• The Plant Pathology Journal
• /
• v.24 no.2
• /
• pp.125-130
• /
• 2008

Various kinds of leaf spots and blights were found in kiwifruit (Actinidia deliciosa) orchards on 2006 in Korea. Disease incidences were quite variable between open-field and rain-proof shelter. Rate of diseased leaves was recorded as about 70% at open-field orchards in late season but use of rain-proof vinyl shelters alleviated the disease incidences by 20%. Angular leaf spots appeared at early infection stage on June and several other symptoms were also recognized as the disease developed afterward. On September, brown leaf blights were the most frequent, followed by grayish brown ring spots, silvering gray leaf blights, zonate leaf blights, dark brown ring spots and angular leaf spots at open-field orchards. Four fungal species were frequently isolated from the disease symptoms. Phomopsis sp. was the most predominant fungus associated with the leaf spot and blight symptoms on kiwifruit, followed by Glomerella cingulata, Alternaria alternata and Pestalo-tiopsis sp. Phomopsis sp. was commonly isolated from angular leaf spots, silvering gray leaf blights, and zonate brown leaf blights. G. cingulata, A. alternata and Pestalotiopsis sp. were isolated from grayish brown ring spots (anthracnose), brown ring spots and zonate dark brown leaf blights. Typical symptoms appeared on the wounded and unwounded leaves, which were inoculated by each of Phomopsis sp., G. cingulata, and Pestalotiopsis sp., but A. alternata caused symptoms only on the wounded leaves.

• Korean Journal Plant Pathology
• /
• v.11 no.3
• /
• pp.210-216
• /
• 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
• /
• v.45 no.2
• /
• pp.114-118
• /
• 2017

In September 2013 and 2014, a significant number of kenaf plants showing symptoms of leaf spots with approximately 50% incidence were found in experimental plots in Iksan and Namwon, Korea. Leaf spots were circular to irregular, more or less vein-limited, reaching to 10 mm in diameter. The spots were initially uniformly brown to reddish brown, turning pale brown with a purplish margin and showing grayish patches on the lesion due to heavy fructification. The causative agent of the leaf spot disease was identified as Cercospora malayensis. The pathogenicity test was conducted with similar results, which fulfilled Koch's postulates. This is the first report of C. malayensis infection of kenaf in Korea.

• The Korean Journal of Mycology
• /
• v.47 no.3
• /
• pp.271-274
• /
• 2019

Between August and September 2017, zonate leaf spots with severe defoliation were observed on Parthenocissus tricuspidata in Gimcheon, Korea. The initial symptoms included water-soaked, gray to grayish brown, circular or irregular-shaped leaf spots. As the disease progressed, the spots enlarged, coalesced, and became cream-colored with characteristic target-shaped rings, leading to leaf blight and premature defoliation. Based on cultural and morphological characteristics, the fungus associated with the symptoms was identified as Grovesinia moricola. The identity of this fungus was confirmed by analyzing sequences of the internal transcribed spacer region of ribosomal DNA. The pathogenicity of the isolate was demonstrated by artificial inoculation. To our knowledge, this is the first report of G. moricola occurring on P. tricuspidata globally as well as in Korea.

• Korean Journal Plant Pathology
• /
• v.11 no.3
• /
• pp.217-223
• /
• 1995

Nature of graft transmissibility of pear abnormal leaf spot disease was examined by various grafting methods in the greenhouse and field. When the diseased and symptomless twigs were collected in winter and grafted in the next spring to the seed-originated healthy root stock, the abnormal leaf spot was developed only in the case of the diseased twigs. Double grafting on a seed-originated healthy root stock, where the diseased and the symptomless twigs were used as 1st and 2nd scions, respectively, developed abnormal leaf spot lesions without exception on the 2nd scions. Tongue-graft with the diseased and the symptomless trees also incited abnormal leaf spots on the both trees. Abnormal leaf spots of were also developed on HN-39, an indicator pear tree, used as a 2nd scion in a double graft test, where the diseased twig and a seed-originated healthy tree were used as the 1st scion and the root stock, respectively. When the diseased twig was top-grafted to the healthy root stock, lesion development of abnormal spot was limited to the grafted twig itself in the 1st year, but expanded to the main branches in the 2nd year, and spread over the whole tree in the 3rd year. This result indicates that the causal agent of abnormal leaf spot disease is transmitted by graft.

• The Plant Pathology Journal
• /
• v.15 no.4
• /
• pp.242-246
• /
• 1999

Gloeocercospora sorghi caused the zonate leaf spot on sorghum (Sorghum bicolor Moench) in fields in Korea. The zonate spots were conspicuous on sorghum leaves as circular, reddish purple bands alternating with tan or straw-colored areas, which formed a coarsely zonate pattern. The lesions often occurred in semicircular patterns along the margin of leaves. The fungus produced sporodochia on the surface of infected leaves in a moist chamber. The conidia, born in a pinkish to salmon-colored slimy matrix, were hyaline, elongate to filiform, straight or slightly curved, 3- to 17-septate, and of variable lenght (28-197 x 1.6-$3.4\mu\textrm{m}$). G. sorghi isolated from diseased leaves of sorghum caused characteristic reddish-brown water-soaked leaf spots when inoculated to seedlings.

• Mycobiology
• /
• v.45 no.1
• /
• pp.39-43
• /
• 2017

Leaf spot disease on black chokeberry (Aronia melanocarpa) was observed at several locations in Korea during 2014-2015. Leaf spots were distinct, scattered over the leaf surface and along the leaf border, subcircular to irregular and brown surrounded by a distinct dark color, and were expanded and coalesced into irregularly shaped lesions. Severely infected leaves became dry and fell off eventually. The causative agent was identified as Pseudocercospora pyricola. Morphological observations and phylogenetic analyses of multiple genes, including internal transcribed spacer, translation elongation factor 1-alpha, actin, and the large subunit ribosomal DNA were conducted. The pathogenicity test was conducted twice yielding similar results, fulfilling Koch's postulates. To our knowledge, this is the first report on P. pyricola infection of A. melanocarpa globally.

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

• Korean Journal Plant Pathology
• /
• v.10 no.4
• /
• pp.336-338
• /
• 1994

In 1991, the leaf brown spot of ivy-aureus (Scindapsus aureus) was found in Taejon and Seoul, Korea. The symptoms were appeared as dark-brown spots. The lesions were often surrounded by yellowish halos. These spots were enlarged to circular or elliptical in shape and dark-brown to black in color with slightly elevated in margin and sunken in center. The pathogenic bacteria were isolated from the diseased leaf of ivy-aureus were identified as Erwinia chrysanthemi on the basis of bacterial characteristics therefore, we would like to propose to the name of ivy-aureus disease caused by E. chrysanthemi as“bacterial brown rot of ivy-aureus”hereafter.

• Korean Journal Plant Pathology
• /
• v.14 no.6
• /
• pp.732-734
• /
• 1998

Leaf spot of Amelanchier asiatica was observed in Korea.. The major symptoms of the disease were small necrotic spots and severe early defoliation. On the basis of morphological characteristics of the fungus observed from naturally infected leaves, the causal organism was identified as Entomosporium mespili (DC. : Duby) Sacc. The conidial suspension prepared from sporulating lesions was sprayed on healthy leaves with or without wounding to prove pathogenicity of the fungus. Small spots were noticed tow days after inoculation, and acervuli containing numerous conidia were observed 7 and 10 days after inoculation from wounded and unwounded leaves, respectively. This is the first record of the disease on A. asiatica in Korea.