• The Plant Pathology Journal
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• v.22 no.1
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• pp.75-89
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• 2006

The actinomycete strain JK-1 that showed strong inhibitory activity against some plant pathogenic fungi and oomycetes was isolated from Jung-bal Mountain in Ko-yang, Korea. The strain JK-1 produced spores singly borne on sporophores and the spores were spherical and 0.9-1.2 11m in diameter. The cell wall of the strain JK-1 contained meso-diaminopimelic acid. The actinomycete strain JK-1 was identified as the genus Micromonospora based on the morphological, physiological, biochemical and chemotaxonomic characteristics. From the 168 rDNA analysis, the strain JK-1 was assigned to M aurantiaca. The antibiotic MA-1 was purified from the culture broth of M aurantiaca JK-1 using various purification procedures, such as Diaion HP20 chromatography, C18 flash column chromatography, silica gel flash column chromatography and Sephadex LH-20 column chromatography. $^{1}H-$, $^{13}C-NMR$ and EI mass spectral analysis of the antibiotic MA-1 revealed that the antibiotic MA-1 is identical to phenylacetic acid. Phenylacetic acid showed in vitro inhibitory effects against fungal and oomycete pathogens Alternaria mali, Botrytis cinerea, Magnaporthe grisea, Phytophthora capsici and yeast Saccharomyces cerevisiae at < 100 $\mug$ $ml^{-1}$. In addition, phenylacetic, acid completely inhibited the growth of Sclerotinia sclerotiorum, Bacillus subtilis, Candida albicans, Xanthomonas campestris pv. vesicatoria at < $\mug$ $ml^{-1}$. Phenylacetic acid strongly inhibited conidial germination and hyphal growth of M grisea and C. orbiculare. Phenylacetic acid showed significantly high levels of inhibitory' effect against rice blast and cucumber anthracnose diseases at 250 $\mug$ $ml^{-1}$. The control efficacies of phenylacetic acid against the two diseases were similar to those of commercial compounds tricyclazole, iprobenfos and chlorothalonil .n the greenhouse.

• Current Research on Agriculture and Life Sciences
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• v.10
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• pp.117-123
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• 1992

Twenty and 24 lines selected from Korean local cultivar, Kalmi and Punggak, respectively, were grown in the University experiment farm to select promising lines for recurrent parent in a backcross breeding program for incorporation of resistance to Phytophthora capsici and Xanthomonas campestris pv vesicatoria into the Korean local cultivars. All the selections of 'Kalmi' and 'Punggak' were relatively late in maturity and the range of the variation was wider in the selections of 'Kalmi' than in those of 'Punggak'. Many of the selections from 'Kalmi' were vigorous, high in sugar content, and tolerant to virus in the field. Many of the selections from 'Punggak' were bearing large fruits with thick pericarp and high milling percentage. Line 6, 9, 14, 18 of 'Kalmi' and line 14, 16, 18 of 'Punggak' were selected as promising lines for recurrent parent in the backcross program.

• Research in Plant Disease
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• v.7 no.1
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• pp.37-41
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• 2001

This experiment was carried out to investigate the prevention of bacterial shot hole by Bordeaux mixture when it was sprayed on peach trees after harvest. bordeaux mixture was sprayed on \`Mibaeko\` peach trees 1 to 3 times after mid September, and the occurrence of bacterial shot hole was examined in the next year. Bacterial shot hole in leaves appeared from mid May and thereafter increased gradually. The more times was sprayed Bordeaux mixture, the less peaches were diseased with bacterial shot hole. At the beginning of August, the peach harvest time, the disease incidence of the untreated control plot was 27.4 to 38.1%, while the disease incidence was 9.7 to 31.8% when Bordeaux mixture was sprayed. The control value ranged from 16.5 to 64.6%. Occurrence of the fruit disease was similar to that of the leaf disease. Incidence of the fruit disease in the untreated control was 17.2 to 21.6%, but incase of the chemical treatment, it was 5.0 to 12.2 %, showing 41.9 to 70.9% of the control value. Chemical injury on peach leaves were not found in the 4-12 and 408 types, but occurred in some degrees in the 6-6 type of Bordeaux mixture.

• Research in Plant Disease
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• v.21 no.2
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• pp.89-93
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• 2015

This study was carried out to develop the economic thresholds for the control of bacterial spot of red pepper. The correlation between diseased leaf rate and yield in field was Y=-0.724X+281.58, $R^2=0.78$, $r=-0.88^{**}$. The correlation between diseased leaf rate and yield loss in field was Y=0.813X+15.95, $R^2=0.78$, $r=0.88^*$.We found that control thresholds was below 30.3% diseased leaves rate per plant in field. The economic control thresholds for bacterial spot of red pepper was below 16.3%.

• Research in Plant Disease
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• v.25 no.3
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• pp.136-142
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• 2019

Drought stress is considered as one of major abiotic stresses; it leads to reduce plant growth and crop productivity. In this study, we selected bacterial strains for alleviating drought stress in chili pepper plants. As drought-tolerant bacteria, 28 among 447 strains were pre-selected by in vitro assays including growth in drought condition with polyethylene glycol and plant growth-promoting traits including production of 1-aminocyclopropane-1-carboxylate deaminase, indole-3-acetic acid and exopolysaccharide. Sequentially, 7 among pre-selected 28 strains were screened based on relative water content (RWC); GLC02 and KJ40, among seven strains were finally selected by RWC and malondialdehyde (MDA) in planta trials under an artificial drought condition by polyethylene glycol solution. Two strains GLC02 and KJ40 reduced drought stress in a natural drought condition as well as an artificial condition. Strains GLC02 or KJ40 increased shoot fresh weight, chlorophyll and stomatal conductance while they decreased MDA in chili pepper plants under a natural drought condition. However, two strains did not show biocontrol activity against diseases caused by Phytophthora capsici and Xanthomonas campestris pv. vesicatoria in chili pepper plants. Taken together, strains GLC02 or KJ40 can be used as bio-fertilizer for alleviation of drought stress in chili pepper plants.