• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.409-414
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• 2009

In 1970's Black locust(Robinia pseudoacacia) had been widely planted Korea as an important forest greening species for erosion control afforestation. Since 2000, however, the tree's leaf-yellowing symptom has often been observed at a limited region and then spreaded out over the country in 2006. This study was conducted to study soil physiochemical properties of black locust stands with and without the leaf-yellowing symptom in Osan, Gyeonggi province. Most of soils in sampling sites were mostly slightly eroded, dry, and moderately dry. Available soil depth(16cm) and total soil depth(26cm) in leaf-yellowing (LY) site were significantly lower than in non leaf-yellowing (Non-LY) site's soil depths which were 30cm and 56cm, respectively. And solid phase proportion and bulk density in soils were lower in LY site than in non-LY site soils, while soil liquid phase proportion was also low. It could reflect that LY site soils might have a lower air and moisture movement in the rhizosphere of black locust stand compared with non-LY site soils. Soil acidity in both sites was very strong acid, soil pH (4.42) of LY site was slightly lower than non-LY site's (pH 4.54). Content of available phosphorous, exchangeable $Ca^{2+}$ and $Mg^{2+}$ and percent base saturation were less than LY site. These results indicated that soil physiochemical condition in LY site, more deteriorated than non-LY site, should adversely affect the retention and supply capacity of soil nutrients and moisture. Therefore the black locust may be more sensitive to other environmental stresses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.459-480
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• 1991

Physilogical disorders of P. ginseng occurred in farmer's field were reviewed in relation to symptom. In root, red skin, rough skin, rust, root rot complex, round root, fine root stripe, freezing injury, cracking, sleeping and uneven emergence were frequently appeared. In leaf and stem, yellowing, early defoliation, leaf bum, Papery leaf, white freezing injury, wind injury, stem cracking were the main troubles. Red skin of root and leaf yellowing gave the greatest negative impact on ginseng production. Some cases of damage by pesticides, excess boron and industrial pollutants were reported. Physiological disorders related to quality factors, such as inside cavity, inside white sponge-like ect. after processing were discussed.

• Journal of Forest and Environmental Science
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• v.39 no.1
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• pp.49-54
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• 2023

For unknown reasons, a few trees in a private chestnut orchard in Icheon si, Gyunggi-do suffered leaf chlorosis and growth decline. Based on symptoms, phytoplasma was a probable cause. Leaf samples were collected from two symptomatic and non-symptomatic trees in the orchard for phytoplasma detection. An amplicon of about 1.2 bp size was obtained from both symptomatic trees by PCR with the universal 16S rDNA primers. Sequences of these amplicons were found to have 99% nucleotide sequence identity to the corresponding genomic region of 16SrIII (X-disease group). More than 100 phytoplasma isolates, such as Candidatus phytoplasma pruni, Milkweed yellows phytoplasma, Goldenrod yellows phytoplasma, Tsuwabuki witches'-broom phytoplasma, Candidatus Phytoplasma trifolii, etc. were involved in the list. Phylogenetic analysis revealed that the sequence obtained in this study closely clustered with Candidatus phytoplasma groups. While one of the amplicons shared 91% identity with the Candidatus phytoplasma castaneae, the other shared only 47%. It needs further analysis and investigation to determine the exact taxonomy. Meanwhile, based on the analysis of the sequences, chlorosis, and small leaves were associated with phytoplasma.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.975-977
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• 2010

Ammonium nitrogen is volatilized as ammonia at high pH soil. This study was conducted to observe an injury cause of egg plant grown in a high pH rockwool amended with ammonium phosphate. The etiolation symptom (yellowing) was appeared on veins of a leaf but not in healthy root when nutrient solution containing ammonium phosphate in addition to essential elements was applied in a top soil of which pH was 7.8. However, the same symptom did not appeared in the egg plant from the top soil in which the nutrition solution containing potassium phosphate instead of ammonium phosphate was applied. pHs were similar between these two different solutions. This revealed that the injury was caused by ammonia gas.

• Weed & Turfgrass Science
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• v.5 no.1
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• pp.23-28
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• 2016

Zoysiagrass possessing the leaf yellowing with excessive tillers was first found in a golf course in Gyunggi province at last three to four years ago and since then have rapidly spread many golf courses in Korea. The symptom is very similar to that of yellow tuft or downy mildew, which is caused by Sclerophthora macrospora, on cool-season turfgrasses including Kentucky bluegrass and ryegrass. Microscopic study was firstly carried out to look over the presence of the pathogen in the infected leaf and stem tissues. Oospores and sporangia, reported as typical indicators of downy mildew, were obviously observed from the infected leaves. Using a set of primers based on the 18S ribosomal DNA from S. macrospora, the specific DNA fragment corresponding the gene was amplified. This study reveals that S. macrospora might be involved in spread of leaf yellowing of zoysiagrass with excessive tillers.

• The Plant Pathology Journal
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• v.23 no.1
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• pp.34-36
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• 2007

Introduction of vegetatively propagated Petunia hybrids since 1992 led to increasing virus infections of propagation material. Petunia hybrid 'Surfinia' cultivated for pot-plant showed yellowing symptom along with stunt. Flowers were smaller in size and showed color-break symptom. Tobacco mosaic virus(TMV-pet) was isolated from the diseased petunia. Healthy petunia plants inoculated with TMV-pet induced mottle on leaves and color-break on flowers, and plants were stunted. Nucleotide sequences of coat protein gene amplified from RNA prepared from Nicotiana tabacum cv. Samsun infected with TMV-pet were determined(GenBank accession no. DQ981481). It showed 99.0% nucleotide sequence homology with TMV-potato3-2(GenBank accession no. AF318215) isolated from potato showing yellow mosaic and stunt symptom, and with a TMV Korean strain(GenBank accession no. X68110). This is the first reported observation of TMV from vegetatively propagated petunia in Korea.

• Research in Plant Disease
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• v.12 no.3
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• pp.221-225
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• 2006

Cucumber mosaic virus(CMV) and Broad bean wilt virus 2(BBWV2) were isolated from Gentiana scabra plants showing typical mosaic and yellowing symptoms. When the inoculum of mosaic symptom propagated in Nicotiana benthamiana was inoculated to primary leaves of Vigna sinensis, the local lesions of different types was developed. Type one produced a small necrotic spot(SNS) of pinpoint type, while the other one showed a large necrotic spot(LNS) of halo type. LNS on primary leaves of V. sinensis was also induced by inoculum from yellowing symptom on G scabra. Single lesion from SNS induced a typical mosaic symptom on N. Benthamiana. On the other hand, LNS produced a chlorotic ring symptom on inoculated leaves and mosaic plus necrotic ringspot on upper leaves of N. benthamiana. An isolate of CMV from SNS and BBWV2 from LNS were detected by using dsRNA analysis, RT-PCR and agar gel double-diffusion test. Thus, our results should provide a tool of a simple method for discrimination from mixed infected plants by CMV and BBWV2.

• Research in Plant Disease
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• v.9 no.1
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• pp.36-38
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• 2003

Stem blight of brunfelsia (Brunfelsia calycina) caused by Fusarium oxysporum was found in greenhouse around Sungnam area, Kyunggi province, Korea in September 2001. The initial infection appeared as a slight wilting of the foliage, turned yellow from the lower leaves. The yellowing leaves were falled, resulting in blight of stem and eventual death of the entire plant. The vascular tissue of a diseased plants became dark brown and browning of the vascular system was a characteristic of the disease and the pith remained healthy, Isolates obtained from the lesions of the diseased plant were identified as F. oxysporum, based on the morphological characteristics of conidia. Symptom by artificial inoculation was same to the symptom of naturally infected plants. This is the first report demonstrating the stem blight on a brunfelsia caused by F. oxysporum in Korea, and we proposed to name this disease "stem blight of brunfelsia".

• Research in Plant Disease
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• v.9 no.1
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• pp.18-20
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• 2003

Canker farmed on a pomegranate tree(Punica granatum) with yellowing leaves and death of some twigs was founded at a garden of Gyungbuk Agricultural Technology Administration. Botryosphaeria dothidea was isolated from the canker and pathogenisity of the isolate was confirmed by artificial inoculation to the pome-granate twig, which showed the same symptom with naturally infected twig. This is the first report of a natural infection of pomegranate tree by Botryosphaeria dothidea in Korea.

• 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.