• Research in Plant Disease
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• v.12 no.2
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• pp.129-133
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• 2006

A bacterial disease of small red bean (Phaseolus angularis) was observed on field-grown plants in Suwon in year 2003. Leaf symptoms initially appeared as water-soaked spots that gradually enlarged, became flaccid and necrotic and were often bordered by a small zone of lemon yellow tissue. In the case of severe infection, dead leaves were defoliated. Pod symptoms consisted of the lesions that were generally circular, slightly sunken and dark reddish brown. Isolation made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow-pigmented bacterium typical of a xanthomonad. Three bacterial strains were purified and used for further tests. Pathogenicity of strains was confirmed on 3-week-old small red bean plants sprayed with bacterial suspensions containing $10^8 cfu/ml$ of phosphate buffered saline. The representative Xanthomonas strains isolated from small red bean were compared with X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans type strains for fatty acid profiles, biochemical tests and metabolic fingerprints using Biolog GN2 microplate, showing that all outcomes were indistinguishable between our isolates and reference strains. Two of three strains produced a melanin-like brown pigment extracellularly on King's medium B agar. These results suggest that this new small red bean disease observed in Suwon is bacterial fuscous blight caused by X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans.

• Research in Plant Disease
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• v.25 no.3
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• pp.136-142
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• 2019

Drought stress is considered as one of major abiotic stresses; it leads to reduce plant growth and crop productivity. In this study, we selected bacterial strains for alleviating drought stress in chili pepper plants. As drought-tolerant bacteria, 28 among 447 strains were pre-selected by in vitro assays including growth in drought condition with polyethylene glycol and plant growth-promoting traits including production of 1-aminocyclopropane-1-carboxylate deaminase, indole-3-acetic acid and exopolysaccharide. Sequentially, 7 among pre-selected 28 strains were screened based on relative water content (RWC); GLC02 and KJ40, among seven strains were finally selected by RWC and malondialdehyde (MDA) in planta trials under an artificial drought condition by polyethylene glycol solution. Two strains GLC02 and KJ40 reduced drought stress in a natural drought condition as well as an artificial condition. Strains GLC02 or KJ40 increased shoot fresh weight, chlorophyll and stomatal conductance while they decreased MDA in chili pepper plants under a natural drought condition. However, two strains did not show biocontrol activity against diseases caused by Phytophthora capsici and Xanthomonas campestris pv. vesicatoria in chili pepper plants. Taken together, strains GLC02 or KJ40 can be used as bio-fertilizer for alleviation of drought stress in chili pepper plants.

• The Korean Journal of Pesticide Science
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• v.12 no.4
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• pp.335-341
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• 2008

In this study, hexaconazole 5% SC, an ergosterol biosynthesis inhibitor, was tested on groundnut with its recommended ($500\;mL\;ha^{-1}$) and higher ($2,000\;mL\;ha^{-1}$) concentrations under greenhouse conditions in India. Its influence on biochemical constituents of groundnut plants was assessed apart from its disease management potential against late leaf spot caused by Phaeoisariopsis personata (Berk and Curt). Likewise, leaf samples were collected from hexaconazole 5% SC-sprayed plants at different time intervals. Thereafter, their analyses showed considerable differences in the plant constituents, such as chlorophyll, soluble protein, and total phenol contents and the activity of nitrate reductase enzyme. The induction activity of defense-related enzyme, peroxidase, was also analyzed. However, no difference was observed in the isozymic pattern. Moreover, the ground kernels collected from treated plants also showed no difference in the estimated carbohydrate and other constituents.

• The Korean Journal of Mycology
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• v.30 no.2
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• pp.173-175
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• 2002

Sooty leaf blight was found on Dendrobium sp. in several farmers' fields located in Namji-eup, Changnyeong-gun, Gyeongnam province, Korea in 2001. Symptoms of the disease appeared on leaves. Sooty leaf spots were started with amphigenous, subeircular to irregular spots, with light grayish brown to black color with definite margin lines on the upper surface of leaves. Infected leaves became defoliated and whole plants eventually were died. The infection rates of the disease in the surveyed area reached up to 64.8%, in the early September. Conidiophores of the causal fungus were dark grayish brown in color, densely fasciculate, straight, curved to sinuous, branched, $5{\sim}10$ septate and $63{\sim}164{\times}3.2{\sim}4.9{\mu}m$ in size. Conidia were pale to olivaceous in color, obclavatecylindric, straight to slightly curved in shape, $1{\sim}5$ septate and $46{\sim}98{\times}3.2{\sim}3.9{\mu}m$ in size. The optimum temperature for mycelial growth of the fungus was $25^{\circ}C$. The fungus was identified as Pseudocercospora dendrobii on the basis of its mycological characteristics. This is the first report on sooty leaf light of Dendrobium sp. caused by Pseudocercospora dendrobii in Korea.

• Journal of Life Science
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• v.14 no.4
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• pp.689-695
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• 2004

This study was investigate the occurrence of bottom rot caused by Rhizoctonia solani at the crisphead lettuce fields in Uiryeong-gun, Gyeongsangnam-do from November to December in 2003. Incidence of bottom rot on crisphead lettuce was up to 5.3% at the six plastic houses. A total of 30 isolates of R. solani were obtained from diseased leaves of plants and were tested by artificial inoculation to the host. Among them, PY-1 isolate was selected showing highly virulent on the whole plant and was identified as R. solani AG1 (IB) based on the anastomosis test, morphological and cultural characteristics. Symptoms of bottom rot by PY-1 isolate produced small dark brown, depressed and elliptical spots on the lower part of leaves in the early stage as same as at the fields, were enlarged onto the upper part of leaves later, and the infected plant wilted and ultimately died in the end. For the pathogenicity test, triturated mycelia-inoculum (A$_{550}$=1.0) of PY-1 isolate was selected the most effective inoculum showing disease incidence of 51.1% for the mycelial inoculation at pot assay. Otherwise, WSRP media-inoculum (wheat brane ： sawdust ： rice brane ： PDB media=30 g ： 10 g ： 10 g ： 100 ml, w/w/w/v) of PY-1 isolate was effectual inoculum showing disease incidence of 61.6% for soil inoculation at the plastic house. Also, in selection of density and amount of inoculum, most suitable density of triturated mycelia-inoculum and amount of WSRP media- inoculum were determined as $A_{550}$=1.0 and 40 ml, respectively. This is the first report on the pathogenicity test using by WSRP media-inoculum of R. solani PY-1 isolate for the bottom rot of crisphead lettuce.

• Korean Journal of Organic Agriculture
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• v.18 no.1
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• pp.83-92
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• 2010

Organic farming is a type of agricultural practices based on naturally occurring processes excluding or strictly limiting the use of synthetic fertilizers, pesticides, and other chemicals. This study was conducted to investigate the influences of agro-based materials, effective microorganisms (EM), liquid silicate (LS), and organic liquid fertilizer (OLF) for water dropwort (Oenanthe stolonifera DC.) cultivation. Soil pH, soil organic matter, and plant available phosphorous decreased with LS application. Exchangeable Ca and Mg decreased with EM application, and electrical conductivity and exchangeable Ca and K decreased with OLF application. Most of essential nutrient contents in water dropwort were reduced with the treatments of LS, EM, and OLF as compared with those in control plot, except nitrogen and phosphorus. However, diseases and insect pests were almost not observed in the water dropwort in the agro-based material application plots, except cluster caterpillar (Spodoptera litura). Productivity of water dropwort tended to be reduced: its higher productivity in the OLF and EM+LS plots and lower in the LS and control plots.

• Research in Plant Disease
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• v.7 no.3
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• pp.134-139
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• 2001

Effects of tomato-juice and KH$_2$PO$_4$ as exogenous nutrients on the infection of Botrytis cinerea LVF12 and pathogenicity to tomato were investigated. B. cinerea LVF12, which was previously reported as a casual agent of the gray mold rot of perilla, was used for pathogenesis on tomato leaves. No infection was induced, and no lesion developed on tomato leaves by the conidial suspension of LVF12 when the inoculum was prepared in sterilized water. However, when the conidial suspensions of LVF12 added with various concentrations and conditions of tomato-juice were inoculated on whole tomato plants, the disease was induced readily, Among them, 20% tomato juice with 0.1M KH$_2$PO$_4$ appeared to be the most suitable nutrient to promote high disease incidence on tomato. For the pathogenicity test according to the growing stage of tomato, the mature leaves were more susceptible than seedlings. Symptoms on the infected plants were initial small gray spots at the inoculated area. Later the whole leaves, petioles and stems became gray and eventually fell off, Under high humidity conditions, the diseased leaves and stems were covered with gray hyphae and conidia. All symptoms of infected plants were identical to those in the field conditions.

• Journal of Korean Society of Forest Science
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• v.78 no.2
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• pp.103-118
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• 1989

The occurrence of witches' broom in Ligustrum ovalifolium was first noticed in Korea by author in 1984. The present study was carried out with particular emphasis on the symptomatology, etiology, transmission of the disease and antibiotic treatments. The infected tissue was observed by the fluorescence and electron microscopy and its biochemical characteristics were compared with healthy one by electrophoresis. The results are summarized as follows : 1. symptoms of the infected trees were characterized by the dwarfing of the organs, yellowing and brooming of the foliage. 2. The observation by the trans electron microscopy on the witches' broom of L. ovalifolium revealed the occurrence of numerous mycoplasma-like organisms(MLOs) in the phloem tissue cells of the midribs of infected leaves. 3. The MLOs were surrounded by a single unit membrane, and they appeared to be multiplied by binary fission. 4. The presence of crystals unidentified in the phloem parenchyma cells was noticed by electron rnicroscopy, 5. The disease was able to be transmitted by budding, crown, and greenwood graftings to L. ovalifolium, L. obtusifolium, L, japonicum and also transmitted, even when the stocks and scions were not completely grafted. 6. Insect transmission on L. ovalifolium and L, obtzrsifolium was carried by Hishimonus sellatus. 7. The infected roots dipped in the 1,000 ppm of teracyclin solution was only temporarily effective in controlling the disease. 8. Infected plant with MLOs showed specific fluorescent reactions in phloems with DAPI stain. 9. The protein and peroxidase separated by electrophoresis showed strikingly distinctive difference between the healthy and diseased leaves.

• Journal of Mushroom
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• v.20 no.3
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• pp.113-118
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• 2022

This study was conducted to diversify the cultivation of mushroom items and develop a competitive variety of Hypsizigus marmoreus. We focused on developing Hypsizigus marmoreus with lower bitterness, likable shape, and high yield. We have collected and tested characteristics of genetic resources from domestic and abroad since 2019. Breeding (2019), characterization (2020), productivity test (2021), and farm demonstration test (2021) have been sequentially conducted. We bred the new variety 'Yunseul' with unique traits. The optimal temperature for mycelial and fruit body growth were 22-25℃ and 15-18℃, respectively. It was similar to the control variety (Mangadak-2Ho) in the pileus form (hemispherical shape) and the cultivation period. However, it was thinner and longer than the control variety with the pileus diameter, thickness, stipe diameter, and length being 19.9 mm, 7.0 mm, 9.4 mm, and 86.3 mm, respectively. The effective number of fruit bodies was 47.8 in bottle cultivation, which was more than that of the control variety. The yield was 197.4 g/bottle (1,100 cc), which was 30% higher than the yield of the control variety, 151.9 g/bottle (1,100 cc). The parent and control varieties were also incubated alongside the new variety. The somatic incompatibility line was distinct. The band pattern in the mycelial DNA PCR reaction was different from that of the parent and control varieties, confirming the hybrid species.

• Journal of Practical Agriculture & Fisheries Research
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• v.10 no.1
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• pp.43-58
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• 2008

This research was conducted to determine the alternative tool of chemical spray for rice cultivation using the unmanned helicopter(Yamaha, R-Max Type 2G-remote controlled system) at farmer's field in Korea. The unmanned helicopter tested was introduced form Japan. In Korea the application of chemicals by machine sprayer for pest management in rice cultivation has been ordinarily used at the farmer's level. However, it involved a relatively high cost and laborious for the small scale of cultivation per farm household. Farm population has been highly decreased to 7.5% in 2002 and the population is expected to rapidly reduce by 3.5% in 2012. In Japan, pest control depending on unmanned helicopter has been increased by leaps and bounds. This was due in part to the materialization of the low-cost production technology under agricultural policy and demand environmentally friendly farm products. The practicability of the unmanned helicopter in terms of super efficiency and effectiveness has been proven, and the farmers have understood that the unmanned helicopter is indispensable in the future farming system that they visualized. Also, the unmanned helicopter has been applied to rice, wheat, soybean, vegetables, fruit trees, pine trees for spraying chemicals and/or fertilizers in Japan Effect of disease control by unmanned helicopter was partially approved against rice blast and sheath blight. However, the result was not satisfactory due to the weather conditions and cultural practices. The spray density was also determined in this experiment at 0, 15, 30, and 60cm height from the paddy soil surface and there was 968 spots at 0cm, 1,560 spots at 15cm, 1,923 spots at 30cm, and 2,999 spots at 60cm height. However, no significant difference was found among the treatments. At the same time, there was no phytotoxicity observed under the chemical stray using this unmanned helicopter, nor the rice plant itself was damaged by the wind during the operation.