• Korean Journal of Microbiology
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• v.50 no.3
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• pp.201-209
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• 2014

This study was carried out in order to develop a biological control of anthracnose of red pepper caused by fungal pathogens. In particular, this study focuses on the Colletotrichum species, which includes important fungal pathogens causing a great deal of damage to red pepper. Antagonistic bacteria were isolated from the soil of pepper fields, which were then tested for biocontrol activity against the Colletotrichum gloeosporioides anthracnose pathogen of pepper. Based on the 16S rRNA sequence analysis, the isolated bacterial strain CS-52 was identical to Bacillus sp. The culture broth of Bacillus sp. CS-52 had antifungal activity toward the hyphae and spores of C. gloeosporioides. Moreover, the substances with antifungal activity were optimized when Bacillus sp. CS-52 was grown aerobically in a medium composed of 0.5% glucose, 0.7% $K_2HPO_4$, 0.2% $KH_2PO_4$, 0.3% $NH_4NO_3$, 0.01% $MnSO_4{\cdot}7H_2O$, and 0.15% yeast extract at $30^{\circ}C$. The inhibition of spore formation resulting from cellulase, siderophores, and indole-3-acetic acid (IAA), were produced at 24 h, 48 h, and 72 h, respectively. Bacillus sp. CS-52 also exhibited its potent fungicidal activity against anthracnose in an in vivo test, at a level of 70% when compared to chemical fungicides. These results identified substances with antifungal activity produced by Bacillus sp. CS-52 for the biological control of major plant pathogens in red pepper. Further studies will investigate the synergistic effect promoting better growth and antifungal activity by the formulation of substances with antifungal activity.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.109-120
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• 2012

This study was conducted to monitor 284 pesticides residue level in 2,914 commercial agricultural products in the northern area of Seoul in 2011 by the multi class pesticide multiresidue analysis methods in Korea Food Code using GC, HPLC, GC-MSD and, LC-MSD. The detection rate of pesticide residues were 14.8% (431/2,914). The order of agricultural products in which the pesticide residues were detected was perilla leaves 40.0% (28/70), chamnamul 35.5% (11/31), amaranth 30.0% (3/10) and spinach 27.7% (38/137) etc. The percentage of products that exceeded the MRLs (maximum residue limits) were 1.0% (31/431). Those products that exceeded MRLs were ginseng (6), perilla leaves (4), leek (4), welsh onion (3) and sedeum (3) etc. The 59 kinds of the pesticides were detected on this study, 21 pesticides of them were detected over MRLs. Detection rate of fungicides (56.4%) was higher than that of insecticides (42.1%). And procymidone was detected with considerable high frequency. Additionally, residual residual violates pesticides were in the order of tolclofos-methyl, endosulfan, dimethomorph, diniconazole and fludioxonil. According to the agricultural marketing channels, detection and excess rate of them were monitored. Detection and excess rate of samples circulated in agricultural traditional market were highest. The estimated daily intakes (EDI) of the pesticides were compared to personal acceptable daily intakes (PADI) in order to risk assessment by food consumption. Diazinon in Korean cabbage showed the highest %ADI, 2.9901 and others showed below 3.0 %ADI. Overall, these results indicate that residue levels of pesticides detected were evaluated as safe.

• Research in Plant Disease
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• v.15 no.2
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• pp.94-100
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• 2009

These experiments were conducted to improve the effect of seed disinfection on rice seed severely infected Bakanae disease by seed soaking into mixed solution of prochloraz EC and fludioxonil FS. We investigated the effects of various concentrations of two fungicides mixed solution on spore germination and mycelial growth of Fusarium fujikuroi. Mycelial growth was inhibited 100% at $10{\mu}g$/ml of prochloraz and 33.3% at $80{\mu}g$/ml of fludioxonil. Spore germination was inhibited 81.4% at $40{\mu}g$/ml of prochloraz. Interestingly, mixed solution of $5{\mu}g$/ml or $10{\mu}g$/ml of each fungicide inhibitied 100% of mycelial growoth and 99.2% of spore germination, respectively. Severely infected rice seeds soaked into mixed solution composed of $125{\mu}l$/ml of prochloraz and $50{\mu}l$/ml of fludioxonil showed 2.1% of disease symptoms compared to 20.4% of prochloraz $125{\mu}l$/ml, but higher concentrations of prochloraz decreased the seedling stand rate. When the seed soaking time was longer and temperature was higher, control effect on Bakanae disease was improved, but seedling stand was lower about 80% over $35^{\circ}C$.

• Research in Plant Disease
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• v.22 no.3
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• pp.145-151
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• 2016

Chemical fungicides have reduced Fusarium head blight (FHB) severity. However, by the effects of fungicide residues, they can only be used up to 30 days before time of harvest. Therefore, the development of new biofungicides that are applicable until harvest is required. In order to select plant extracts having antifungal activity against Fusarium graminearum for the control of FHB, we investigated the inhibitory effects of 225 medicinal plant extracts on spore germination of F. graminearum. Of these plant extracts, the methanol extract of Cirsium japonicum (CJ) roots showed the strongest antifungal activity. Through solvent partitioning, repeated column chromatography, and spore germination bioassay, two chemicals were purified and then their chemical structures were identified as ciryneol C (CC) and 1-heptadecene-11,13-diyne-8,9,10-triol (HD-ol) which are polyacetylene substances. Two active compounds effectively inhibited the germination of F. graminearum macroconidia; HD-ol ($IC_{50}$ of $3.17{\mu}g/ml$) showed stronger spore germination inhibitory activity than that of CC ($IC_{50}$ of $28.14{\mu}g/ml$). In addition, the wettable powder type formulation of ethyl acetate extract of CJ roots suppressed the development of FHB in dose-dependent manner, with control values of 78.92% and 31.56% at 250- and 500-fold dilutions, respectively. Combining these findings suggest that the crude extract of CJ roots containing polyacetylene compounds could be used as botanical fungicide for the control of FHB.

• Korean Journal of Environmental Agriculture
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• v.17 no.2
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• pp.107-116
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• 1998

In an effort to reduce artifically the residual pesticides on crop and soil by accelerated photolysis,some 40 among the naturally occurring and synthetic coumpound were screened for photosensitization and/or photocatalysis and six promising chemicals were selected.The fungicides and the four selected photosensitizers and/or photocatalyst (PS) were applied to each crop.The results obtained are summarized as follows. 1. The wavelengths of maximum absortion (${\lambda}$max) and the molar absorptivites (${\varepsilon}$max) of procymidone,vinclozolin,and carbendazim in acentone were all 209 nm and 853,854,and 8740 respectively. 2. Of the 40 naturally-occuring and synthetic compounds screened,six promising ones were selected and designated as PS-1 (aromatic ketone),PS-2(aromatic amine)PS-3(quinone) ,PS-4 (inorganic compound),PS-5(organic acid salt) and PS-6(semiconductor photocatalyst). 3. In the accelerated photolysis of pesticide in soil by applying PS ,procymidone was decoposed rapidly by virtue of PS-2,being 59% of the control 3 days after application. 4. The vinclozolin residue in soil was reduced to 71% and 21% of the control 1 and 15 days,respectively,after PS-2 application. 5. The photolysis of carbendazim in soil was not accelerated by any of the PS tested. 6. The pesticide residues on the crop were prominently reduced by PS application.The procymidone residue on tomato was reduced to 47% of the control 15 days after PS-1 application and that on red pepper reduced to 57% 15 days after PS-2 application. 7. Vincrozolin residus remaining on tomato 1 and 15 days after PS-2 application were 38% and 56% of the control whereas those on the red pepper were 82% and 64%,respectively. 8. PS-2 was the most effective for the accelerated photolysis of carbendazim residues remaining on tomato, whereas on red pepper, the four of PS tested were all effective, but did not make much difference between them. This might be due to the shielding of sunlight by the leaves of red pepper not to exert the photosensitizing effect of PS-2 to the full.

• Korean Journal of Environmental Agriculture
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• v.36 no.4
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• pp.230-240
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• 2017

BACKGROUND: To evaluate residues of environmentally concerned pesticides in water system, this monitoring was conducted over three rivers. The residual characteristics and discharging condition of these residues on water system was investigated. METHODS AND RESULTS: Total twenty nine sampling sites were selected through main streams and branch streams of Keum, Mangyung and Dongjin rivers, and the water samples from them were regularly collected one month interval, especially biweekly from May to August in 2002. Of the pesticides monitored, six fungicides which include hexaconazole, isoprothiolane and iprobenfos were detected with frequencies of 0.3-50.9% and in their residue level of $0.1-4.7{\mu}g/L$. Sixteen insecticides which include nine organophosphoruses, three carbamates, endosulfan, cypermethrin, buprofezin and fipronil were detected with frequencies of 0.3-32.5% and in their residue level of $0.01-2.8{\mu}g/L$. Nine herbicides which include alachlor molinate, anilofos, butachlor, dimepiperate, metolachlor, oxadiazon, pretilachlor and thiobencarb were detected with frequencies of 0.8-22.9% and in their residue level of $0.01-9.07{\mu}g/L$. CONCLUSION: Detection frequencies and residue levels of insecticides and herbicides were the highest in waters sampled in May and June. Almost pesticides detected were for the paddy rice and their residue levels were very low to compare with standard values.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.1-7
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• 2010

To revise the dithiocarbamates residue analysis method and survey the residues in agricultural products that were treated with these fungicides in Korea, we purchased 20 types of foodstuffs (rice, potato, cabbage, apple etc.) from markets in five major cities. 236 samples of the purchased foodstuffs were then analyzed for the presence of dithiocarbamates by HPLC/UV and HPLC/APCI-MS. The $R^2$, LOD and LOQ in the range of 0.5-107.3 mg/L were as follows: DCC: y=174.34x+18.315, $R^2=0.9999$, 0.01 mg/L, and 0.04 mg/L; EBDC: y=227.38x-14.715, $R^2=1.0000$, 0.01 mg/L and 0.02 mg/L; PBDC: y=38.46x-21.412, $R^2=0.9999$, 0.04 mg/L, and 0.1 mg/L; ETU: y=52.752x-4.4819, $R^2=0.9998$, 0.02 mg/L and 0.03 mg/L; PTU: y=128.28x+4.4624, $R^2=0.9998$, 0.02 mg/L, and 0.04 mg/L. The levels of DDC, EBDC, PBDC, ETU and PTU in 20 agricultural products fortified to 10.0-107.3 mg/L ranged from 61.7-117.5%, 65.3-110.1%, 61.5-109.6%, 69.3-116.3% and 70.2-97.2%, respectively. Overall, dithiocarbamates were detected in 100 samples and the detection ratio was 42.4%. Among these, only 3 samples (1.3%) of Lycii fructus had residue levels that were above the action limits, while the remaining samples (233 samples) contained levels of dithiocarbamates below the detection limit or below the Korea MRLs (Maximum Residue Limits).

• Korean journal of applied entomology
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• v.25 no.3 s.68
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• pp.139-149
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• 1986

These experiments were performed to investigate the effects of sublethal doses of fungicides (validamycin A 3 Sp and neoasozin 6.5 Lq) and insecticides (diazinon 34Ec and decamethrin 1Ec) on the possible ways to the resurgence of brown planthoppers (BPH) (Nilaparvata lugens $St{\aa}l$). The possible factors tested in this experiment were fecundity of BPH, longevity, egg-hatchability, amount of honeydew excreted, population build-up following the pesticide treatments in the next generation, and hopperburn rate of potted rice plants. Among the insecticides tested, the applications of diazinon and decamethrin in rice fields may induce the BPH resurgence and accelerate the hopperburn of rice plants through stimulating the fecundity, increasing the adult longevity, promoting the feeding activity and causing the positve population build-up of the BPH

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.376-382
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• 2015

Dollar spot, caused by Sclerotinia homoeocarpa, is the major disease in cool-season turfgrasses. Understanding the distribution of this pathogen in soil and thatch is important to developing disease control strategies. In this study, toothpicks were used to detect S. homoeocarpa in the turfgrass canopy, thatch, and soil at different distances from dollar spot infection centers. The effect of penetrant and contact fungicide applications with different water volumes on distribution of S. homoeocarpa was also investigated. S. homoeocarpa was detected in 100% of samples taken from the leaf canopy, 83.3% in thatch area, and 0% in the soil from within the infection center. S. homoeocarpa was isolated in 100% of samples taken from the edge of the infection center, but was only detected in 13% of the samples taken at 1.5 cm away from the infection center edge. S. homoeocarpa was isolated at a higher frequency in the propiconazole treated plots than those treated with chlorothalonil and was not detected in leaf canopy samples when either fungicides was applied with 6.78 L of water. In conclusion, the toothpick-aided detection technique has improved our understanding of S. homoeocarpa epidemiology and could be used as a diagnostic tool to detect for fungicide resistance on golf courses.

• The Korean Journal of Mycology
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• v.41 no.3
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• pp.172-180
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• 2013

Grey mold infection rate in tomato was investigated with the inoculation of dead flowers on Botrytis selective media. The grey mold infection rate of flower after fruiting were higher in the order of after 45 days, after 25 days, and fruiting day with 100%, 87% and 65%, respectively. The number of infected flowers were increased with time increase after the flowering before fruiting. BSM (Botrytis selective medium) was used to check grey mold infection rate depending on the flowering stage and cultivar. Grey mold infection rate depending on the flowering stage was similar in all the beef-tomato cultivar as 1.5~5% at preflowering, 1.5~45% at flowering and 75~90% at fruiting. On the other hand, cherry tomato cultivar "KoKo" had lower infection rates of 0~3.5% at pre-flowering, 10~30% at flowering and 20~50% at fruiting. These resulted from the fact that beaf-tomato cultivar have much bigger flowers and larger amount of pollens compared to those of cherry tomato cultivar. The amounts of falling pollens of Botrytis spp. were checked for beaf-tomato cultivar and cherry tomato cultivar using BSTM. The amounts of falling pollens were increased as growth period was extended, and the amount of spores increased rapidly during the outbreak of grey mold. Twelve field trials in Buyeo and Iksan areas showed that Fluazinam, and Diethofencarb+Carbendazim were effective fungicides to control tomato grey mold, and these results were similar to those of field trials with BSTM. This is the first report of Fluazinam as a effective fungicide for the control of grey mold of tomato even though it has not been registered yet for the control of gray mold in tomato.