• Research in Plant Disease
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• v.14 no.1
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• pp.68-70
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• 2008

Brown leaf spots on leaves of kiwifruit(Actinidia deliciosa) were observed at farmers' orchards in Suncheon and Goheung, Jeonnam Province, Korea in June, 2006. They developed to form dark brown ring spots and severely infected leaves resulted in defoliation during the growing season of kiwifruit. Alternaria sp. was isolated from the diseased leaves repeatedly and was identified as Alternaria alternata on the basis of its mycological characteristics on potato dextrose agar and its pathogenicity was confirmed by wound inoculation on healthy leaves of kiwifruit. A. alternata formed gray to dark sooty gray colony and produced numerous conidia on potato dextrose agar. The conidia, commonly in long chains of 5 or more produced on conidiophores, have $3{\sim}5$ transverse and $1{\sim}2$ longitudinal septa and mostly ovoid or obclavate in shape and were pale brown golden brown in color. The condia were $16.5{\sim}42.1{\times}6.7{\sim}19.5\;{\mu}m$ in size and conidiophores were $8.6{\sim}112.7\;{\mu}m$ in length. This is the first report on the brown ring spot on leaves of kiwifruit caused by A. alternata in Korea.

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

• Research in Plant Disease
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• v.19 no.4
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• pp.300-307
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• 2013

This study was conducted to determine the occurrence of leaf rot and leaf ring spot, caused by Rhizoctonia solani in Chinese cabbage under seedling nursery and cultivation greenhouses. Symptoms of leaf rot and leaf ring spot were found in three Chinese cabbage cultivars, Brassica campestris subsp. pekinensis, 'Ryeokgwang', 'Daetong', and 'CR mat'. In Hwacheon, the disease incidence was 73.8% in the seedling stage of the Chinese cabbage. In Icheon, the symptoms were observed on the upper leaves of the Chinese cabbage cultivar, 'Norangmini' with 20.5% of disease incidence. The symptoms appeared as primary lesions consisting of small, circular necrotic ring spots with gray color, 1.4-3.0 mm in diameter, accompanied by secondary rot lesions with large irregular borders of leaves. The color of mycelial mat of 20 isolates was dark brown and light brown. The average hyphal diameter of all the isolates was within 5.01-11.12 ${\mu}m$. Among the 20 strains isolated from Chinese cabbage, 16 isolates and four isolates anastomosed with the AG-1 (IB) and AG-1 (IC), respectively. Twenty isolates tested were only virulent on foliage parts of Chinese cabbage leaves but were avirulent on stem parts of the plants. Based on the mycological characteristics and pathogenicity test on host plants, the fungus was identified as Rhizoctonia solani.