• Microbiology and Biotechnology Letters
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• v.27 no.6
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• pp.427-432
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• 1999

For the development of a multifunctional biocontrol agent, the siderophore-producing strain GL7 was isolated from a rhizosphere on chrome azurol S agar. The GL7 was identified as a strain of Pseudomonas fluorescents on the basis of their reactions to standard physicochemcial tests from Bergey's manual, API diagnostic test, and fatty acid analysis. P. fluorescents GL7 considerably inhibited spore germination and hyphal growth of phytopathogenic fungus Funsarium solani in a dual culture. In pot trials of bean with P. fluorescens GL7, the disease incidence was significantly reduced down to 5% from 70% of incidence in the untreated control. P. fluorescens GL7 also enhanced plant growth to nearly 1.5 times than that of the untreated control, promoting elongation and development of the roots. These results suggest that the plant growth-promoting P. fluorescens GL7 can play an important role in the biological control of soil-borne plant disease in a rhizosphere.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.175-190
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• 2006

The term mycoherbicide started in 1970, but its interest heightened due to increase costs of chemical herbicides. A classical biocontrol agent is expected to become a permanent part of its new environment and do no harm to it. Contemporary biological control agent(BCA) must be produced by artificial culture and could be applied like chemical herbicides over weeds. BCA is different from the classical approach in that it released through natural spread. To date 26 species of fungi are used as classical BCA against 26 species of weeds in seven countries. There are a number of examples of pathogens attacking non-target plants. But through risk assessments which include understanding the taxonomy, biology and ecology, the target and non-target species, it will be safe to introduce of exotic pathogens to control weeds. But pathogens have not been successfully used in practice. Many mycoherbicides show potential in laboratories, but are ineffective in the field and not consistent from year to year or field to field. There is also a lack of understanding humidity, dew formation and temperature and their effects on suppression of weeds by plant pathogens. Potential pathogen must be selected as a BCA. Previous studies suggest that these pathogens must (1) produce abundant and durable inoculum in artifical culture, (2) be genetically stable and weed specific and (3) kill weeds in control. A granular preparation of mycoherbicide into sodium alginate is lighter than liquids and less bulky than organic matter. Gel forms have also been used.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.191-201
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• 2006

Dollar spot caused by Sclerotinia homeocarpa is one of major diseases in putting greens. Microorganisms antagonistic to S. homeocarpa, a pathogen of dollar spot, were primarily screened through in vitro tests, including dual culture method and triple layer agar diffusion method. In vivo tests were also conducted to select the best candidate for a biocontrol microorganism, using pot experiment. Bacillus subtilis EW42-1 and Trichoderma harziaum GBF-0208 were finally selected as biocontrol agents against dollar spot. Relative Performance Index(RPI) was used as a criterion of selecting potential biocontrol agents. B. subtilis EW42-1 and T. harzianum GBF-0208 showed resistance to several agrochemicals mainly used in a golf course. B. subtilis EW42-1 and T. harzianum GBF-0208 suppressed effectively the disease progress of dollar spot like synthetic fungicide tebuconazole in the nursery where dollar spot had seriously occurred. B. subtilis EW42-1 and T. harzianum GBF-0208 have a potential to be biocontrol agents for the control of dollar spot.

• The Korean Journal of Mycology
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• v.42 no.4
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• pp.333-340
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• 2014

The aim of this study was to isolate a potential multifunctional biocontrol agent from bacteria for control of multiple plant diseases as an alternative to fungicides. A total of 201 strains were isolated from soil undamaged by repeated cultivation in Sunchang and their ability to produce antibiotics, siderophores and extracellular enzymes such as protease, cellulase and amylase was investigated. Selected strain SCS3 produced cellulose, protease and amylase. This strain also produced siderophores and showed excellent antifungal activity against various phytopathogens. SCS3 was identified as Bacillus subtilis using 16S rRNA sequencing, and named Bacillus subtilis SCS3. Finally, physiological and biochemical characteristics of B. subtilis SCS3 were examined. From the results, B. subtilis SCS3 was found to be a useful multifunctional biocontrol agent against various phytopathogens.

• Research in Plant Disease
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• v.10 no.4
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• pp.319-323
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• 2004

This study was conducted to investigate the effect of U. atrum treatment on control of Botrytis leaf blight of lily and Botrytis gray mold of cucumber, and to evaluate the U. atrum as the biological control agent of Botrytis diseases. The antagonistic isolates CNU 9037 and CNU 9054 isolated from tomato leaves were identified as Ulocladium atrum Preuss based on morphological characteristics. This is the first record of U. atrum in Korea. In bioassays on dead leaves of tomato and cucumber, treatment of U. atrum colonized the dead leaves and suppressed sporulation of Botrytis as compared with the untreated control. The suppression of spoulation of Botrytis on dead leaf segments by U. atrum was higher when U. atrum was treated before Botrytis was treated. The effect of treatments with conidial suspension of U. atrum on leaf blight of lily and gray mold of cucumber caused by Botrytis elliptica and B. cinerea, respectively, was investigated under greenhouse conditions. Spraying U. atrum ($1{\times}10^6$ conidia per ml) at intervals of 1 week for three times resulted in a significant reduction of natural infections of lily leaves caused by B. elliptica. Protective value of U. atrum treatment was higher than that of the fungicide (procymidone) treatment. Spraying U. atrum also resulted in a significant reduction of cucumber gray mold caused by B. cinerea. Our results show that U. atrum has a potential for biological control against diseases caused by Botrytis spp, in lily and cucumber.

• Korean Journal of Weed Science
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• v.31 no.1
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• pp.103-111
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• 2011

Monochoria vaginalis var. plantaginea (Pontederiaceae) is one of the most problematic weed in the rice field in Korea. Tanysphyrus (Tanysphyroides) major was selected as a potential biological control agent for M. vaginalis. Continuous rearing of T. (T.) major was carried out from 2006 to 2007, and its morphological characteristics and ecological characteristics were investigated. This species has a single generation per year, over-wintering as an adult stage. The emergence of adults starts in later June and last until September. These observations indicate that T. (T.) major takes $22{\pm}0.7$ days to develop from egg to adulthood. Host specificity test showed that finally selected this species was suitable candidates for the biological control of M. vaginalis var. plantaginea since it showed negative host specificity against major 60 test crops.

• The Korean Journal of Mycology
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• v.44 no.3
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• pp.193-195
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• 2016

Korean ginseng (Panax ginseng) possesses various biological and pharmacological properties. Damping-off is a critical disease on ginseng seedlings, which is caused by the fungal pathogens Rhizoctonia solani and Pythium sp.. This disease is generally controlled by the application of fungicides, but also biological control is an efficient and environmentally friendly way to prevent ginseng damping-off. In a previous study, we screened soil-borne bacteria with potential applications as biological control agents for ginseng damping-off and selected the bacterial strain Streptomyces sp. A3265, producing antifungal substances guanidylfungin and methylguanidylfungin. In this study, we investigated control efficacy of Streptomyces sp. A3265 against ginseng damping-off in the field. As a result, the incidence of damping-off was significantly reduced when soaking ginseng seeds in the culture broth of Streptomyces sp. A3265.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.228-235
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• 2011

An nematophagous fungi Arthrobotrys thaumasia Nema-1 and Pseudomonas putida C-5, which degrade the collagen and gelatin, was isolated from controlled horticultural soils in Seonnam-myun, Sungju-gun, Kyungpook and Woosung-myun, Gongju-shi, Chungnam to develop biological nematode pesticide. When $5,000mL\;L^{-1}$ of A. thaumasia Nema-1 culture was treated to Meloidogyne incognita, the nematicidal activity resulted in 55% at 72 hours after treatment. While the nematicidal activity increased to 65% by treating the culture mixture of $5,000mL\;L^{-1}$ Nema-1 and P. putida C-5 after 72 hours. Furthermore, the nematicidal activity of the mixture containing cinnamon extract $50mg\;L^{-1}$, each $5,000mL\;L^{-1}$ of Nema-1 and C-5 culture was elevated to 89% at 72 hours after treatment, comparing to the result showed 17% and 57% of the nematicidal activity, respectively by the treatment of chemical nemato pesticide Fosthiazate $50mg\;L^{-1}$ and neem oil $2,000mL\;L^{-1}$. These results suggested that the mixture of microorganisms and plant extract were more effective biological nematicide than the case of only microorganism or plant extract for nematode control.

• Research in Plant Disease
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• v.24 no.1
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• pp.41-51
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• 2018

Since fire blight disease on apple and pear was produced in Korea in 2015, there were no registered chemicals to control against this disease. Instead, several antibacterial chemicals that were registered for other bacterial diseases such as soft rot and bacterial spot have been authorized by Rural Development Administration (RDA). However, these chemicals are not tested efficacy for fire blight disease except damage by those treatments on apple and pear in Korea. Thus, we evaluated efficiency using in vitro and in planta assays of antibacterial chemicals such as antibiotics and copper compounds including kasugamycin, oxytetracycline, oxolinic acid and streptomycin, and copper hydroxide, copper sulfate, oxine copper and tribasic copper sulfate, respectively. We also tested two kinds of biological agents. As expected, significant antibacterial effect was observed in vitro test of both antibiotics and copper-based chemicals. In planta test based on disease severity including ooze and water-soaked formation on immature pears, bacterial populations on blooms, and blight lesion formation in artificially inoculated shoots, kasugamycin, oxytetracycline and streptomycin have been shown the most efficiency among tested antibiotics. Four copper-based chemicals tested in this study, control effects are little bit lower than agricultural antibiotics but they seem to be available to use in terms of winter season. Biocontrol agents were also shown possibility to treat in eco-friendly farms. In addition, there are no antibiotic resistance genes in Korean isolates against antibiotics, which were selected for suppression of fire blight in this study.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.277-281
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• 2012

Bacillus sp. NAAS-1 isolated from the field of Chili pepper was tested for biocontrol activity against anthracnose pathogen of Chili pepper caused by Colletotrichum acutatum. The antifungal activity of Bacillus sp. NAAS-1 culture broth was compared with synthetic fungicide containing carbendazim (40%) and kasugamycin (3.45%). Bacillus sp. NAAS-1 showed a similar fungicidal activity against the anthracnose pathogen at the concentration of 50 ${\mu}L/mL$ in comparison to the fungicide containing carbendazim (40%) and kasugamycin (3.45%) using a cup method. Bacillus sp. NAAS-1 also exhibited its potent fungicidal activity against the anthracnose in vivo test at the concentration of 50 ${\mu}L/mL$ when compared to the fungicide containing carbendazim (40%) and kasugamycin (3.45%).