and non-treated. At 5 days, the germination and appressorium formation of the fungal conidia were, however, significantly decreased on the leaves of plants pre-inoculated with M. luteus at the concentration with $1.0{\times}10^7\;cfu/ml$. Furthermore, callose formation of plants cells at the penetration sites was apparently increased. In contrast, there were no defense reactions of the plants at the concentration with $1.0{\times}10^6\;cfu/ml$ of M. luteus. Similarly, inoculation P. putida caused no plant resistance at the low concentration, whereas increase of callose formation was observed at the higher concentration. The results of this study suggest that the resistant mechanisms might be differently expressed by the concentration of pre-treatment with bacterial suspension.