• The Korean Journal of Mycology
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• v.49 no.4
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• pp.539-545
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• 2021

A cercosporoid fungus associated with angular leaf spots on the leaves of common fig (Ficus carica) in Korea is known to be morphologically similar to Passalora, but phylogenetically similar to Pseudocercospora. To clarify the ambiguity, six fig samples with angular leaf spots were collected and examined using a microscope, and two representative isolates were sequenced for multiple genes. The morphological characteristics were consistent with previous descriptions of Passalora bolleana. Molecular phylogenetic analysis based on the internal transcribed spacer and large subunit ribosomal DNA (rDNA) regions showed that the Korean isolates, as well as previously published Korean and Romanian isolates, formed a well-supported group in the clade of Pseudocercospora species. Consequently, the current Korean isolates should be correctly described as Pseudocercospora bolleana. Additionally, Pseudocercospora fici-caricae, a cercosporoid fungus previously described as a leaf pathogen on common fig in Taiwan and Korea, was also compared and discussed.

• Research in Plant Disease
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• v.22 no.1
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• pp.9-17
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• 2016

Nationwide survey for angular leaf spot (ALS) of strawberry caused by Xanthomonas fragariae, a quarantine disease in Korea, was performed in November 2012. In the survey, ALS was observed in eighty eight farmers' fields of Sukok, Jinju and Okjong, Hadong in Gyeongnam Province, and one field in Namwon of Jeollabuk Province. The infected field of Namwon closed immediately after the disease diagnosed ALS. In detailed survey of Sukok and Okjong areas during February 2012 to January 2015, ALS occurrence decreased from 45% farmer's fields on December 2012 to 5% on January 2015, and from 38% on November 2013 to 5% on January 2015, respectively. Phenotypic characteristics of the Korean strains were similar to those of the type strain of X. fragariae. A multilocus sequence analysis of Korean strains of X. fragariae was conducted using four genes; dnaK, fyuA, gyrB, and rpoD. All the Korean strains had the same sequences of the four genes. The concatenated sequences of the Korean strains shared 100% with that of the type strain of X. fragariae. All strawberry cultivars tested were susceptible to the strains of X. fragariae two weeks after inoculation. The inoculated sites were necrosis and expanded, which were rated 4 based on evaluation of inoculation site.

• The Korean Journal of Mycology
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• v.48 no.3
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• pp.329-335
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• 2020

From 2008 to 2017, Korean azalea (Rhododendron yedoense f. poukhanense) showing angular, necrotic leaf spots were found in Jeju and Hongcheon, Korea. The lesions occurred frequently, detracting from the beauty of the glossy green leaves of the plant and causing premature defoliation. Therefore, to identify the fungus associated with the lesions, morphological characterization and molecular phylogenetic analysis of actin (Act), translation elongation factor 1-alpha (EF), internal transcribed spacer (ITS), 28S nrDNA (LSU), and RNA polymerase II encoding the second largest subunit (RPB2) of the two representative isolates were performed. The phylogenetic tree inferred from the neighbor-joining method showed the isolates clustering in the Sphaerulina azaleae group. Therefore, the fungus associated with the angular leaf spots on the Korean azalea was identified as Sphaerulina azaleae.

• The Korean Journal of Mycology
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• v.50 no.2
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• pp.131-136
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• 2022

Cornus officinalis plants that grow in several locations in Korea have been found to be infected with leaf spot disease. Symptoms include necrotic lesions, which are angular, irregularly shaped, vein-limited, and dark brown, on both sides of the leaves. The causal agent of the disease was identified to be Pseudocercospora cornicola based on the morphological characteristics of the fungus and molecular phylogenetic analysis of the obtained multi-locus DNA sequence data. This is the first report investigating P. cornicola found on C. officinalis in Korea.

• Research in Plant Disease
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• v.8 no.2
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• pp.78-83
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• 2002

Tobacco diseases have not been recorded until 1900s in Korea, where tobacco plants were introduced at early 1700s. Practical researches on the disease have been conducted since mid 1960s. Major ten tobacco diseases were mosaic caused by tobacco mosaic virus·potato virus Y·cucumber mosaic virus, bacterial wilt, hollow stalk, wild fire caused by angular leaf spot strain, black shank, brown spot, powdery mildew and fusarium wilt. But their annual occurrences were varied according to changes of tobacco varieties and their cultivating practices. As no useful chemicals, several biological tactics have been developed to control the viral or bacterial diseases that give significant economic damages on sustainable crop yield, but not practicable to field farming condition yet. Transgenic tobacco plants containing foreign disease resistant genes have been developed by current bio-technology, but not released to farmers yet. Though some disease-resistant tobacco varieties have been developed by the conventional breeding technology and currently used by farmers, their disease controlling efficacy have been diminished by occurrence of the new strain or race. Future research on tobacco diseases has been focused on technical development to produce high quality tobacco with less production cost, which leads Korean tobacco industry to keep its competence against foreign industry and decreasing overall market.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.47-53
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• 2015

Various diseases occur in fruits, leave and roots during strawberry cultivation and cause severe economical damage and huge amount of chemical fungicide use. Recently, as consumers' interest in safety of foods and organic agriculture produces have increased, control measures using alternatives for chemical fungicides have been newly developed in various ways. This study was conducted to test antifungal activity and control effect of sodium dichloroisocyanurate (NaDCC), using as disinfectants, against major disease pathogens of strawberry, Fusarium oxysporum (Fusarium wilt), Colletotrichum gloeosporioides (Anthracnose) and Phytophthora sp. (Phytophthora blight), and Xanthomonas fragariae (bacterial angular leaf spot) and evaluate availability as environment-friendly materials. When NaDCC was treated at the concentration range of 150 to 300 ppm, it suppressed significantly hyphal growth and reduced spore germination by more than 28%. In field condition, NaDCC showed excellent control effect (control value: 50%) against the bacterial angular leaf spot disease. Based on above-described results, we suggested that NaDCC can be used as alternative candidates to chemical pesticide alternatives of for controlling strawberry diseases.

• Journal of the Korean Society of Tobacco Science
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• v.15 no.1
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• pp.15-25
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• 1993

The severities of major tobacco diseases had been surveyed throughout northern Kyeongbuk, a major flue-cured tobacco growing district in Korea, in relation to the actual control method used by the farmers in 1992. At seedling stage, anthracnose caused by Colletotrichum nicotianae was major disease of the plant due to poor damage of the temporary transplanting pots. Mosaic caused by tobacco mosaic virus(TMV) was very severe in certain of greenhouses. Although viral disease caused by TMV, cucumber mosaic virus(CMV) and by potato virus Y(PVY) were severe in fields, but mosaic by TMV was major of the diseases. Potato virus Y was found later than that in Honam district. The late occurrence of the disease might be caused the difference between cultivating method of potato plants in northern Kyeongbuk and that in Honam district. In fields suffered from hail disaster, the damage of tobacco plants by angular leaf spot was severe. Most of tobacco growers had wrong information about the practical methods not only of milk treatment for the protection of the plants from TMV, but also of fungicide applications for the control of other major diseases. It suggested that education on the methods to the farmers must be very important for control of the diseases.

• Korean journal of applied entomology
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• v.53 no.2
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• pp.157-169
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• 2014

Between 2010 and 2012, diseases and insect pests of sweet persimmon were surveyed at sweet persimmon export complexes and non-export orchards in Suncheon, Jeonnam Province; Jinju, Changwon (Dongeup and Bukmyeon), and Gimhae, Gyeongnam Province; and Ulzu, Ulsan. The following diseases were found in the sweet persimmon orchards: angular leaf spot (Cercospora kaki), anthracnose (Colletotrichum gloeosporioides and Colletotrichum acutatum), circular leaf spot (Mycosphaerella nawae), powdery mildew (Phyllactinia kakicola), and gray mold (Botrytis cinerea). Circular leaf spot was the most frequent and serious disease, and C. gloeosporioides and C. acutatum were found on fruits. Thirty-three insect pest species that belonged to 32 genera of 20 families in 5 orders were found in the sweet persimmon orchards; the two-spotted spider mite, Tetranychus urticae, was also found in the surveyed orchards. Apolygus spinolae, Pseudaulacaspis cockerelli, and Adoxophyes orana were widely found in the surveyed orchards; Spodoptera litura and Homona magnanima were also recorded. Damage by insect pests was low, and the quarantine insect pests peach pyralid moth (Dichocrocis punctiferalis) and persimmon fruit moth (Stathmopoda masinissa) were rarely or not found in the sweet persimmon export complexes. In addition, other quarantine insect pests, such as persimmon false spider mite (Tenuipalpus zhizhilashviliae) and Japanese mealybug (Planococcus kraunhiae), were not detected. These quarantine insect pests were also not found in the sorting places, storage houses, and fruits for export; however, scale insects and two-spotted spider mites were found at a low rate. Although anthracnose (C. acutatum) infested fruit was found in the storage houses, only one in Jinju and Gimhae.