• Research in Plant Disease
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• v.8 no.4
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• pp.254-257
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• 2002

It was conducted to investigate an effective control measure of the black necrotic leaf spot disease on pear, The disease commonly occurred in major cultivation areas of Korea revealed 5.6 ％ infection rate on the widely growing cultivar Niikata. The disease substantially reduced yield and quality of pear fruits, however, it has never been controlled by chemicals. Renewal of the pear trees to resistant cultivar was found to be the most effective to control the disease. As a result, the disease did not developed for 2 years on the diseased Niikata that was top-grafted with resistant cultivars Soowhang and Whasan. lop-grafting with resistant cultivars was recommended far the pear trees showing over 80％ infection rate and lower than 70% fruit yield compare to standard production.

• The Plant Pathology Journal
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• v.36 no.2
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• pp.179-184
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• 2020

A leaf spot pathogen Alternaria sp. was recovered from jimson weed, tomato, parsley, and coriander collected during surveys of blight diseases on Solanaceae and Apiaceae in Algeria. This species produced large conidial body generating long apical beaks that tapered gradually from a wide base to a narrow tip and short conidiophores originating directly from the agar surface. This species exhibited morphological traits similar to that reported for Alternaria crassa. The identification of seven strains from different hosts was confirmed by sequence analyses at the glyceraldehyde-3-phosphate dehydrogenase, RNA polymerase second largest subunit, and translation elongation factor 1-alpha loci. Further the pathogen was evaluated on jimson weed, coriander, parsley, and tomato plants, and this fungus was able to cause necrotic lesions on all inoculated plants. A. crassa is reported for the first time as a new species of the Algerian mycoflora and as a new potential pathogen for cultivated hosts.

• Mycobiology
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• v.44 no.2
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• pp.93-98
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• 2016

A new leaf spot disease was observed on leaves of Rheum palmatum (Chinese rhubarb) in Northwest China (Gansu Province) starting in 2005. A Septoria-like fungus was isolated and completion of Koch's postulates confirmed that the fungus was the casual agent of the leaf spot disease. Morphology and molecular methods were combined to identify the pathogen. The fungus produced conidiomata pycnidia and the conidia were 2~5 septate, $61.2{\sim}134.1{\mu}m$ in length and $3.53{\sim}5.3{\mu}m$ in width, which is much larger than the known Spetoria species that infects Polygonaceae species. Phylogenic analysis of the internal transcribed spacer region confirmed that this Septoria-like fungus is within the Septoria genus but distinct from known Septoria species. Together, these morphological and phylogenetic data support that the R. palmatum infecting Septoria strain is a newly-described plant pathogenic species.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.2
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• pp.175-180
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• 2003

Changes in biochemical constituents and physiological alteration were studied in various intensities (1-5%, 6-15%, 16-30%, 31-50% and ＞ 50%) of leaf spot (Myrothecium roridum) on mulberry leaves and compared with healthy leaves. Chlorophyll, total soluble sugar and total protein were decreased (P ＜ 0.01), but total phenol increased due to pathogen infection. Changes in biochemical constituents showed significant correlation with intensity of disease. Chlorophyll ($r^2$= 0.92), and protein (($r^2$= 0.83) possessed negative while phenol (($r^2$= 0.61) possessed positive correlation. Photosynthetic rate, transpiration rate, stomatal conductance, moisture content (%) and physiological water use efficiency (pWUE) were decreased, but stomatal resistance increased in the infected leaves. Physiological parameters also possessed significant (P ＜ 0.01) correlation with disease intensity. Photosynthetic rate (($r^2$= 0.96), transpiration rate ($r^2$=0.88), stomatal conductance (($r^2$= = 0.65), physiological water use efficiency (($r^2$= 0.88) and moisture content (r = 0.85) were negatively but stomatal resistance (($r^2$= 0.75) was positively correlated to disease intensities.

• The Plant Pathology Journal
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• v.33 no.4
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• pp.434-439
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• 2017

Incidence rates of diseases in kiwiberry orchards were investigated monthly from late June to late September in Gwangyang and Boseong in 2015 and 2016. The impact of postharvest fruit rot was investigated during ripening after harvest. Bacterial canker was only observed on one single tree in 2015, but black rot, powdery mildew, leaf spot and blight, and postharvest fruit rot diseases were problematic throughout the study period in both 2015 and 2016. Incidence rates of the diseases varied with kiwiberry cultivar, region and sampling time. Incidence rates of powdery mildew, leaf spot and blight diseases increased significantly during the late growing stages near fruit harvest, while black rot peaked in late August. Incidence rate of postharvest fruit rot on fruit without fruit stalks was less than half of fruit with fruit stalks, regardless of kiwiberry cultivars. Among the four cultivars, Mansu was relatively resistant to black rot and postharvest fruit rot diseases. In our knowledge, this is the first report of various potential pathogens of kiwiberry 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.

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

• Journal of Plant Biology
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• v.4 no.1
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• pp.21-24
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• 1961

The strains of fungus which belong to Coniothyrium genus were isolated from leaf spoot of Yucca. The isolated strain can grow easily and forms characteristic colonies on Saido's soy agar. There are definite differences, according to other authors, (By Miyake et Hara 1911) Pycnidio-spore are usually formed ellipsoidal, dark brown, 4$\times$2. 5-4. $O\mu$ in size, whereas isolated strains are globose, yellowish brown, 2.8-4.2$\mu$ in diameter. The positive inoculation test can be attained by burned petridish method, preserving it in incubator at 28$^{\circ}C$, and the pycnidio-spore can be reisolated from the inoculated portion. (Photo.7) Up to the present day there is no report for leaf spot of Yucca caused by Coniothyrium sp.. Comparing the writer's isolate with those fungi described(leaf spot of alloe, rose canker and elm canker etc.) hitherto, there are no accordance in the symptom and especially in morphological charactgers and Pathogenicitys.

• Research in Plant Disease
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• v.28 no.2
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• pp.57-60
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• 2022

Leaves of Chionanthus retusus were found to be damaged by leaf spot disease associated with a fungus in Iksan, Korea. Leaf spots were angular to irregular, vein-limited, scattered, 1-8 mm diameter, brownish-gray to dark brown when dry, with heavy fructification. The pathogen causes premature defoliation of C. retusus plant and was identified as Pseudocercospora chionanthi-retusi based on morphological and molecular-phylogenetic analyses. The phylogenetic tree was constructed using multi-locus DNA sequence data of partial actin (actA), partial translation elongation factor 1-alfa (tef1), partial DNA-directed RNA polymerase II second largest subunit (rpb2) genes, and internal transcribed spacer regions. Current study provides detail morphological description of P. chionanthi-retusi on C. retusus in Korea, with supports of phylogenetic analysis and pathogenicity test.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.3
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• pp.199-203
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• 2006

In the late growth stage of rice plant, the growth declines even though they grow well in early growth stage. This phenomenon is called autumn declining and it often accompanies the infection of Helminthosporium leaf spot disease. This study was carried out to identify the related environmental factors and to establish the integrated control system of Helminthosporium Leaf Spot Disease in rice. The total area of infected paddy field by Helminthosporium leaf spot was 470 ha in 2000 and 1,004 ha in 2001, which occupied about 1% of the total paddy area in Gyeongbuk province, Korea. The ill-drained sandy paddy occupied 50% of the total area of infected paddy fields and followed by sandy paddy (28%). Comparing the content of soil elements between infected and normal paddy, it was clarified that the organic matter content of normal was higher than that of infected paddy and the contents of inorganic elements such as Mn, Fe, Zn and available $SiO_2$ were also higher in normal paddy. The results of comparing the inorganic elements between infected and normal rice plants also showed the same results. The contents of inorganic elements such as MgO, $SiO_2$, Fe, Mn were higher in normal rice plants. Especially highly significant difference of $SiO_2$ content on both soil and rice plants was noticeable.