• Korean journal of applied entomology
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• v.24 no.2 s.63
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• pp.103-106
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• 1985

The present study was carried out to determine appropriate growth stage for evaluating resistance to septoria brown spot in field and to search resistance sources from soybean germ plasm. Disease severity expressed by log $\frac{x}{1-x}$ was different with soybean genotypes and vertical progress of the disease was related to the diseased leaf area. Correlation between diseased leaf area and the area under septoria brown spot disease progress curve (AUBC) was highest at full blooming stage, indicating a reasonable stage for measuring the disease severity to evaluate resistance in field. There was no lines highly resistant to the disease among 1,428 native soybean lines tested.

• Research in Plant Disease
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• v.9 no.3
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• pp.149-152
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• 2003

Black leaf spot disease occurred on Dendrobium phalaenopsis grown in farmer's fields located in Bonggangmyon, Gwangyang-eup, Jeonnam, Korea. Black small spots occurred on leaves at initial stage of infection and the infected leaves turned yellow from the tip. The yellow leaves were falled, resulting in stem blighting or eventual death of the entire plant. White mycelial colony of the causal fungus grown on potato dextrose agarturned dark violet later and optimum temperature for the mycelial growth was $25^{\circ}C$. The causal fungus isolated from the black leaf spot on D. phalaenopsis was identified as Fusarium moniliforme based on the mycological characteristics and pathogenicity. The fungus also caused same symptoms on leaves of Phalaenopsis sp. and Cymbidium sp. as well sa D. phalaenopsis by wound inoculation. This is the first report on black leaf spot of D. phalaenopsis caused by F.moniliforme in Korea.

• Korean journal of applied entomology
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• v.12 no.3
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• pp.121-124
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• 1973

From the new rice variety Tong-il, disease symptoms similar to Fusarium leaf spot reported in Japan was observed in Korea. Causal organism was isolated and identified as Fusarium nivale causing Fusarium leaf spot through the study of conidia shape, ascus formation on diseased spot, and ascospore. These results also showed good agreement with that of other investigators. Under the field condition, marked occurrence of this disease has observed by heavy nitrogen application. The optimum temperature for the growth of this fungus was $24^{\circ}C$.

• Research in Plant Disease
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• v.10 no.2
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• pp.121-125
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• 2004

An epidemic of target leaf spot of cucumber (Cucumis sativus) occurred in commercial greenhouses in Korea in 2000/2001. The early symptoms on the leaves were small brown spots with yellow halos. These lesions became irregular enlarging in diameter and eventually defoliation resulted. The causal agent was a fungus with morphological characteristics matching Corynespora cassiicola. The sequence of the ITS region of C. cassiicola CM2000-1 was identical to that of an authentic strain of Corynespora cassiicola. Optimal germination of spores and mycelial growth on plate was at 3$0^{\circ}C$. A long dew period on the leaf surface and high temperatures were the main contributing factors for disease development and the greenhouse epidemic. Artificial inoculation of the Korean isolate of C. cassiicola revealed resistance in some Korean cucumber cultivars.

• 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.

• Research in Plant Disease
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• v.15 no.3
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• pp.193-197
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• 2009

Pseudocercospora leaf spot was major disease of grape cultivar 'Campbell Early' in Korea. Leaf spot first appeared in early June and rapidly dispersed to other leaves through rainy season. Disease progress of leaf spot by Pseudocercospora vitis in plastic green house, in the two provinces (Gimje and Gimcheon), were investigated in 2007. Differences of Infected leaves (%) between cultivation systems were observed in field and plastic green house, but there was no difference between provinces. Micro environmental factors, such as temperature and relative humidity, were correlated with infected leaves by PROC REG procedure of SAS (Statistical Analysis System). As a result, regression model best described ($R^2=0.95^{**}$) the infected leaves as a function of the interaction of cumulated temperatures; Y (Infected leaves)=-7.0101+0.0496$\times$20Hcum (Cumulated hour above 20 degree)+0.0208$\times$20cum (Cumulated temperature above 20 degree)-0.2781$\times$25Hcum (Cumulated hour above 25 degree). A statistics model was shown that cumulated hour and temperature above specific degree were critical factor for Pseudocercospora leaf spot on the grapevine leaves in plastic green house.

• Korean Journal of Organic Agriculture
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• v.29 no.2
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• pp.257-273
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• 2021

Koreans consume cham-chwi (Aster scaber thunb.) as a common vegetable in a meal because of its bitter taste and rich flavor. In addition, it is the crop with the most residual pesticides detected in the last five years. Among the detected pesticides, the most common was azoxystrobin, which is a drug used primarily to prevent the leaf spot disease of A. scaber caused by Septoria sp.. We isolated the microorganisms that antifungal activity against Septoria sp.. The optimum incubation conditions (temperature, pH and growth medium) were examined for the growth of the isolates. Additionally, cellulase and protease activity and siderophore production ability were also examined. According to 16S rRNA sequencing of the isolate was affiliated to Paenibacillus polymyxa JE201. Largest inhibition zone measuring up to 9.2 mm was observed for P. polymyxa JE201 after 7 days of inoculation. P. polymyxa JE201 strain showed antifungal activity against various fungal phytopathogens Altanaria sp., Botrytis cinerea, Colletotrichum acutatum, Fusarium oxysporum, Phytophthora capsici, Ph. drechesleria, Rhizoctonia solani and Stemphylium sp.. Based on these observations, P. polymyxa. JE201 can be used as a promising biocontrol agent for preventing the leaf spot disease and other phytopathogens.

• Research in Plant Disease
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• v.21 no.3
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• pp.243-249
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• 2015

Soybean frogeye leaf spot caused by the fungus Cercospora sojina Hara, has known to lead a severe reduction of crop yield. Since frogeye leaf spot on soybean has recently become a serious problem in Korea, the susceptibility of recent recommended cultivars against C. sojina had been tested. To standardize the disease severity of soybean, the optimum sporulation condition of C. sojina and the disease index were established in this study. Sporulation was maximized on the 10% V8 juice agar with 12 h light and 12 h dark at $25^{\circ}C$. Spore suspension ($10^5spores/ml$) was sprayed on the leaves of soybean (V6 stage), and the disease responses to each isolate were evaluated on 28 days after inoculation. As a result, Daepung, Shinpaldal2ho, Yeonpung and Cheonga showed the resistance reaction to 8, 7, 6, 6 isolates of C. sojina, respectively, whereas Cheongja, Hwangkeum, Taekwang, Daewon, Cheonsang and Sinhwa showed the susceptible reaction to 8 isolates of C. sojina. Breeding the resistant soybean cultivars against C. sojina requires a uniform resistance for screening technique. The disease index of frogeye leaf spot on soybean developed in this study can be effectively used for the accurate field assay to select the frogeye leaf spot resistant soybean.

• Research in Plant Disease
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• v.8 no.2
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• pp.117-119
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• 2002

Leaf spot disease was found on broad bean (vicia faba) in several farmer's fields located in Changseon-myon, Namhae-gun, Gyeongnam province, Korea. The typical symptoms of the disease were appeared on leaves, stems and pods. The infection rates of the disease in the surveyed area were ranged from 8.4 to 46.8％. Colonies formed on PDA were developed aerial hyphae with grayish white, which later turned olive-green to black. Conidia were dark brown in color, long ellipsoid to elongated ovoid, obclavate and 23.7~61.3$\times$7.2~16.8 ${\mu}{\textrm}{m}$ in size. Septa were 4~10 transvers, 1~2 longitudinal or oblique. Conidiophores were solitary or fascicles and 18~113$\times$3~6 ${\mu}{\textrm}{m}$ in size. The optimum temperature for growth of the fungus was about 3$0^{\circ}C$. This is the first report on the leaf spot of broad bean caused by Alternaria tenuissima in Korea.

• Mycobiology
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• v.46 no.2
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• pp.168-171
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• 2018

In 2016, a severe leaf spot disease was found on Iris ensata Thumb. in Nanjing, China. The symptom was elliptical, fusiform, or irregularly necrotic lesion surrounded by a yellow halo, from which a small-spored Alternaria species was isolated. The fungus was identified as Alternaria iridiaustralis based on morphological characteristics. The pathogenicity tests revealed that the fungus was the causal pathogen of the disease. Phylogenic analyses using sequences of ITS, gpd, endoPG, and RPB2 genes confirmed the morphological identification. This study is the first report of A. iridiaustralis causing leaf spots on I. ensata in China.