• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.59-67
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• 1992

The duration of raising seedling of infant rice seedling(IRS) in machine transplanting is 8 to 10 days. This experiment was conducted to investigate the minimum duration of IRS's raising seedling and its method by the combination of several treatments such as plant growth regulator, root-break-seat and temperature. The rice seeds of Hwaseongbyeo was soaked in the solution of metalaxyl for 24 hours at room temperature. Metalaxyl (25% wettable powder), a fungicide, was used in 1, 000 times dilution as a promting substance on the root-mat formation of IRS. The application of fungicide in the nursery soil for the controlling of damping-off and physiologyical seedling rot was omitted due to the metalaxyl seed-soaking treatment. Seeding rate was 220g per seed tray (30$\times$60$\times$3cm). To promote the root-mat formation of IRS, the sheets of polyethylene vinyl and absorptive paper were placed bottom the seed tray. The root-mat formation of IRS was promoted at higher temperature and longer duration of raising seedling. The metalaxyl-treated seeds markedly increased the root length and rooting activity of IRS as compared with the control, thus the root-mat formation was excellent. The absorptive paper with polyethylene vinyl as root-break-seat showed a better root-mat formation compared with control, polyethylene vinyl, alone. The minimum duration of raising seedling of IRS was 5 days after sowing based on the root-mat formation and seedling height under the condition of metalaxyl seed treatment, absorptive paper with polyethylene vinyl as a root-break-seat and the raising seedling temperature 30/2$0^{\circ}C$ (day /night).

• Journal of Ginseng Research
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• v.33 no.4
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• pp.311-315
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• 2009

Potassium phosphonate inhibited less mycelial growth of Phytophthora cactorum in vitro than metalaxyl-M. But the net protection rate in leaflet test and whole plant pot test was greater in potassium phosphonate than metalaxyl-M. P. ginseng appeared to have an induced resistance against P. cactorum with phosphonate around 50~100 ppm.

• Mycobiology
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• v.31 no.4
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• pp.229-234
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• 2003

A total of 24 isolates of Phytophthora infestans were tested and analyzed for their resistance to metalaxyl fungicides. Sensitivity to metalaxyl was determined by growing isolates on 20% V8 medium amended with 0, 5, and 100 ${\mu}g/ml$ metalaxyl. Four isolates among the 24 tested were resistant to metalaxyl. Eleven isolates were intermediate and nine isolates were sensitive. Amplified fragment length polymorphism(AFLP) assay was used to identify the amplification products of resistant isolates. As a result, selected fragments were cloned, sequences and primer pairs were developed which linked to metalaxyl insensitivity in P. infestans using competitive PCR.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.9
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• pp.1258-1264
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• 2009

The removal effects of two commonly used pesticides of Bifenthrin and Metalaxyl during preparation and fermentation of kimchi were studied. The two pesticides were applied to Baechu cabbages intentionally for 20 seconds; the applied amounts of Bifenthrin and Metalaxyl were 3.02$\pm$0.09 ppm and 6.79$\pm$0.17 ppm, respectively. The Baechu cabbages were washed by water 3 times. Then the residual amounts of the two pesticides of Bifenthrin and Metalaxyl were measured and the removal rates were 21.7% and 16.1%, respectively. When Baechu cabbages were brined with 10% salt solution for 12 hours after the application of the two pesticides, the removal rates significantly increased to 98.7% and 60.8%, and when brined and washed 3 times by water, the removal rates even more increased to 99.7% and 73.4% respectively. Then we made kimchi and investigated the quantities of the residual pesticides during the fermentation at $4^{\circ}C$ for 3 weeks. The residual amounts of the pesticides in kimchi decreased in a time dependent manner, finally the amounts of the pesticides to 0.35$\pm$0.04 ppm and 0.48$\pm$0.06 ppm while the removal rates of the two pesticides were 57.8% and 81.0%, respectively. When the kimchi was fermented at $4^{\circ}C$ and $10^{\circ}C$ for 3 weeks, the removal rates of Bifenthrin were 57.8% and 72.2% and those of Metalaxyl were 81.0% and 85.6%, respectively. Consequently, it appeared that the residual pesticides can be removed during preparation, especially brining; the fermentation process of kimchi also removed the residual pesticides effectively, especially at higher temperature and long period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.57-64
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• 1991

This experiment was conducted to elucidate the effect of plant growth regulators (PGR) on the root -mat formation of infant seedling (8- to 10-day-old seedling) of rice in machine transplanting. The rice seeds of Odaebyeo were socked in water with different concentrations of PGRs for 48 hours at room temperature. Seeding rate was 220 g per seed tray (30x60x3cm). Metalaxyl (25% wettable powder) was used for a fungicide. Generally, the metalaxyl-treated seeds markedly promoted the root growth of the rice seedling, while tetracy-cle, pachlobutrazol and NTN -821 reduced the seedling height and root length, and thickened the shoot diameter at higher concentation levels. Tetracycle decreased root length of the rice seedlings but increased root number per seedling, and root-mat formation was poor. Whereas, metalaxyl concentrations of 200 and 1,000 ppm markedly increased root length and number of root hairs without decreasing root number, thus root-mat formation was excellent. The optimum concentration of metalaxyl seed treatment to increase the root-mat formation of infant seedling of rice was about 200 ppm. Metalaxyl seed treatment could be advanced one to two days of the duration of root-mat formation compared with control.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.88.2-89
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• 2003

Changes of control efficacy of metalaxyl to potato late blight caused by Phytophthora infestans were examined in potato fields from 2001 to 2003. In 2001 and 2002, control efficacy of metalaxyl was similar to those of dimethomorph and ethaboxam. However, the control efficacy of metalaxyl were decreased to 50.3％ in 2003. Total 366 isolates of P infestans obtained from several areas in Korea from 2001 to 2003 were examined for changes of sensitivity to metalaxyl. About 6.8％ of fungal isolates examined in 2001 were sensitive, 84.1％ were intermediate resistant, 9.1％ were resistant to metalaxyl. Among the isolates collected in 2002, 3.9％ were sensitive, 75.6％ were intermediate resistant, 20.6％ were resistant to the chemical. However, among the isolates obtained in 2003, 55.9％ were intermediate resistant, 44.1％ were resistant, but none of the isolates tested were sensitive. Both A1 and A2 mating type isolate were isolated in 2002∼2003. However, all isolates collected in 2001 were A1 mating type. About 87.5％ of the isolates collected in 2002, 89.8％ In 2003 were determined as A1 mating type. The majority of the p. infestans isolates were A1 mating types. Changes of control efficacy of metalaxyl to potato late blight might be caused by the occurrence rate of moderately resistant isolates within A1 mating type.

• The Plant Pathology Journal
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• v.19 no.3
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• pp.143-147
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• 2003

Sensitivity of Phytophthora infestans isolates to fungicides metalaxyl and ethaboxam in Korea was examined with 260 isolates for 3 years (9 isolates in 2000,93 isolates in 2001, and 158 isolates in 2002). Both Al and A2 mating types were found from the isolates collected for 3 years. Al mating type was dominant in the population with 8 isolates (88.9%) in 2000, 84 isolates (89.4%) in 2001, and 138 isolates (87.3%) in 2002. Only some isolates from diseased tomatoes in Buyergun and diseased potatoes in Pyeongchanggun were of the A2 mating type. As for metalaxyl sensitivity, 77.0% of the isolates were moderately resistant with 8 isolates (88.9%) in 2000, 73 isolates (77.7%) in 2001, and 120 isolates (75.9%) in 2002. Meanwhile, those found resistant were 1 isolate (11.1%) in 2000, 16 isolates (17.0%) in 2001, and 33 isolates (20.9%) in 2002. Only 5 isolates (3.2%) were sensitive to metalaxyl in 2002. There was no significant difference in the sensitivity among years. As for ethaboxam, no isolate was able to grow at 5.0 $\mu\textrm{g}$ /ml, and only four isolates (1.5 %) grew at 1.0 $\mu\textrm{g}$ /ml with heavy retardation compared with the untreated control. Based on these 3-year results, the minimum inhibitory concentration (MIC) of ethaboxam to p. infestans was determined to be 0.2-1.0 $\mu\textrm{g}$ /ml. Results indicate that resistance development by p. infestans to ethaboxam is not likely to occur in the natural condition. furthermore, there was no indication of cross resistance between metalaxyl and ethaboxam because all the isolates, regardless of classification for their sensitivity to metalaxyl, were not able to grow at 5.0 $\mu\textrm{g}$ /ml of ethaboxam.

• The Korean Journal of Pesticide Science
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• v.7 no.4
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• pp.264-270
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• 2003

To control effectively and safely Phytophthora root rot caused by Phytophthora capsici on tomato in hydroponic culture, tank-mixing method was considered with two pesticides, metalaxyl copper oxychloride 50% WP and dimethomorph dithianon 38% WP. Forty days after transplanting of tomato seedlings, 4 mL of sporangia of P. capsici (about 25 sporangi/mL) per plot was inoculated around tomato plant roots, and at 5 days after inoculation, the pesticides tank-mixed at three dilution levels, 12,500, 25,000 and 50,000, were drenched 1, 2 or 3 times per plot on the culture cube every 15 days for metalaxyl copper oxychloride 50% WP and every 10 days for dimethomorph dithianon 38% WP. During the drenching period, the residue levels of metalaxyl and dimethomorph in hydroponic culture solution were similar to the initial levels but the level of dithianon was drastically decreased from one day after tank-mixing. In tomato drenched with metalaxyl copper oxychloride 50% WP, metalaxyl was detected $0.02\sim0.04$ mg/kg in all diluted plots. Dimethomorph was detected $0.012\sim0.021$, $0.001\sim0.006$ and $0.001\sim0.003$ mg/kg in 12,500, 25,000 and 50,000 times diluted plots, respectively, while dithianon was detected 0.005, 0.003 mg/kg in 12,500 and 50,000 times diluted plots, respectively. The detection levels of three pesticides were far below compared with the levels of Korean MRLs. Incidences of Phytophthora root rot were not found in all the plots, but phytotoxic responses were recognized in the 12,500 times diluted plots of both pesticides. Based on the above results, the drenching of the culture solution tank-mixed with these pesticides could be recommended as a very safe and effective method to control Phytophthora root rot in tomato in hydroponic culture.

• Research in Plant Disease
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• v.20 no.1
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• pp.25-30
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• 2014

Phytophthora infestans was isolated from potato leaves collected from main potato producing areas in Korea during 2009-2011. In 2009, 99 isolates tested were all A1 mating type. Two of 64 isolates in 2010 and two of 78 isolates in 2011 were A2 mating type and they were found only in Miryang area. Among 99 isolates examined in 2009, 13.1% was resistant to metalaxyl, 3.1% was intermediate resistant and 83.8% was sensitive. In 2010, 19.4% of 62 isolates was resistant, 4.8% was intermediate and 75.8% was sensitive. Metalaxyl resistant, intermediate and sensitive isolates collected in 2011 were 23.1%, 9.0% and 67.9%, respectively. Metalaxyl resistant isolates increased mainly in winter cropping areas and seed potato producing areas where fungicides were sprayed more often. Frequencies of isolates showing minimum inhibition concentration of dimethomorph at $1.0-5.0{\mu}g/ml$ were 17.2% in 2009, 19.0% in 2010 and 15.4% in 2011. However, there was no evidence for occurrence of resistant isolate to dimethomorph because no isolate was able to grow at $5.0{\mu}g/ml$.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.34-42
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• 2008

In order to know the residual pattern of some pesticides and predict to the degradation period until below MRL, we experimented chlorothalonil, indoxacarb, lufenuron, metalaxyl and methomyl for Chinese cabbage. They were frequently detected pesticides in Chinese cabbage by NAQS (National Agricultural product Quality management Service) monitoring survey. In this experiment, we sprayed those pesticides 10days before harvest and analyzed 0, 1, 2, 3, 5, 7, 10 day samples to establish logical equation and to calculate $DT_{50}0$. During the cultivating period, the residue amount of chlorothalonil was changed from $55.58\;mg\;kg^{-1}$ (0 day) to $20.08\;mg\;kg^{-1}$ (10 day), $DT_{50}$ was 7.45 days, indoxacarb was $7.85\;mg\;kg^{-1}$ (0 day) to $1.46\;mg\;kg^{-1}$ (10 day), and 4.2 days, lufenuron was $1.57\;mg\;kg^{-1}$ (0 day) to $0.49\;mg\;kg^{-1}$ (10 day), and 5.85 days, metalaxyl was $8.12\;mg\;kg^{-1}$ (0 day) to $0.10\;mg\;kg^{-1}$ (10 day), and 175 days, and methomyl was $11.51\;mg\;kg^{-1}$ (0 day) to $0.80\;mg\;kg^{-1}$ (10 day), and 2.42 days at single dose application, respectively. The $DT_{50}$ of double amount in those pesticides were 9.05 days in chlorothatonil, 7.09 days in indoxacarb, 8.82 days in lufenuron, 3.32 days in metalaxyl, and 2.72 days in methomyl, respectively.