• Weed & Turfgrass Science
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• v.3 no.4
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• pp.354-361
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• 2014

This study was conducted to investigate whether several composted liquid manures (CLMs) are useful for biological control of large patch on zoysiagrass and investigate the chemical and biological factors to suppress large patch in soil treated with CLMs. The CLMs were produced at 4 different facilities for livestock excretion treatments located in Korea. Field experiments were carried out at 5 golf courses located near each facility. CLM and Chemical fertilizer (CF: water soluble fertilizer, 20-20-20) were applied four and three times with N at $12g\;m^{-2}$ per year, respectively. There was significant increase of concentration of K, Na, and Cu of soil treated with CLM compared to CF treatment. Among experimental plots, CN and GG2 plot sites were shown significant higher effect of biological control 80% and 50% respectively against large patch disease. The number of bacteria, Actinomycetes, and fungi in soil at these sites significantly increased and fluorescein diacetate hydrolytic activity was enhanced, while the soil was treated with CLM. The results of this study demonstrated that CLM application has effect on soil to suppress large patch and reduce the use of fungicide in environment-friendly turf management.

• Journal of Applied Biological Chemistry
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• v.48 no.2
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• pp.65-74
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• 2005

Fungicidal, insecticidal, and mosquito larvicidal activities of piperidine alkaloids, pipernonaline and piperoctadecalidine, and isobutylamide alkaloids, pellitorine, guineensine, pipercide, and retrofractaminde A, derived from Piperaceae fruits were studied. Pipernonaline and piperoctadecalidine showed potent fungicidal activities against Puccinia recondita with 91 and 80% control values at 500 ppm. Against Phytophthora infestans, pipernonaline showed strong fungicidal activity with 91 and 80% control values at 1,000 and 500 ppm. $LD_{50}$ values of pipernonaline and piperoctadecalidine against Plutella xylostella were 125 and 95.5 ppm, respectively, and that of piperoctadecalidine against Tetranychus urticae was 246 ppm. Against larvae of Aedes aegypti and Culex pipiens pallens, $LD_{50}$ values of pipernonaline were 0.35 and 0.21 ppm, respectively. Highest larvicidal activities of pipercide and retrofractamide A were found against A. aegypti, A. togoi, and C. pipiens pallens. $LD_{50}$ values of pipercide and retrofractamide A were 0.10 and 0.039 ppm against A. aegypti, 0.26 and 0.01 ppm against A. togoi, and 0.004 and 0.028 ppm against C. pipiens pallens, respectively. Based upon these results and earlier findings, bioactive components derived from Piperaceae fruits may be valuable for development of useful lead product of possibly safer fungicidal, insecticidal, and mosquito larvicidal agents.

• Journal of Microbiology and Biotechnology
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• v.25 no.3
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• pp.353-357
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• 2015

A new actinomycete strain NA4 was isolated from a deep-sea sediment collected from the South China Sea and showed promising antifungal activities against soilborne fungal pathogens. It was identified as Streptomyces cavourensis by morphological, physiological, and phylogenetic analyses based on its 16S rRNA gene sequence. The main antifungal components were isolated and identified from the fermentation culture as bafilomycins B1 and C1. These compounds exhibited significant antifungal activities and a broad antifungal spectrum. The results suggest that the Streptomyces cavourensis NA4 and bafilomycins B1 and C1 could be used as potential biocontrol agents for soilborne fungal diseases of plants.

• The Plant Pathology Journal
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• v.29 no.4
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• pp.418-426
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• 2013

Pseudomonas isolates from different crop plants were screened for in vitro growth inhibition of Phytophthora capsici and production of biosurfactant. Two in vivo experiments were performed to determine the efficacy of selected Pseudomonas strains against Phytophthora blight of pepper by comparing two fungicide treatments [acibenzolar-S-methyl (ASM) and ASM + mefenoxam]. Bacterial isolates were applied by soil drenching ($1{\times}10^9$ cells/ml), ASM ($0.1{\mu}g$ a.i./ml) and ASM + mefenoxam (0.2 mg product/ml) were applied by foliar spraying, and P. capsici inoculum was incorporated into the pot soil three days after treatments. In the first experiment, four Pseudomonas strains resulted in significant reduction from 48.4 to 61.3% in Phytophthora blight severity. In the second experiment, bacterial treatments combining with olive oil (5 mL per plant) significantly enhanced biological control activity, resulting in a reduction of disease level ranging from 56.8 to 81.1%. ASM + mefenoxam was the most effective treatment while ASM alone was less effective in both bioassays. These results indicate that our Pseudomonas fluorescens strains (6L10, 6ba6 and 3ss9) that have biosurfactant-producing abilities are effective against P. capsici on pepper, and enhanced disease suppression could be achieved when they were used in combination with olive oil.

• The Plant Pathology Journal
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• v.31 no.2
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• pp.176-180
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• 2015

Postharvest diseases cause losses in a wide variety of crops around the world. Irradiation, a useful nonchemical approach, has been used as an alternative treatment for fungicide to control plant fungal pathogens. For a preliminary study, ionizing radiations (gamma, X-ray, or e-beam irradiation) were evaluated for their antifungal activity against Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer through mycelial growth, spore germination, and morphological analysis under various conditions. Different fungi exhibited different radiosensitivity. The inhibition of fungal growth showed in a dose-dependent manner. Three fungal pathogens have greater sensitivity to the e-beam treatment compared to gamma or X-ray irradiations. The inactivation of individual fungal-viability to different irradiations can be considered between 3-4 kGy for B. cinerea and 1-2 kGy for P. expansum and R. stolonifer based on the radiosensitive and radio-resistant species, respectively. These preliminary data will provide critical information to control postharvest diseases through radiation.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.95.2-96
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• 2003

In order to develop a new microbial fungicide for the control of vegetable diseases using endophytic bacteria, a total of 260 bacterial strains were isolated from fresh tissues of 5 plant species. After they were cultured in broth media, their antifungal activities were screened by in vivo bioassays against Botrytis cinerea(tomato gray mold), Pythium ultimum(cucumber damping-off), Phytopkhora infestans(tomato late blight), Colletotrichum orbiculare(cucumber anthracnose), and Blumeria graminis f. sp. hordei(barley powdery mildew). As the results of screening, 38 bacterial strains showed potent antifungal activities against at least one of 5 plant pathogens. A bacterial strain EB072 displayed potent disease control activities against 3 plant diseases. Among the bacterial strains with a potent antifungal activity against cucunlber anthracnose, three bacterial strains, EB054, EB151 and EB215, also displayed a potent in vitro antifungal activity against C. acutatum, a fungal agent causing pepper anthracnose. A bacterial strain EB215 obtained from roots of cucumber was identified as Burkholderia cepacia based on its physiological and biochemical characteristics and 165 rRNA gene sequence. An antifungal substance was isolated from the liquid cultures of B. cepacia EB215 strain by ethyl acetate partitioning, repeated silica gel column chromatography, and invitro bioassay, Its structural determination is in progress by various instrumental analyses.

• The Plant Pathology Journal
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• v.27 no.4
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• pp.342-348
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• 2011

Bacillus subtilis EBS05, an endophytic bacteria strain isolated from a medicinal plant Cinnamomum camphor, can produce antagonistic compounds that effectively inhibit plant pathogenic fungi. The greenhouse experiments showed that wheat sharp eyespot disease (WSED) was reduced by 91.2%, 88.2% and 43.0% after the treatment with fermentation broth, bacteria-free filter and a fungicide fludioxonil, respectively. The culture broth of strain EBS05 can more effectively control WSED than can fludioxonil. The fermentation broth and bacteria-free filter ability to suppress WSED was not significantly different, suggesting that an active secreted substance played a major role in controlling WSED. Separation and purification of the active compounds was carried out by serial processes, including hydrochloric acid (pH 2.0) treatment, methanol extraction and Sephadex LH-20 column chromatography, silica gel column chromatography and reverse-phase high-pressure liquid chromatography (HPLC), respectively. The purified compounds, one of active peaks in the HPLC spectrum, were obtained from the collection. Analysis of the chemical structures by time-of-flight mass spectrometry (TOF-MS) and electrospray ionization mass spectrometry/mass spectrometry (ESI-MS/MS) showed that the active substances produced by the endophytic bacteria EBS05 are mixture of the ${\beta}$-hydroxy-C12~C15-$Leu^7$ surfactin A isomers with 1035.65 Da, 1021.64 Da, 1007.63 Da and 993.65 Da molecular weights, respectively.

• Analytical Science and Technology
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• v.12 no.1
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• pp.47-52
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• 1999

Antifungal substances were isolated and identified from garlic and taxus extracts to develop safe and broad fungicide. The inhibitory effect of seedborn disease of sesame, pepper, radish, chinese cabbage by formulation of antifungal substances was investigated. The antifungal substance isolated through column chromatography from garlic and taxus extracts was confirmed by GC-MS as allicin($C_6H_{10}OS_2$) and taxol($C_{47}H_{51}NO_{14}$) and the quantified content from each extracts by HPLC analysis was 0.62%, 0.29%, respectively. The formulation composed of garlic and taxus extracts controlled effectively the seedborn fungi tested in this study at 10X dilution, but at 100X dilution the inhibitory effect decreased. Phytotoxicity of these formulations did not recognized.

• Research in Plant Disease
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• v.20 no.2
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• pp.101-106
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• 2014

Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is one of the most important diseases on citrus. Although Satsuma mandarin cultivating mostly in Korea is moderately resistance to canker, occurrence of the disease were more frequently reported since last decade. Like other diseases in citrus, citrus canker was mainly protected by chemical fungicide in the field. Due to the side effect of the chemicals, alternative method of disease control is recently required. In this study four rhizobacterial strains TRH423-3, MRL408-3, THJ609-3 and TRH415-2 are selected by testing its antifungal activity against Xcc. Pre-inoculation with the selected rhizobacterial strains caused disease suppression on the citrus leaves after inoculation with the citrus canker pathogen. Similarly, in the field test symptoms of citrus canker were less developed in the citrus trees applied several times with the selected rhizobacterial strains compared with those of untreated trees. Therefore, it is suggested that the selected rhizobacterial strains may be valuable as an alternative method in the environment-friendly citrus farm.

• Journal of Microbiology and Biotechnology
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• v.16 no.2
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• pp.280-285
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• 2006

Methanol extract of the rhizomes of turmeric, Curcuma longa L., effectively controlled the development of red pepper anthracnose caused by Colletotrichum coccodes. In addition three antifungal substances were identified from the methanol extract of C. longa rhizomes as curcumin, demethoxycurcumin, and bisdemethoxycurcumin using mass and $^{1}H-NMR$ spectral analyses. The curcuminoids in a range $0.4-100\;{\mu}g/ml$ effectively inhibited the mycelial growth of three red pepper anthracnose pathogens, C. coccodes, C. gloeosporioides, and C. acutatum. The three curcuminoids inhibited mycelial growth of C. coccodes and C. gloeosporioides to an extent similar to the synthetic fungicide dithianon did, but the synthetic agent was a little more effective against C. acutatum. The curcuminoids also effectively inhibited spore germination of C. coccodes, and bisdemethoxycurcumin was the most active. Among the three curcuminoids, only demethoxycurcumin was effective in a greenhouse test in suppressing red pepper anthracnose caused by C. coccodes.