• The Plant Pathology Journal
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• v.37 no.4
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• pp.329-338
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• 2021

Alternaria leaf blight is one of the most common diseases in watermelon worldwide. In Korea, however, the Alternaria species causing the watermelon leaf blight have not been investigated thoroughly. A total of 16 Alternaria isolates was recovered from diseased watermelon leaves with leaf blight symptoms, which were collected from 14 fields in Korea. Analysis of internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and RNA polymerase II second largest subunit (RPB2) were not competent to differentiate the Alternaria isolates. On the contrary, analysis of amplicon size of the histone H3 (HIS3) gene successfully differentiated the isolates into three Alternaria subgroups, and further sequence analysis of them identified three Alternaria spp. Alternaria tenuissima, A. gaisen, and A. alternata. Representative Alternaria isolates from three species induced dark brown leaf spot lesions on detached watermelon leaves, indicating that A. tenuissima, A. gaisen, and A. alternata are all causal agents of Alternaria leaf blight. Our results indicate that the Alternaria species associated watermelon leaf blight in Korea is more complex than reported previously. This is the first report regarding the population structure of Alternaria species causing watermelon leaf blight in Korea.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.245-248
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• 1994

Leaf blight of watermelon severely occurred up to 46% in fields at Hwaseong area in Korea during July, 1993. The causal fungus was identified as Alternaria cucumerina (Ellis et Everh.) Elliott. Pathogenicity tests revealed that all the three watermelon cultivars used were susceptible to leaf blight.

• The Plant Pathology Journal
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• v.27 no.2
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• pp.120-127
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• 2011

While many isolates of Alternaria alternata are common saprophytes on trees and shrubs, this study clearly demonstrated that A. alternata is a primary pathogen in lilac (Syringa sp.), causing a leaf-blight that affects different Syringa species. Isolates of Alternaria sp. were collected from leaf blight samples of lilacs in the field. The internal transcribed spacer (ITS) region and morphological characterization were used to identify lilac blight pathogen. Based on 100% ITS nucleotide sequence identities to the Alternaria genus in the GenBank and morphological features, these isolates were identified as A. alternata. Disease symptoms were reproduced in lilac plants inoculated with A. alternata mycelial plugs and sprayed with a fungus-free culture filtrate, indicating that pathogenesis in lilac involves secondary metabolites or toxins. Diagnostic primers were developed to detect Alternaria sp. and A. alternata in lilac leaf blight based on ITS region and four known genes associated with pathogenesis in A. alternata: mixed-linked glucanase precursor, endopolygalacturonase, hsp70, and histone genes. The results from our study indicated A. alternata is a primary pathogen in lilac leaf blight, and these diagnostic primers can be used as a tool for the fast detection of A. alternata associated with lilac leaf blight.

• Korean Journal of Medicinal Crop Science
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• v.21 no.5
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• pp.388-393
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• 2013

This study was conducted to select environmental friendly organic materials for controlling the ginseng alternaria blight and to evaluate their effects from 2011 to 2012. Alternaria blight is caused by Alternaria panax and is the most common ginseng disease in Korea. Environmental friendly organic materials were used to reduce amount of chemical fungicides and the number of spray for control of Ginseng Alternaria leaf blight. In 4 years of ginseng, control value of Alternaria leaf blight by single application of Defenoconazole WP was 82.3% and those of single application was 62.0~75.9%. Consequently, mixed or alternated application of eco-material products could be recommended as a control method to reduce the amount of fungicides.

• Mycobiology
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• v.38 no.4
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• pp.316-320
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• 2010

Leaf spot and blight disease was observed on two-year-old seedlings of Dendropanax morbifera (Korean name: Hwangchil tree) during July of 2008 in Jindo Island, Korea. Symptoms included yellow-brown to dark brown irregularly enlarged spots frequently located along the veins of leaves. The lesions were often surrounded by chlorotic haloes. Severe leaf blight and subsequent defoliation occurred when conditions favored disease outbreak. The causal organism of the disease was identified as Alternaria panax based on morphological characteristics and sequence analysis of the internal transcribed spacer region of rDNA. A. panax isolates induced leaf spots and blight symptoms not only on D. morbifera but also on the other members of Araliaceae tested. This is the first report of foliar blight caused by A. panax on D. morbifera.

• Journal of agriculture & life science
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• v.50 no.4
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• pp.249-253
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• 2016

Aster glehni Franchet et Schmidt is a compositae plant and has been known as a native specie in Ulleung Island, Korea. It is officially recognized as a regional specialty that grows only in this region. In 2014, brown and dark spots were observed on aster leaves in a forest research field, Jinju, Korea. A causal agent was isolated from the disease symptomatic leaves and identified as fungus Alternaria solani. Fungal morphological characteristics and molecular identification with internal transcribed spacer sequences were synchronized as A. solani. The isolated fungi reproduced the same disease symptoms when the fungus was artificially inoculated on healthy aster leaves. This is the first report that A. solani caused leaf blight disease in Aster glehni in Korea.

• The Plant Pathology Journal
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• v.33 no.6
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• pp.543-553
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• 2017

Sesame (Sesamum indicum) is an important oil seed crop of Asia. Yields can be negatively impacted by various factors, including disease, particularly those caused by fungi which create problems in both production and storage. Foliar diseases of sesame such as Alternaria leaf blight may cause significant yield losses, with reductions in plant health and seed quality. The work reported here determined the incidence of Alternaria species infecting sesame seeds grown in the Punjab, Pakistan. A total of 428 Alternaria isolates were obtained from 105 seed samples and grouped into 36 distinct taxonomic groups based on growth pattern and morphological characters. Isolation frequency and relative density of surface sterilized and non-surface sterilized seeds showed that three isolates (A13, A47 and A215) were the most common morphological groups present. These isolates were further identified using sequencing of the Internal Transcribed Spacer (ITS) region of ribosomal DNA (rDNA) and the Alternaria major allergen gene (Alt a 1). Whilst ITS of rDNA did not resolve the isolates into Alternaria species, the Alt a 1 sequences exhibited > 99% homology with Alternaria alternata (KP123850.1) in GenBank accessions. The pathogenicity and virulence of these isolates of Alternaria alternata was confirmed in inoculations of sesame plants resulting in typical symptoms of leaf blight disease. This work confirms the identity of a major source of sesame leaf blight in Pakistan which will aid in formulating effective disease management strategies.

• The Plant Pathology Journal
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• v.31 no.1
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• pp.78-82
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• 2015

In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus) leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

• 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.

• Research in Plant Disease
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• v.14 no.2
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• pp.102-106
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• 2008

The single application of Bacillus subtilis QST713(BS QST713) mixed application with fungicides and alternate application were treated to examine the control of alternaria leaf blight of Panax ginseng. Control value of alternaria leaf blight by single application of BS QST713 at 10 days interval was 83.3%, and those of single application at 10 days interval was $80.4{\sim}83.7%$ by azoxystrobin, chlorothalonil copper sulfate basic, copper sulfate basic, kresoxim-methyl, difenoconazole, mancozeb. When mixture of BS QST713 and fungicides were applied at 14 days interval, the control value of alternaria leaf blight were 83.6% by BS QST713 and mancozeb, and 82.6% by BS QST713 and azoxystrobin. However, mixture of BS QST713 with difenoconazole, kresoxim-methyl, copper sulfate basic and chlorothalonil copper sulfate basic exhibited the disease control values from 61.1% to 76.4%, which showed slightly lower control efficacy. In Daejeon, the alternate application of BS QST713 followed by copper sulfate basic with 14 days interval was 85.9% in control value, which showed the best control efficacy. The alternate application with other tested fungicides slightly decreased to $55.5{\sim}78.2%$ in control value. However, the alternate application of BS QST713 followed by fungicides showed very high control efficacy, which were approximately 90% in Muju, Jeonbuk Province. Consequently, the single, mixed or alternate application of BS QST713 and fungicides could be recommended as a control method to reduce the amount of fungicides.