• Research in Plant Disease
• /
• v.15 no.2
• /
• pp.88-93
• /
• 2009

In 2008, leaf rot and blight on pepper seeding ("Dokya-chungchung") occurred in a pepper farm at Hwaseong-si, Gyeonggi-do, Korea. The typical symptom is water-soaking and dark brown leaf blight at edges and tips of leaves. The fungal colonies isolated from infected tissues were pinkish at first and turned gradually to gray. Conidia were fusiform, non-septum, and $8.1-17.0{\times}2.0-3.8{\mu}m$ in size. Several specific PCR primers derived from the sequence of the internal transcribed spacer (ITS) region of the rDNA, such as CaINT, CgINT and CcINT were used for the identification of the fungal pathogen. The C. acutatum-specific primer CaINT was amplified single fragment of 496 bp that discriminated C. acutatum from the other species. The pathogenicity test was performed on seedlings and fruits of red pepper. On the basis of the morphological, molecular characteristics and pathogenicity test, we identified as Colletotrichum acutatum. This is the first report on leaf rot and blight on pepper seedling caused by C. acutatum in Korea.

• YAKHAK HOEJI
• /
• v.57 no.4
• /
• pp.241-249
• /
• 2013

We reported previously that the extracts of Yacon tuber and leaf have spermatogenic activity and testosterone level increasing effect in men. The aim of this study was to investigate the mechanism of testosterone level increasing effect of Yacon tuber and leaf extracts. In this study, we found that Yacon leaf extracts and chlorogenic acid, a constituent of Yacon extracts showed significantly inhibition effect of testosterone degradation in rat liver homogenate. We suggest that this could be a part of direct mechanism about increasing effect of testosterone level. Futhermore, we evaluated the inhibition effect of testosterone metabolism of Torilis japonica and Coix lacryma-jobi have been reported as $5{\alpha}$-reductase inhibitor. The inhibition ratio of testosterone metabolism of these were Torilis japonica>Coix lacryma-jobi>Yacon. We also evaluated the benign prostatic hyperplasia (BPH) score with the preparation composed of these natural product, Yacon pill. It showed the decreased the BPH score in men. Rats with BPH showed significantly increased dihydrotestosterone (DHT) levels in the serum; however, Yacon pill extracts treated rats showed significant reduction of DHT levels compared with the BPH group. Conclusively, Yacon pill showed the possibility as ameliorable agents of BPH symptoms.

• Horticultural Science & Technology
• /
• v.19 no.1
• /
• pp.43-47
• /
• 2001

This study was conducted to investigate the integrated control strategy against pear black leaf spot disease. Using indicator plant PS-95 we selected six virus-free trees (cv. Niitaka) from commercial orchards in the major pear production area. Disease symptom by pear black leaf spot in the shoot of pear (Niitaka) has been successfully inhibited by heat treatments for 3 weeks at temperature of $40^{\circ}C$ (day) and $32^{\circ}C$ (night) or 4 weeks at $37^{\circ}C$ and $30^{\circ}C$, respectively. However, survival rate of the shoot tips on stocks was low. Seven cultivars Niitaka, Imamura- aki, Waseaka, Nijisseiki, Wasenijisseiki, Shinsetsu and Whangkeumbae produced visible symptoms in the first year after inoculation with the virus. Other 11 selections remained symptomless. Two resistant cultivars Suwhangbae and Gamcheonbae were selected, which showed high fruit quality. It is recommended that these cultivars could be top-grafted onto the infected Niitaka trees to overcome the damage caused by the disease in the orchard.

• Research in Plant Disease
• /
• v.29 no.4
• /
• pp.433-439
• /
• 2023

Bacterial leaf blight in carrot is one of the most important diseases in the worldwide. In the past decade, its introduction into Korea is causing great concern due to the potential damage to carrot crops domestically. This bacterial disease is caused by Xanthomonas hortorum pv. carotae (Xhc). This study aimed to isolate and identify bacterial strains from the soil of carrot farms in Jeju Island. The bacterial isolates showing characteristics similar with those of Xhc were selected when cultured on artificial media. Through DNA sequencing and analysis based on NCBI data, some of the selected bacterial strains were identified as Xhc. Furthermore, the bacterial strains caused the typical symptom of bacterial leaf blight after inoculation on carrot leaves. The results of this study showed the potential establishment of Xhc in the soil of Jeju Island and it may be valuable data for establish a strategy preventing the domestic spread of carrot bacterial leaf blight in the future.

• The Plant Pathology Journal
• /
• v.40 no.2
• /
• pp.125-138
• /
• 2024

Citrus yellow vein clearing virus (CYVCV) is a member of the Alphaflexiviridae family that causes yellow vein clearing symptoms on citrus leaves. A total of 118 leaf samples from nine regions of six provinces in Korea were collected from various citrus species in 2020 and 2021. Viral diagnosis using next-generation sequencing and reverse transcription polymerase chain reaction (RT-PCR) identified four viruses: citrus tristeza virus, citrus leaf blotch virus, citrus vein enation virus, and CYVCV. A CYVCV incidence of 9.3% was observed in six host plants, including calamansi, kumquat, Persian lime, and Eureka lemon. Among the citrus infected by CYVCV, only three samples showed a single infection; the other showed a mixed infection with other viruses. Eureka lemon and Persian lime exhibited yellow vein clearing, leaf distortion, and water-soak symptom underside of the leaves, while the other hosts showed only yellowing symptoms on the leaves. The complete genome sequences were obtained from five CYVCV isolates. Comparison of the isolates reported from the different geographical regions and hosts revealed the high sequence identity (95.2% to 98.8%). Phylogenetic analysis indicated that all the five isolates from Korea were clustered into same clade but were not distinctly apart from isolates from China, Pakistan, India, and Türkiye. To develop an efficient diagnosis system for the four viruses, a simultaneous detection method was constructed using multiplex RT-PCR. Sensitivity evaluation, simplex RT-PCR, and stability testing were conducted to verify the multiplex RT-PCR system developed in this study. This information will be useful for developing effective disease management strategies for citrus growers in Korea.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.4
• /
• pp.288-295
• /
• 2013

Nitrogen dioxide ($NO_2$) gas damage on vegetable crops commonly occurs in plastic film houses where relatively large amounts of $NO_3{^-}$ are applied in acid soils. In acid soils, $HNO_2$ can be formed from the $NO_2{^-}$ accumulated during denitrification, and $NO_2$ can be evolved from the chemical self-decomposition of $HNO_2$. In this study, $NO_2$ gas production and its detrimental effects on plants were investigated in soils of various conditions to elucidate the mechanisms involved in the gas production. A silty loam soil was amended with $NO_3{^-}$ (500 mg N $kg^{-1}$) and glucose, and pH and moisture of the soil were adjusted respectively to 5.0 and 34.6% water holding capacity (WHC) with 0.01 M phosphate buffer. The soil was placed in a 0.5-L glass jar with strawberry leaf or $NO_2$ gas absorption badge in air space of the jar, and the jar was incubated at $30^{\circ}C$. After 4-5 days of incubation, dark burning was observed along the outside edge of strawberry leaf and $NO_2$ production was confirmed in the air space of jar. However, when the soil was sterilized, $NO_2$ emission was minimal and any visible damage was not found in strawberry leaf. In the soil where water or $NO_3{^-}$ content was reduced to 17.3% WHC or 250 mg N $kg^{-1}$, $NO_2$ production was greatly reduced and toxicity symptom was not found in strawberry leaf. Also in the soil where glucose was not amended, $NO_2$ production was significantly reduced. In soil with pH of 6.5, $NO_2$ was evolved to the level causing damage to strawberry leaf when the soil conditions were favorable for denitrification. However, compared to the soil of pH 5.0, the $NO_2$ production and its damage to plants were much less serious in pH 6.5. Therefore, the production of $NO_2$ damaging plants might be occurred in acid soils when the conditions are favorable for denitrification.

• Journal of Bio-Environment Control
• /
• v.13 no.1
• /
• pp.16-20
• /
• 2004

Aphis gossypii Glover(Homoptera: Aphididae) is an serious pest on various crops. This experiment was conducted to evaluate the effect of A. gossypii Glover on the growth of oriental melon and the plant recovery after removing A. gossypii. Visible damage symptom caused by A. gossypii feeding to oriental melon was leaf distortion and stunting. A. gossypii feeding for 20 days on oriental melon significantly reduced the growth of oriental melon with increasing A. gossypii density level. Plant growth was decreased by 63${\sim}$69%, 62${\sim}$88% and 49${\sim}$70% in plant height, leaf area and dry weight, respectively. During 10 day after aphids removal, the infested leaves remained stunt, however, new shoot and leaf recovered gradually. By 20 day, plant height, leaf area and dry weight substantially increased in 5 aphid per plant. Plant recovered rapidly with day and among aphid density level, 5 aphid per plant showed rapid recovery. When plant were infested with several density of aphid per plant, sugar contents of total leaves were not significantly different between aphid density level. Whereas, sugar contents of lear infested with aphid per leaf were decreased with increasing cumulative aphid-days.

• Journal of the Korean Society of Tobacco Science
• /
• v.28 no.2
• /
• pp.158-161
• /
• 2006

Main tobacco diseases were surveyed on major flue-cured leaf tobacco fields throughout South Korea in 2006. Mosaic caused by potato virus Y and bacterial wilt caused by Ralstonia solanacearum were most severe during harvest season. During last ten years, the damage by tobacco mosaic virus was reduced but the incidence of bacterial wilt increased. These changes of the disease incidences coincide with release time of the tobacco cultivar resistant to the tobacco mosaic virus but susceptible to bacterial wilt pathogen. Wild fire(Pseudomonas syringae pv. tabaci strain ungulate) occurred severely at Kangwon province, though the symptom of wild fire with yellow halo was not observed.

• Korean Journal Plant Pathology
• /
• v.3 no.3
• /
• pp.236-238
• /
• 1987

A bacterial disease of elephant foot, Hydrosome rivieri Engl., was newly found in Taejon, Korea in August 1986. The affected plants showed symptoms of soft rot on leaf blades and petioles. Bacterial isolates from affected plants found to be pathogenic to elephant foots by antificial inoculation, producing similar symptoms with those produced naturally. The baterium was also pathogenic to carrot, Chinese cabbage, radish, potato and onion, and developed symptom of soft root on them. On the basis of bacteriological characteristics and pathogenicity, tested bacterium was identified as Erwinia carotovora subsp. carotovora and this disease was proposed to name 'Bacterial soft rot of elephant foot'.

• Korean journal of applied entomology
• /
• v.20 no.1 s.46
• /
• pp.6-14
• /
• 1981

The effect of heat or chemotherapeutant treatment on the mosaic virus infected garlic(Allium sativum L.) scales and that of chemotherapeutant added to the culture medium were summarized as following. The treatment of the virus infected garlic scales at $37\~57^{\circ}C$ for 35 days to one hour in water or in air shelved no effort of inactivating the virus. Although treatment of the garlic scales at $62\~72^{\circ}C$ for 90 to five minutes reduced the mosaic symptom on the leaves of the garlic plants grown after the heat treatment, it reduced the growth vigor of the plants so greatly that complete inactivation of the virus in garlics was not feasible. The mosaic symptom on the leaves of garlic plant was reduced when the infected garlic scales were grown after 24 hours soaking in $10\~50\;ppm$ Malachite Green, 2,4-Dichlorophnoxy Acetic Acid, or in $20\~100\;ppm$ Quinhydron. These chemotherapeutants, however, inhibited the growth of garlic plant at the high concentration. Garlic scales soaked in $10\~50\;ppm$ Naphthyl Acetic Acid showed the least mosaic symptom without its complete extiction on the garlic leaves. When incorporated into the modified Murashige-Skoog's medium, $0.5\~l.5\;ppm$ Naphthyl Acetic Acid could inactivate the mosaic virus in newy developed garlic plants showing no mosaic symptom on the leaves, no inclusion bodies and intact nuclei in the leaf tissue cells.