• The Plant Pathology Journal
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• v.30 no.3
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• pp.316-322
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• 2014

Recently, a Cucumber mosaic virus (CMV) strain, named as CMV-209, was isolated from Glycine soja. In this study, symptom expression of CMV-209 was analyzed in detail in Nicotiana benthamiana by comparing with that of CMV-Fny, which is a representative strain of CMV. Using infectious cDNA clones of CMV strains 209 and Fny, symptom expression of various pseudorecombinants between these two strains were examined in the early and late infection stages. In the early infection stage, the pseudorecombinants containing Fny-RNA2 induced stunting and leaf distortion on the newly emerged leaves whereas the pseudorecombinants containing 209-RNA2 caused no obvious symptoms. In the late infection stage, the pseudorecombinants containing 209-RNA1 and Fny-RNA2 induced severe leaf distortion and stunting, while CMV-209 induced mild symptom and CMV-Fny caused typical mosaic, general stunting, and leaf distortion symptoms, indicating that RNA 2 encodes a symptom determinant(s) of CMV, which is capable of enhancing symptoms. Furthermore, our results support the possibility that natural recombination between compatible viruses can result in emergence of novel viruses causing severe damages in crop fields.

• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.90-93
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• 1995

Leaf blotch of Welsh onion was observed at a farmer's field at Kangnung in July 1990. Further collection o the diseased materials was made in 1993 and 1994. The symptom initially appeared as discolored spot and later yellowish blotch with the long axis parallel to the leaf veins, which turned to sooty colored concentric lesion due to heavy production of conidiophores and conidia. Cladosporium allii-cepae (Ranojevic) M. B. Ellis was repeatedly isolated from the leaf lesions. Healthy Welsh onion inoculated with conidial suspension of the fungus produced the typical symptom 10 days after inoculation. Koch's postulates were fulfilled by reisolation of the fungus. This is the first report of a Cladosporium leaf blotch of Welsh onion in Korea.

• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.1
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• pp.21-28
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• 2006

Peroxidase activity was measured in brown leaf spot pathogen (Myrothecium roridum) inoculated potted mulberry (Morus alba) during pre-symptomatic to various symptom development stages and compared with corresponding healthy leaf tissues. The enzyme showed a pH optimum of 7.0 and the activity was linearly increased up to 15 min of incubation. The peroxidase had a broad substrate specificity and the rates of oxidation were in the rank of pyrogallol> guaiacol> ascorbate at pH 7.0. Catechol at 10 mM inhibited 89% of guaiacol-peroxidase and 76% pyrogallol-peroxidase activities, indicated higher non-specific peroxidation in pyrogallol dependent assay system in mulberry than guaiacol. The optimum requirement for the guaiacol dependent assay was 0.2 ml (${\approx}40-60{\mu}g$ equivalent of protein) of crude enzyme source. Excepting the 8th leaf from the apex, the peroxidase activity did not vary appreciably in different leaf positions. In pre-symptomatic phases, an initial (1 to 5 min) rise of peroxidase activity was noticed in inoculated leaves, and then maintained a plateau up to 300 min. In contrary, non-infected tissue showed a slightly increased trend of enzyme level up to 420 min. In infected tissue, a sharp transient increase (3.1 fold) of peroxidase activity appeared between 300 - 420 min post infections. Afterwards, significantly different but steady maintenance of enzyme levels were observed in two treatments. On the other hand, during symptom development, a sharp increase in peroxidase activity was noticed up to 4th grade of lesion appearance (25.1 % to 50% of leaf area infection), and then declined slightly. However, in non-infected but same age healthy leaves, such huge fluctuations of enzyme level did not apparent. A high positive correlation $(R^2=0.92)$ between peroxidase activity and leaf spot development grades was also marked. The result implies that pre-symptomatic burst (between 1 - 5 and 300 - 420 min) and subsequent increased trend of guaiacol peroxidase activity may require for the symptomatic manifestation of Myrothecium leaf spot in mulberry.

• Mycobiology
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• v.47 no.4
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• pp.408-414
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• 2019

Crinum asiaticum and Hymenocallis littoralis, commonly known as spider lilies are bulbous perennial and herbaceous plants that widely planted in Malaysia as ornamental. During 2015-2016, symptom of leaf blight was noticed on the hosts from several locations in Penang. The symptom appeared as irregular brown to reddish lesions surrounded by yellow halos. As the disease progressed, the infected leaves became blighted, dried, and fell off with the presence of black microsclerotia and pycnidia on the lesions parts. The present study was conducted to investigate the causal pathogen of leaf blight on C. asiaticum and H. littoralis. Based on morphological characteristics and DNA sequences of internal transcribed spacer (ITS) region and translation elongation factor 1-alpha (TEF1-α) gene, the causal pathogen was identified as Macrophomina phaseolina. Phylogenetic analysis of combined dataset of ITS and TEF1-α grouped the isolates studied with other isolates of M. phaseolina from GenBank. The grouping of the isolates was supported by 96% bootstrap value. Pathogenicity test proved the role of the fungus in causing leaf blight on both hosts.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.4
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• pp.373-381
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• 1999

Six soybean cultivars having different SDS susceptibility were planted with sorghum seedinoculum infested with F. solani isolate 171 in the greenhouse. First leaf symptoms appeared on unifoliar leaves at 9 days after inoculation and all cultivars showed the typical leaf symptoms at 13 days after inoculation, when trifoliar leaves emerged. Leaf symptoms development in susceptible cultivars was faster than in resistant cultivars. Leaf symptom severities during the period of 25 to 29 days after inoculation showed a significant difference between cultivars which had SDS resistance and sus ceptibility. In this period, area under the diseaseprogress curve (AUDPC) of Hartz 6686 was the highest and that of PI 520733 was the lowest. SDS caused serious damage to the growth of soybean in all cultivars. Average reductions of growth rate of root fresh weight and dry weight were greater than those of plant tops. Duyu-kong showed less severe leaf symptoms than that of SDS suscetible cultivars; however, average growth rate of plants top and roots of this cultivar was less but not significantly different than those of SDS susceptible cultivars. In all cultivars, as severity of leaf symptoms increased, plant top weight decreased. Root rot symptoms were observed in all cultivars before leaf symptoms appeared. Average proportions of tap root reddish-brown discoloration of all cultivars was up to 75 % at 15 days after inoculati on; however there was no significant differenc between cultivars at each rating date. Appearances of leaf symptoms on leaves varied in each cultivar. SDS resistant cultivars had a significantly higher level of crinkling than susceptible cultivars and SDS susceptible cultivars had a significantly higher level of necrosis than resistant cultivars. Further study will be needed to identify the relationships between the physiological growth rate and SDS severities in soybeans.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.154-159
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• 2000

This study was carried out to elucidate the symptom of leaf injury to ozone and to determine varietal difference to ozone injury in rice and soybean plant. Ozone was produced by electrostatic discharge in oxygen and was monitored by UV absorption ozone analyzer. The rice leaves were spotted red and rolling leaf edge, discolored to reddish brown or yellowish white in response to ozone, and the leaves that were severely stressed were withered from the tip of leaf. The soybean ones were also discolored to lemon yellow, yellow or dark brown. The leaf injury in both rice and soybean was clearly appeared at the reverse side of leaf and in lower leaves. Milyang 23 and Nonganbyeo among rice cultivars tested were resistant to ozone, but Chucheongbyeo was resistant to it. The ratio of leaf injury was increased and chlorophyll content was decreased as the extension of ozone exposure from 2 to 8 hours in rice. Keunolkong and Danyeopkong among soybean cultivars tested showed resistant reaction to ozone, but Kwangankong and Muhankong were susceptible to it. It was observed that the soybean plants grown for 45 days after seeding were severely damaged by ozone than those of other growth stages.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.181-191
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• 1994

Occurrence of diseases in economic resource plants in Korea is poorly known. This paper reports short descriptions on symptom, occurrence condition, pathogen, and some phytopathological notes for each 10 fungal plant diseases new to Korea; leaf spot of Rosa multiflora with Seimatosporium discosioides causing leaf spot and defoliation, leaf blight of Equisetum arvense with Titaeospora equiseti causing leaf spot to leaf blight, leaf blight of Setaria viridis with Phyrenochaeta setariae causing leaf spot of Aster tataricus with Septoria astericola causing leaf spot and black spot, powdery mildew of Clematis fusca var. coreana with Erysiphe ranunculi causing powdery mildew and dwarfing, powder mildew of Ligularia stenocephala with Erysiphe galeopsidis causing powdery mildew and dwarfing, powdery mildew of Phlox subulata with Erysiphe cichoracearum causing powdery mildew and defoliation tar spot of Lonicera japonica with Rhytisma lonicericola causing tar spot and dwarfing, white rust of Pharbitis nil with Albugo ipomoeae-pandulatae causing white rust and deformation, and white rust of Achyranthes japonica with Albugo achyranthis causing white rust and defoliation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.925-927
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• 2012

On-site diagnosis applied to soil having a symptom of yellowing and whitening in cucumber leaf and stem. Soil pH determined 4.2 by methods of on-site analysis and 4.5 by soil test analysis. High aluminum in soil solution extracted with water saturation was detected. Leaf and stem tissue were abundant in Al content but not in Ca. Also, N content of leaf and stem was low compared to normal N ranges. This symptom of cucumber assumed to be from the Al and nitrous acid gas toxicity by low soil pH and Eh. Conclusionally, symptom in leaf and stem of cucumber was alleviated and cucumber normally recovered during cultivation period by applying calcium hydroxide solution to correct soil pH up to 6.5. These results showed that low soil pH resulted in aluminum toxicity and N deficiency to plant growth in on-site farming.

• Journal of the Korean Society of Tobacco Science
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• v.18 no.2
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• pp.107-112
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• 1996

The occurrence and chemical properties of grey tobacco leaves (Type III) found in 1995 crop of flue-cured tobacco cultivated in paddy field were investigated to compare with those of normal leaves. Cured leaves of NC82 were separated by visual characters into 3 classes of slight, fair and severe symptoms of grey leaf by the percentage of grey parts to whole leaf area. Number of samples classified with discoloring portion was the order of greyish brown > reddish brown > greyish yellow, respectively. Grey leaves of this type were mostly found among the leaves harvested from upper stalk position, and it was estimated that growth rate of upper leaves also influenced on the occurrence of grey leaves. Grey leaves showed remarkably lower b* and L* values than those of normal leaves, while a* value was mostly higher in grey leaves. These tendencies in chromatic aberration showed more remarkable difference in the degree of grey symptoms. Chemical analyses of grey leaf samples indicated that they contained less total nitrogen and nicotine, and more total sugar and starch than those of normal leaves. In chemical traits, these tendencies were accordance with the degree of grey symptoms, and within the same leaf, grey parts were decreased in total nitrogen and ether extract content compared with those of normal parts, but there was no difference in nicotine and Cl contents. Key words : grey leaf tobacco (type III), grey symptom, color, chemical properties.

• Journal of Sericultural and Entomological Science
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• v.37 no.1
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• pp.86-91
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• 1995

Isolation and pathogenicity of Fusarium spp. from mulberry shoot rot and severity of diseases which were known as bacterial blight were examined on four mulberry varieties in Suwon, Kongju and Chuncheon, A symptom of mulberry shoot rot was initiated long brown spot on young leaves and shoots. It was developed into dark brown spot and produced white mycelia and spores on the diseased symptoms. A symptom of bacterial blight showed leaf rolling and water soaking spot and produced bacterial ooze on leaf and shoot However later stage of upper two types of symptom was hardly distinguished. Severities of shoot rot and bacterial blight were 7.5% and 4.4% in Suwon, respectively. Isolation of Fusarium spp. on shoot rot symptoms was highter than that on bacterial blight symptoms, but isolation of Pseudomonas spp. was higher on bacterial blight symptoms. Trends of pathogenicity of Fusarium spp. and Pseudomonas spp. were similar to inoculation works, and isolations of pathogenic Fusarium spp. from center of symptom was higher than that from 30cm of symptom of all samples in three cultivation areas. Disease severities of shoot rot on variety of Kaeryangppong were 13.9%, 15.9% and 17.2% in Suwon, Kongju and Chuncheon, respectively. However variety of Cheongolppong was highly resistant to shoot rot disease in three cultivation areas.