• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.210-216
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• 1995

Alternaria spp.were predominantly isolated from the abnormal leaf spot lesions of pear cultivars Niitaka and Nijiiseiki. Alternaria isolates from the cultivar Niitaka were not pathogenic to both cultivars, but the isolates from the cultivar Nijiiseiki developed typical lesions of black leaf spots and were identified as A. kikuchiana. However, no typical abnormal leaf spot lesions were produced by the Alternaria isolates. Foliar spray of twelve different agrochemicals including lime sulfur, either alone or in combinations, with 7 times applications from April to July failed to reduced the disease development. Application of 17 different pesticides including fungicides, insecticides and herbicides currently used in pear orchards did not cause leaf injury similar to the abnormal leaf spot. Simulated acid rain of as low as pH 3.0 did not incite any leaf lesions alike the abnormal spot lesions. Mineral contents in the leaves of both cultivars did not differ significantly between the healthy leaves and those with abnormal leaf spots. When cuttings of pear tree were obtained in February from newly emerged twigs of the healthy or the diseased trees of Niitaka and planted in sand in the greenhouse, only those from the diseased trees developed typical leaf lesions of the abnormal spot. These results indicate that abnormal leaf spots are caused by unknown systemic agents in pear trees, rather than by Alternaria spp., chemical injury or acid rain.

• Mycobiology
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• v.42 no.4
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• pp.405-408
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• 2014

Leaf spot disease was observed in sesame (Sesamum indicum L.) during 2009 and 2010 in Korea. The pathogen was identified as Alternaria simsimi based on morphological and cultural characteristics. The morphological identification was well supported by phylogenetic analysis of the ribosomal DNA-internal transcribed spacer region. A. simsimi isolates caused spot symptoms on leaves and stems of sesame plants 2 wk after artificial inoculation, which were similar to those observed in the field. This is the first record of leaf spot disease in Korea caused by A. simsimi.

• Research in Plant Disease
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• v.10 no.2
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• pp.126-129
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• 2004

In July of 2002, leaf spot disease was found on kudzu (Pueraria lobata) leaves in Jeonbuk province. A small leaf spot was appeared on leaves as a typical symptom and the spot was then surrounded by chlorotic halo. The lesions were expended and coalesced and the infected leaves became yellow leaf and later fall out. A causal fungal pathogen was isolated and the colony of the pathogen was light gray green to dark green on PDA. The pathogen produced mostly the single conidium but rarely long chain of 3 to 8 conidia. The conidia were dark brown in color, long ellipsoid or oval and 20-60 ${\times}$ 10-25 ${\mu}{\textrm}{m}$ in size. Their septa were 4-8 transverse and 1-2 longitudinal or oblique. The pathogen was, therefore, identified as Alternaria tenuissima based on cultural and morphological characteristics. This is the first report on the leaf spot of kudzu caused by A. tenuissima in Korea.

• Research in Plant Disease
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• v.21 no.4
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• pp.330-333
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• 2015

In June 2013, we collected leaf spot disease samples of Datura metel from Gangneung, Gangwon Province, Korea. The symptoms observed were small circular to oval dark brown spots with irregular in shape or remained circular with concentric rings. We isolated the pathogen from infected leaves and cultured the fungus on potato dextrose agar. We examined the fungus morphologically and confirmed its pathogenicity according to Koch's postulates. The results of morphological examinations, pathogenicity tests, and the rDNA sequences of the internal transcribed spacer regions (ITS1 and ITS4), glycerol-3-phosphate dehydrogenase (G3PDH) and the RNA polymerase II second largest subunit (RPB2) gene sequence revealed that the causal agent was Alternaria tenuissima. To the best of our knowledge, this is the first report of leaf spot of D. metel caused by A. tenuissima in Korea as well as worldwide.

• Mycobiology
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• v.46 no.3
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• pp.278-282
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• 2018

Chrysanthemum coronarium is an economically important plant in Asia, and used medicinally, ornamentally and as a vegetable. In April 2017, leaf spot disease on C. coronarium was observed in Shiyan, Hubei, China. A single-spore isolate was obtained and identified based on morphology and sequence analysis using four regions (rDNA ITS, GAPDH, $EF-1{\alpha}$, and RPB2). The results indicated that the fungus is Alternaria argyranthemi. The pathogenicity tests revealed that the species could cause severe leaf spot and blight disease on the host. This is the first report of leaf spot disease on C. coronarium caused by A. argyranthemi in the world, which is also a new record of Alternaria species in China.

• Research in Plant Disease
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• v.27 no.3
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• pp.107-114
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• 2021

During a disease survey on weeds and minor cultivated crops in Korea, a brown leaf spot disease was observed on Sonchus asper. Leaf lesions were round or irregular in shape, and grayish brown to brown with a purple margin. In severe infection, lesions enlarged and coalesced, resulting in blighting of the leaves. The isolates from these leaf lesions were identified as Alternaira sonchi based on morphological characteristics and phylogenetic analyses of Internal transcribed spacer region, Alternaria allergen a1, glyceraldehyde 3-phosphate dehydrogenase, RNA polymerase II, and translation elongation factor genes. This study provides a comprehensive description of the morphological characteristics and phylogenetical traits of A. sonchi causing brown leaf spot on S. asper in Korea.

• 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.

• Mycobiology
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• v.44 no.3
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• pp.187-190
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• 2016

In July 2015, diseased leaves of black chokeberry (Aronia melanocarpa) were observed in Danyang and Gochang, Korea. The symptoms appeared as circular or irregular brown leaf spots, from which Alternaria tenuissima was isolated. The isolates were cultured on potato dextrose agar, and their morphological characteristics were observed under a light microscope. The colonies were whitish to ash colored. The pathogenicity test on healthy black chokeberry leaves produced circular brown spots, in line with the original symptoms. Molecular analyses of the ITS, GPD, RPB2, and TEF genes were conducted to confirm the identity of the pathogen. The phylogeny of the multi-gene sequences indicated that the causal agent was A. tenuissima. This study is the first report of A. tenuissima leaf spot on black chokeberry (A. melanocarpa).

• Research in Plant Disease
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• v.9 no.3
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• pp.159-161
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• 2003

Leaf spot diseases were found on safflower (Carthamus thinctorius) leaf in several fields located in Euisong-Gun, Gyengbuk province in Korea. The infected leaf rate of the diseases in surveyed area were different each years from 2001 to 2003 such as about 5%, 10%, and 30%, repectively. The typicla symptoms of diseases appeared first as small, light brown spots on leaves. And then spot turn dark brown and magnified. And yellow decoloration zone appeared surrounding dark brown spots. Mycological characteristics of Alternaria carthami, isolated from safflower mature leaf spot were dark gray colonies, conidiophores simple erect, septated, 40~80 ${\mu}m$ length; conidia solitary, straight, body size fo without beak length 40~100${\mu}m$, 10~15${\mu}m$ thick, Number of transverse septa 4~10 and longitudinal septa 4~7 ; beak with 2~4 septa, 30~65${\mu}m$ length. And A. alternata, isolated from old leaf were gray~dark gray colonies, conidiophores simple or branched, 20~110 ${\mu}m$ length; conidia long chaines, short conical or cylindrical beak, 2~6 transverse septa and several longitudinal septa, body size of without beak length 30~60 ${\mu}m$, 10~20 ${\mu}m$ thick ; beak length 5~35 ${\mu}m$. These are the first report on the leaf spot of safflower caused by Alternaria carthami, A alternata in Korea.

• Korean journal of applied entomology
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• v.26 no.4 s.73
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• pp.273-275
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• 1987

Changes in the numbers of air-borne spores of Alternaria mali causing the Alternaria leaf spot of apple were investigated in apple orchards, by monitoring their AM- toxin(host-specific toxin) producing ability. Most of the air-borne Alternaria in apple orchards were not AM-toxin producers. In culture, only about 2% of Alternaria isolates from a commercially managed apple orchards produced the toxin that was highly toxic only to susceptible leaves.