• Weed & Turfgrass Science
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• v.2 no.4
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• pp.387-394
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• 2013

The Rhizoctonia blight causing by Rhizoctonia spp. is an important disease of turfgrass, requiring fungicide application to maintain acceptable conditions for turfgrass good qualities in the golf course. The experiment was conducted to determine the mean 50% effective concentration inhibiting mycelial growth ($EC_{50}$) value of to flutolanil, pyraclostrobine and hexaconazole to Rhizoctonia solani AG-1 IB, Rhizoctonia cerealis and Rhizoctonia solani AG2-2IV isolated from Gyeongbuk province of Korea in vitro. Five discriminatory concentrations of each fungicide were used to detect in vitro sensitivity. The mean of $EC_{50}$ values to three systemic fungicides was the lowest isolate of R. solani AG-1 IB. However, the sensitivity of fungicides to Rhizoctonia solani AG2-2IV were higher mean $EC_{50}$ value of 0.026 ${\mu}g\;a.i.\;ml^{-1}$ of pyraclostrobine and 0.044 ${\mu}g\;a.i.\;ml^{-1}$ of flutolanil. R. cerealis was the lowest sensitivity to hexaconazole which was an average $EC_{50}$ value of 0.022 ${\mu}g\;a.i.\;ml^{-1}$. Inhibition of mycelial growth rate (%) by three combine fungicides using the $EC_{50}$ value of each fungicide was the highest R. solani AG2-2IV. Results of this study were may confirmed in vitro response fungicide of three Rhizoctonia species for control of Rhizoctonia blight in the field.

• Research in Plant Disease
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• v.7 no.1
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• pp.31-36
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• 2001

To establish an effective chemical control strategy against powder mildew of sweet pumpkin (Cucurbita maxima Duchesne) caused by Sphaertheca fuliginea, screening of effective fungicides and determination of their application times were conducted. Powdery mildew caused by S. fuliginea began to occur at about 80 days after transplanting and continuously increased until harvesting in Korea. Systemic fungicides, such as difenoconazole, triforine, bitertanol, and triflumizole, were effective for controlling powdery mildew, showing control efficacies of about 80-90%. When the fungicide triflumizole was applied 3 or 4 times from the beginning day of the disease at 10-day intervals, about 92.0% and 94.6% of disease control and yield increase of 7% and 9% were obtained, respectively. Therefore, the proper application of triflumizole for controlling powdery mildew of sweet pumpkin must be done more than 3 times.

• Research in Plant Disease
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• v.10 no.1
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• pp.69-72
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• 2004

The control activity of isoprothiolane and tricyclazole mixed with carbosulfan, and probenazole by the nursery treatment was performed against rice leaf and neck blast caused by Magnaporthe grisea. In the paddy field, three fungicides showed good activities against leaf blast 3 months after nursery treatment. Especially the activity of tricyclazole against leaf blast gradually increased by the laps of time to 85.5％, which was assessed at 6 September,2003. Although the control value of isoprotholane and tricyclazole mixed with carbosulfan against neck blast was 47.5％ and 61.1％, respectively, probenazole showed a very high activity against not only leaf blast but also neck blast, of which that was 91.2％. No phytotoxicity was observed in all the treatments after transplanting rice seedling in the paddy field. Based on these results, three systemic fungicides tested in this study showed such a good potential that they might be used to formulate the nursery treating granule.

• Research in Plant Disease
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• v.11 no.1
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• pp.39-42
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• 2005

Powdery mildew, caused by Sphaerotheca aphanis var. aphanis, is an economically significant disease of strawberry in Korea. When powdery mildew is not controlled adequately, it often spreads rapidly through strawberry plants and damage is associated with reduced yields. Proper timing of fungicide applications is, therefore, essential for effective disease control. This study evaluated the efficacy by application schedule of fungicides before harvest stage for preventing powdery mildew in 2001-2003. The systemic fungicides, azoxystrobin, kresoxim-methyl, and cupper fungicide DBEDC were applied preventively during the first part of the cultivating season. Preventative applications of DBEDC by dipping treatment before transplanting and kresoxim-methyl by foliar spray before blooming stage were one of the most effective control schedule tested to prevent and manage this disease. This research demonstrated the significance of application time to control of powdery mildew, particularly provided elimination unnecessary sprays of agrochemicals and reduction costs for strawberry growers.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.341-348
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• 2016

Residual patterns of fungicides fludioxonil and metconazole applied 2 or 3 times on wheat were investigated with consideration for their distribution rates in each compartment of wheat. Wheat samples collected at harvesting day were divided into three compartments such as grain, hull and straw, and the pesticide residue analysis was individually carried out to such compartments of wheat. The analytical methods of fungicide residues in wheat were acceptable, with recoveries of 84.3 to 113.3% and correlation coefficients of 0.1 to 4.7%. Due to the systemic characteristics, the residual amounts of metconazole in the grain part of wheat were greater as 0.13~0.17 mg/kg than those amounts (0.01-0.03 mg/kg) for fludioxonil. To absolute residue amounts of the fungicides in one wheat plant, their distribution rates in each compartment of wheat were the highest in straws (68.5-70.7%), followed by hulls (29.0-31.0%) and grains (0.2-0.8%).

• Korean journal of applied entomology
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• v.15 no.2 s.27
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• pp.57-60
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• 1976

Experiments were carried out to determine the effectiveness of a new systemic fungicide EL-291 (5-Methyl-1, 2,4-triazolo (3,4-b) benzothiazole) for the control of rice blast disease in greenhouse and paddy field. The efficiency of EL-291 was much greater when applied before inoculation than when applied after inoculation. Kasugamin and Benlate were most effective as eradicants. For control of leaf blast, effectiveness of EL-291 was not significantly different than either Kasugamin or Benlate. However, EL-291 was considered more economical and reliable than either Kasugamin or Benlate. EL-291 required only a single foliar application or a transplant root soak, whereas two applications of the other fungicides were required. EL-191 was also more effective against panicle blast when applied only once, compared with two applications of Kasugamin or Benlate. The highest riceyields were obtained in plots treated with EL-29l.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.210-216
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• 1995

Alternaria spp.were predominantly isolated from the abnormal leaf spot lesions of pear cultivars Niitaka and Nijiiseiki. Alternaria isolates from the cultivar Niitaka were not pathogenic to both cultivars, but the isolates from the cultivar Nijiiseiki developed typical lesions of black leaf spots and were identified as A. kikuchiana. However, no typical abnormal leaf spot lesions were produced by the Alternaria isolates. Foliar spray of twelve different agrochemicals including lime sulfur, either alone or in combinations, with 7 times applications from April to July failed to reduced the disease development. Application of 17 different pesticides including fungicides, insecticides and herbicides currently used in pear orchards did not cause leaf injury similar to the abnormal leaf spot. Simulated acid rain of as low as pH 3.0 did not incite any leaf lesions alike the abnormal spot lesions. Mineral contents in the leaves of both cultivars did not differ significantly between the healthy leaves and those with abnormal leaf spots. When cuttings of pear tree were obtained in February from newly emerged twigs of the healthy or the diseased trees of Niitaka and planted in sand in the greenhouse, only those from the diseased trees developed typical leaf lesions of the abnormal spot. These results indicate that abnormal leaf spots are caused by unknown systemic agents in pear trees, rather than by Alternaria spp., chemical injury or acid rain.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.103-108
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• 1998

The Canadian production of American ginseng (Panax quinquefolius L.) occurs mainly in Ontario, British Columbia and the Atlantic provinces. Although ginseng is a profitable crop, its successful production is dependent on careful consideration of cultural management f include site selection, site preparation, seed selection and handling, shading actors which and mulching, pest and nutritional management, and handling of harvested crops. Diseases of particular concern in Atlantic Canada are root rots caused by Phytopkthora cactorum, Cylindrocarpon destructans and Fusarium sp. Recently two systemic fungicides (metalaxyl and fosetylal) were registered; however, growers in Atlantic Canada have experienced metalaxyl resistance resulting from the reliance on this single compound for the control of Phytophthora sap. Current research being conducted on alternative control of these diseases will be discussed. In weed control research, 2, 4-D, MCPA, clopyralid have continued to show promise for weed contro1 at low rates. In trials to evaluate non-selective herbicides as post-senescence or pre-emergence in ginseng, glyphosate (Round-up) provided control of perennials as well as willowherb and lambsquarters. In phytoxicity trials, ginseng significantly tolerated grass herbicides, including clethodim, rimsulfuron, trakloxydim, nicosulfuron and fenoxyprop. For broadleaf herbicides, significant tolerance was shown for bromoxynil, thifensulfuron methyl, flumetulam/clopyralid, thifensulfuro/tribenuron. Disease and weed management of ginseng in Atlantic Canada will be discussed.

• Mycobiology
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• v.50 no.5
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• pp.269-293
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• 2022

Oomycete pathogens that belong to the genus Phytophthora cause devastating diseases in solanaceous crops such as pepper, potato, and tobacco, resulting in crop production losses worldwide. Although the application of fungicides efficiently controls these diseases, it has been shown to trigger negative side effects such as environmental pollution, phytotoxicity, and fungicide resistance in plant pathogens. Therefore, biological control of Phytophthora-induced diseases was proposed as an environmentally sound alternative to conventional chemical control. In this review, progress on biological control of the soilborne oomycete plant pathogens, Phytophthora capsici, Phytophthora infestans, and Phytophthora nicotianae, infecting pepper, potato, and tobacco is described. Bacterial (e.g., Acinetobacter, Bacillus, Chryseobacterium, Paenibacillus, Pseudomonas, and Streptomyces) and fungal (e.g., Trichoderma and arbuscular mycorrhizal fungi) agents, and yeasts (e.g., Aureobasidium, Curvibasidium, and Metschnikowia) have been reported as successful biocontrol agents of Phytophthora pathogens. These microorganisms antagonize Phytophthora spp. via antimicrobial compounds with inhibitory activities against mycelial growth, sporulation, and zoospore germination. They also trigger plant immunity-inducing systemic resistance via several pathways, resulting in enhanced defense responses in their hosts. Along with plant protection, some of the microorganisms promote plant growth, thereby enhancing their beneficial relations with host plants. Although the beneficial effects of the biocontrol microorganisms are acceptable, single applications of antagonistic microorganisms tend to lack consistent efficacy compared with chemical analogues. Therefore, strategies to improve the biocontrol performance of these prominent antagonists are also discussed in this review.

• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.269-277
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• 2011

Recent outbreak of new diseases and pests which were introduced from abroad, seriously hampered both quality and safety of paprika fruits. This study has been carried out to aid an establishment of guideline for safe use of pesticides and reduction of their residues on paprika. Systemic fungicides boscalid and pyraclostrobin of either mixed (a.i.; 13.6+6.8%) or single (a.i.; 47 and 18.8%, respectively) water dispersible granule formulation(WG) products were sprayed with recommended or double dosage on paprika grown in green house at March and June. To draw pre-harvest residue limit, residues of each fungicide were analyzed from fruits collected eight times from 18 to 1 day pre-harvest. The biological half-lives of both boscalid and pyraclostrobin in mixed formulation in March and June were slightly shorter than those of single formulation which ranged from 14.4 to 20.1 days. Residue levels of both fungicides of single formulation in fruits in June were about one lower compared to those in March. However, application of double dosage frequently exceeded MRLs from fruits grown both seasons. These results showed that residue levels on fruits persisted longer period of time, more than two weeks, and so the case applied in winter season. The dissipation of fungicides on leaves and fruits was compared. The distribution of both fungicides in leaves was 20-200 times higher than that of fruits and persisted up to 18 days of pre-harvest period at the concentration of 10-40 ${\mu}g\;g^{-1}$. This study indicated that the mixed formulation product exhibited low residues in fruits, but high and long enough to pathogen growth in leaves.