• Research in Plant Disease
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• v.11 no.2
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• pp.89-92
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• 2005

In 2004, average temperature was higher, and rainfall was less than those of previous year, The diseases of rice, barley, pepper, chinese melon, apple and oriental pear were surveyed. Seedling diseases, leaf blast, sheath blight and bacterial blight of rice, phytophthova blight, virus diseases and anthracnose of pepper, and sudden wilt syndrome and powdery mildew of chinese melon grown in plastic greenhouse were severe. Especially, sheath blight and bacterial blight of rice occurred two times higher than those of previous year, Panicle blight of rice decreased about 4 times, compared with the previous year, presumed that the lower rainy days, rainfall and RH suppressed spread of the fungal pathogens to panicles of rice. Lower rainfall during mid- and late Aug caused three-times less occurrence of phytophtora blight of red-pepper than that of the previous year, Another diseases surveyed occurred similar or less than those of the previous year.

• Research in Plant Disease
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• v.14 no.1
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• pp.37-42
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• 2008

Bacillus subtilis BD0310 isolated from tea leaves was used for the development of a biofungicide against Pestitalotiopsis longiseta causing gray blight of tea plants. After mass culture of the antagonistic bacteria, the biofungicide formulated as a suspension concentrate was evaluated for its control efficacy against the gray blight of tea plant in a greenhouse and a tea plantation, respectively. Spray of the biofungicide 2 days before inoculation of P. longiseta inhibited more efficiently the development of gray blight compared with spray of the biofungicide 2 days after inoculation of the pathogen onto the leaves of tea plants in a greenhouse. In the field investigation under application of the biofungicide in 2005 and 2006, control efficiencies increased according to the number of spray of the biofungicide. Control efficiencies of the biofungicide were 52.4%, 66.7%, 71.4% and 85.7% against gray blight in 4 times spray of the biofungicide alone at 7 days interval, 6 times spray of the biofungicide alone at 7 days interval, 2 times alternate spray of biofungicide and chemical fungicide at 7 days interval and 4 times spray of chemical fungicide alone at 7 days interval, respectively. Therefore, the alternate application of the biofungicide and chemical fungicide at 7 days interval can increase the control efficiency with reduction of the amount of chemical fungicides and the number of spray for the control of gray blight of tea plants in the field.

• Research in Plant Disease
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• v.24 no.3
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• pp.182-192
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• 2018

Since fire blight (Erwinia amylovora) firstly broke out at mid-Korea in 2015, it is necessary to investigate potential spread of the invasive pathogen. To speculate environmental factors of fireblight epidemic based on disease triangle, a fire blight predicting program, MARYBLYT, was run with the measured meteorological data in 2014-2017 and the projecting future data under RCP8.5 scenario for 2020-2100. After calculating blossom period of Singo pear from phenology, MARYBLYT was run for blossom blight during the blossom period. MARYBLYT warned "Infection" blossom blight in 2014-15 at Anseong and Cheonan as well as Pyungtak and Asan. In addition, it warned "Infection" in 2016-17 at Naju. More than 80% of Korean areas were covered "Infection" or "High", therefore Korea was suitable for fire blight recently. Blossom blight for 2020-2100 was predicted to be highly fluctuate depending on the year. For 80 years of the future, 20 years were serious with "Infection" covered more than 50% of areas in Korea, whereas 8 years were not serious covered less than 10%. By comparisons between 50% and 10% of the year, temperature and amount of precipitation were significantly different. The results of this study are informative for policy makers to manage the alien pathogen.

• Research in Plant Disease
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• v.26 no.4
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• pp.239-249
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• 2020

To find out the cause of the fire blight outbreak in apples and pears of Korea in 2019, we investigated disease appearing situation of thirty fire blight infected orchards, and interviewed farmers to determine the cultivation characteristics. Fire blight occurred mostly in orchards that had infected more than 2 years before. The cause of this were as follows: farmers did not know the symptoms of the disease properly. It is presumed that it has spread from the first occurrence to the surrounding orchards by flower-visiting insects or farmers and to a short distance or a long distance by the same cultivator or co-farmer. These series of processes repeated in the newly spreading area, and then disease reports increased as farmers became aware of fire blight. To minimize the spread of fire blight in Korea, it suggested that thorough education of farmers for early diagnosis and quantitative detection technology that can diagnose even in no symptom showing plants. And chemical or biological spraying systems suitable for domestic cultivation methods, which are producing large fruits, and molecular epidemiological studies of pathogens.

• Research in Plant Disease
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• v.26 no.4
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• pp.222-228
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• 2020

Erwinia amylovora, a causal bacterium of fire blight disease, is registered as a prohibited quarantine pathogen in Korea. To control the disease, the government should diagnose the disease, dig and bury the host trees when fire blight occurs. Fire blight was the first reported in 43 orchards of Anseong, Cheonan, and Jecheon in 2015, and 42.9 ha of host trees were eradicated. However, the disease spread to eleven cities, so that 348 orchards and 260.4 ha of host trees were eradicated until 2019. Fire blight of Asian pear occurred mainly in the southern part of Gyeonggi, and Chungnam province, on average of 29±9.2 orchards per year. And the age of the infected trees were mostly 20-30 years old. In apple trees, the disease occurred mainly in the northern part of Gyeonggi, Gangwon, and Chungbuk province, on average of 41±57.6 orchards per year, increased highly in 2018 and 2019. The age of infected apple trees were under 20 years old. Therefore, because the disease spread rapidly in young apple trees, spraying control agents to the trees in a timely manner and removing infected trees quickly are important to prevent the spread of fire blight in the orchard of immature trees.

• Research in Plant Disease
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• v.9 no.3
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• pp.179-182
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• 2003

Effect of potassium phosphonate on control of potato late blight was evaluated at two fields in Jeju island. The chemical showed 82.5% control value in field located at low seacoast with 100 m elevation, while dimethomorph copper oxychloride showed 75.9 % control value. However, its control value was only 40% in another field located at mid-hilly area with 300 m elevation, in which environmental conditions of high hummudity and often rainfall were favorable to the disease development. Application intervals of the phosphonate from 7 to 15 effectively suppressed the disease and did not show statistically different control values among the spraying intervals. Results indicated that phosphonate similarly or more effectively controls potato late blight than fungicide, however, its control value could be vared according to enviromental conditions for the disease development and 15-d spraying intervals ware sufficient to suppress ther disease.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.197-209
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• 1995

This paper is a third report about the new fungal diseases of economic resource plants in Korea. It contains short descriptions on symptoms, occurrence conditions, pathogen, and some phytopathological notes for each of 10 fungal plant diseases. They are angular leaf spot of Achyranthes japonica by Cercospora achyranthis causing leaf spot and defoliation in the shade of plants, leaf spot of Armoracia lapathifolia by Cercospora armoraciae causing leaf spot to blight from the rainy season to autumn, hypophyllous mold of Dioscorea tokoro by Distocercospora pachyderma causing leaf spot and yellowing, hypophyllous mold of Artemisia spp.by Mycovellosiella ferruginea causing leaf spot and yellowing, angular leaf spot of Aralia elata by Pseudocercospora araliae causing velvety leaf spot and defoliation, hypophyllous mold of Lycium chinense by Pseudocercospora chengtuensis causing velvety leaf spot and defoliation from the rainy season to autumn, angular leaf spot of Diospyros lotus by Pseudocercospora disospyri-morrisianae causing leaf spot and defoliation from summer to autumn, brown leaf spot of Impatiens textori by Pseudocercospora nojimae causing leaf spot to blight from the rainy season, leaf spot of Cephalonoplos segetum by Ramularia cirsii causing leaf spot to blight throughout the growing season, and white mold of Leonurus sibiricus by Ramularia leonuri causing leaf spot to blight mostly in autumn.

• Research in Plant Disease
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• v.21 no.4
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• pp.261-267
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• 2015

During the period from 2013 to 2014, disease occurrences by various pathogens in apple cultivars have been investigated in northern Gyeongbuk province of Korea. Anthracnose, white rot, Alternaria leaf spot, Marssonina blotch, and bacterial shoot blight as major diseases have been observed. Pathogens isolated from the symptomatic plants were identified as Colletotrichum gloeosporioides for anthracnose, Botryosphaeria dothidea for white rot, Alternaria alternata for Alternaria leaf spot, Marssonina mali for Marssonina blotch, and Pseudomonas syringae pv. syringae for bacterial shoot blight. Of all diseases, the bacterial shoot blight has been severely increased in chronically infested fields in Gyeongbuk province.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1236-1242
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• 2011

Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating pathogen to Oryza sativa and has been shown to cause bacterial blight. Two bioactive compounds showing antimicrobial activities against Xoo strain KACC 10331 were isolated from a Streptomyces bottropensis strain. The ethyl acetate extract was fractionated on a Sephadex LH-20 column, and then purified by preparative HPLC. The purified compounds were identified as bottromycin A2 and dunaimycin D3S by HR/MS and $^1H$ NMR analyses. The MIC value against Xoo and the lowest concentration still capable of suppressing rice bacterial blight were 2 ${\mu}g$/ml and 16 ${\mu}g$/ml for bottromycin A2, and 64 ${\mu}g$/ml and 0.06 ${\mu}g$/ml for dunaimycin D3S, respectively. These two compounds were shown to exert different bioactivities in vitro and in rice leaf explants.

• The Plant Pathology Journal
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• v.34 no.5
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• pp.445-450
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• 2018

Bacteriophages, bacteria-infecting viruses, have been recently reconsidered as a biological control tool for preventing bacterial pathogens. Erwinia amylovora and E. pyrifoliae cause fire blight and black shoot blight disease in apple and pear, respectively. In this study, the bacteriophage phiEaP-8 was isolated from apple orchard soil and could efficiently and specifically kill both E. amylovora and E. pyrifoliae. This bacteriophage belongs to the Podoviridae family. Whole genome analysis revealed that phiEaP-8 carries a 75,929 bp genomic DNA with 78 coding sequences and 5 tRNA genes. Genome comparison showed that phiEaP-8 has only 85% identity to known bacteriophages at the DNA level. PhiEaP-8 retained lytic activity up to $50^{\circ}C$, within a pH range from 5 to 10, and under 365 nm UV light. Based on these characteristics, the bacteriophage phiEaP-8 is novel and carries potential to control both E. amylovora and E. pyrifoliae in apple and pear.