• Research in Plant Disease
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• v.29 no.3
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• pp.310-315
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• 2023

In May 2021, characteristic soft rot symptoms, including soft, watery, slimy, black rot, wilting, and leaf collapse, were observed on melon plants (Cucumis melo) in Gokseong, Jeollanam-do, Korea. A bacterial strain, designated KNUB-06-21, was isolated from infected plant samples, taxonomically classified, and phylogenetically analyzed using 16S rRNA and housekeeping gene sequencing. Strain KNUB-06-21 was also examined for compound utilization using the API ID 32 GN system and strain KNUB-06-21 was identified as Pectobacterium brasiliense. Subsequent melon stem inoculation studies using strain KNUB-06-21 showed soft rot symptoms similar to field plants. Re-isolated strains shared phenotypic and molecular characteristics with the original P. brasiliense KNUB-06-21 strain. To our knowledge, ours is the first report of P. brasiliense causing melon soft rot disease in Korea.

• Research in Plant Disease
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• v.29 no.4
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• pp.399-404
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• 2023

Agricultural activities and the number of farms in the subarctic regions have been increasing annually after the coronavirus disease 2019 pandemic to achieve food self-sufficiency. Potatoes are vulnerable to soft rot bacteria at all stages of production, storage, and transportation. A novel bacterium, Pseudomonas sp. N3-W, isolated from Alaska tundra soil, grows at 5-25℃ and produces extracellular protease(s). N3-W caused necrotic spots (hypersensitivity) in hot pepper leaves and soft rot disease (pathogenicity) in potato tubers. The psychrotolerant N3-W caused significant soft rot symptoms on potatoes at a broad temperature range (5℃, 15℃, and 25℃). In contrast, mesophilic Pectobacterium carotovorum KACC 16999 induced severe rotting symptoms in potatoes at their optimal growth temperature of 15℃ and 25℃. However, it barely produced symptoms at 5℃, which is the appropriate storage and transportation temperature for potatoes. The results of pathogenicity testing imply that psychrotolerant soft rot pathogens from polar regions may cause severe soft rot not only during the crop growing season but also during storage and transportation. Our study indicates the possibility of new plant pathogen emergence and transmission due to the expansion of crop cultivation areas caused by permafrost thawing in response to recent polar warming.

• Plant Disease and Agriculture
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• v.5 no.1
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• pp.61-63
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• 1999

Bacterial soft rot was observed on radish grown in Hongcheon, Kanwon-Do, Korea. The soft rot symptoms began as small water-soaked lesions. The water-soaked lesions enlarged rapidly in roots and produced a foul odor. When roots were affected in the field, the shoots also became infected and watery, causing infected plants to wilt, disorganize, and die. The causal organism was isolated from the lesions, and the identified as Erwinia chrysanthemi based on the morphological, physiological and biochemical characteristics. E. chrysanthemi is first described bacterium which causes bacterial soft rot on radish in Korea.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.55-62
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• 2022

The bacterial soft-rot disease is one of the most critical diseases in vegetables such as Chinese cabbage. The researchers isolated two bacteria (Pseudomonas kribbensis and Pantoea vagans) from diseased tissue samples of Chinese cabbages and confirmed them as being the strains that cause soft-rot disease. Lactic-acid bacteria (LAB), were screened and used to control soft-rot disease bacteria. The researchers tested the treatments with hypochlorous acid water (HAW) and LAB supernatant to control soft-rot disease bacteria. The tests confirmed that treatments with the HAW (over 120 ppm) or LAB (Lactobacillus plantarum PL203) culture supernatants (0.5 mL) completely controlled both P. kribbensis and P. vagans.

• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.361-363
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• 1998

Occurrence of soft rots was observed on celery that was massively grown in Pyungchang, Kangwon-Do, Korea. Soft rot symptom appeared first on the lower parts of the celery which eventually extended into whole aboveground parts of it. The casual organism isolated from the infected lesions was identified as Erwinia carotovora subsp. carotovora based on the physiological and chemical characteristics, and on the results of the Biolog program (Biolog Inc., U. S. A.). E. carotovora subsp. carotovora is the first described bacterium which causes the bacterial soft rot disease on celery in Korea.

• Research in Plant Disease
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• v.6 no.1
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• pp.15-18
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• 2000

A new bacterial disease was found on leaves of Kalanchoe blossfeldiana plant grown under vinyl-house condition in winter of 1998 in Taejeon. the first symptoms of the disease are the appearance of the water-soaked and light brown spots. Later they become soft rot with brown color. Causal bacteria were isolated from diseased tissues and the same symptoms as the natural infection were developed on Kalanchoe blossfeldiana leaves by needle-prick inoculation. The causal bacterium was identified Erwinia hervicola by its bacteriological characteristics. This is the first reported of this bacterium to occur on kalanchoe blossfeldiana plant in Korea. Therefore, we proposed to name the diseases as \"bacterial soft rot of Kalanchoe blossfeldiana\" by E. herbiocla.

• Research in Plant Disease
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• v.10 no.1
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• pp.82-85
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• 2004

Bacterial soft rot by Erwinia carotovora subsp. carotovora is one of the diseases causing the biggest damages in Chinese cabbage cultivation. This study was conducted to evaluate on suppressive effect of calcium fertilizer to bacterial soft rot of Chinese cabbage. Seven calcium fertilizers were selected for evaluation. And screening was conducted to select effective agents for controlling bacterial soft rot. When applied by the nursery test condition using mineral oil inoculation method with Chinese cabbage, calcium hydroxide had more suppressive efficacy than any other calcium fertilizer, While nitrogen fertilizer was induced the disease, calcium hydroxide was suppressed soft rot disease in field test as well as seedling test. Treatment of calcium+nitrogen fertilizer as well as calcium only showed a significant control effect in the field experiment with Chinese cabbage 'Sanchon' in 2003.

• Korean Journal Plant Pathology
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• v.12 no.1
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• pp.116-120
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• 1996

Water-soaked spots or lesions were observed on fruits or stems of melon plants at house-melon farms in Andong, Korea. The symptoms developed to soft rot of the fruits of wilting of the whole plants. The causal organism isolated from the water-soaked le-sions was identified as Erwinia carotovora subsp. carotovora based on the morphological and physiological characteristics. The causal bacterium was susceptible to not only two kinds of medical antibiotics but also two kinds of agrochemicals tested. Since the bacterial soft rot is a first described bacterial disease in melon in Korea, we propose to name the disease as "bacterial soft rot of melon".

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.236-238
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• 1987

A bacterial disease of elephant foot, Hydrosome rivieri Engl., was newly found in Taejon, Korea in August 1986. The affected plants showed symptoms of soft rot on leaf blades and petioles. Bacterial isolates from affected plants found to be pathogenic to elephant foots by antificial inoculation, producing similar symptoms with those produced naturally. The baterium was also pathogenic to carrot, Chinese cabbage, radish, potato and onion, and developed symptom of soft root on them. On the basis of bacteriological characteristics and pathogenicity, tested bacterium was identified as Erwinia carotovora subsp. carotovora and this disease was proposed to name 'Bacterial soft rot of elephant foot'.

• Research in Plant Disease
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• v.21 no.4
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• pp.255-260
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• 2015

We investigated influence of three commercial antibiotics viz., oxolinic acid, streptomycin, and validamycin A, on biocontrol and plant growth promoting activities of Bacillus vallismortis EXTN-1 and BS07M in Chinese cabbage. Plants were pre-drenched with these strains followed by antibiotics application at recommended and ten-fold diluted concentration to test the effect on biocontrol ability against soft rot caused by Pectobacterium carotovorum SCC1. The viability of the two biocontrol strains and bacterial pathogen SCC1 was significantly reduced by oxolinic acid and streptomycin in vitro assay, but not by validamycin A. In plant trials, strains EXTN-1 and BS07M controlled soft rot in Chinese cabbage, and there was a significant difference in disease severity when the antibiotics were applied to the plants drenched with the two biocontrol agents. Additional foliar applications of oxolinic acid and streptomycin reduced the disease irrespective of pre-drench treatment of the PGPRs. However, when the plants were pre-drenched with EXTN-1 followed by spray of validamycin A at recommended concentration, soft rot significantly reduced compared to untreated control. Similarly, strains EXTN-1 and BS07M significantly enhanced plant growth, but it did not show synergistic effect with additional spray of antibiotics. Populations of the EXTN-1 or BS07M in the rhizosphere of plants sprayed with antibiotics were significantly affected as compared to control. Taken together, our results suggest that the three antibiotics used for soft rot control in Chinese cabbage could affect bacterial mediated biocontrol and plant growth promoting activities. Therefore, combined treatment of the PGPRs and the commercial antibiotics should be carefully applied to sustain environmental friendly disease management.