• Korean Journal of Weed Science
• /
• v.16 no.1
• /
• pp.28-35
• /
• 1996

Tetrapion(2,2,3,3-tetrafluoropropionate sodium) has commonly been used for reed(Phragmites communis Trin.) control in uncultivated areas, especially in Japan. As an attempt to establish the screening system for selective herbicide controlling reed, tetrapion was tested as a standard herbicide to various weeds and crops including rice in a greenhouse. Symptoms of yellowing, twisting, stunting, and necrosis were observed in the herbicide-treated plants. The herbicide caused a severe damage on all crops examined, except cotton. Both direct seeded and transplanted rice were also sensitive to the herbicide. Its herbicidal activity was generally higher on grass weeds than on broadleaf weeds. It had a higher herbicidal activity with preemergence treatment than with postemergence treatment. In addition, field and greenhouse experiments were conducted to examine the effect of the herbicide on reed control. Its effect varied with the soil type of the treated field and the growth stage of reed. A relatively high dosage of the herbicide was required to control reed. It had an almost same effect on fairygrass(Miscanthus sinensis Anderss) as on reed. However, reed grown in a greenhouse was effectively controlled by the herbicide, having more effect with preemergence treatment than with postemergence treatment as observed in other plants treated with the herbicide. In conclusion, tetrapion has a great potential as a standard herbicide during the herbicide screening for selective reed control.

• Korean Journal of Soil Science and Fertilizer
• /
• v.27 no.4
• /
• pp.309-314
• /
• 1994

Population changes of serveral bacterial groups and chemical changes of nutrients applied were compared between soils suspensed with pentachlorophenol(PCP) and amended with different nutrients. The number of total bacteria and Gram-negative bacteria were dramatically increased for 1st week, after remained at its maximum level for a short time, decreased gradually in all treatments for 5th week, the rate of decrease were faster at addition of only PCP than at addition of nutrients and PCP. While, the addition of nutrients in the soil suspension containing PCP suppressed the number of PCP-degrading bacteria. The dissipation of PCP were faster at single addition of PCP than at the combined addition of nutrients with PCP. The nutrients added with PCP were rapidly degraded for 1st week, among the nutrients the rate of degration of glucose was faster than that of glutamic acid or glycine. pH values in the suspension showed which addition of nutrients with PCP caused its changes in comparsion with addition of only PCP where changes was slightly.

• Korean journal of applied entomology
• /
• v.10 no.1
• /
• pp.7-12
• /
• 1971

1. The number of Rhizoctonia solani, Pythium debaryanum, Fusarium and Trichoderma was detected by the modification of Boosails special plating method when ginseng seed bed was drenched with Captan, Difolatan, Zineb, Maneb and PCNB at weekly intervals. Pythium debaryanum Hesse was described for the first time on Panax ginseng in Korea. 2. The number of Rhizoctonia solani and Pythium debaryanum was decreased gradually as the geason Progressed, whereas that of Fusarium and rrichcderma was increased. 3, The number of Rhixoctonia solani was greatly reduced by PCNB, and soils treated with other fungicides generally showed less Rhizoctonie solani than in the control. The number of Pythium debaryanum was significantly reduced by Zineb, Maneb, followed by Captan and Difolatan. None of the fungicids reduced the number of Fusarium colonies in the fourth week. Effects of the chemicals on Trichoderma were not statistically significant. 4. More fresh weight of the seedling roots was obtained using Difolatan, Maneb and PCNB. Phytotoxicity was noted with Maneb, Zineb and Captan after the third treatment.

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

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.26 no.2
• /
• pp.179-184
• /
• 1981

The study was conducted to know the differential growth responses of soybean cultivars as affected by various application stages of Metribuzin herbicide, at the University experimental farm of Chonnam Nat'l. Univ, Kwangjoo, 1980. Experimented soybean materials were six cultivars, as Kwanggyo, Dongbuktae, Bongui, Yukwoo 3, Suweon 85, and Suweon 86., . and Laid-out application stages were five as pre-sowing, Pre-emergence, Early Post-emergence, and Late Post-emergence treatment comparing with Control. Results obtained from the study were as follows: Among experimented soybean cultivars, no significantly tolerant cultivar was shown. Highly significant differences in phytotoxicities by Metribuzin treatments were detected among various application stages, and crop tolerances were recognized bigger in order as E. Post-emg. < L. Post-emg. $\ll$ Pre-emg. < Pre-sowing $\leq$ Control. The phytotoxic symptoms of all soybean cuitivars were severely recorded in order of Leaf No. /Plant < Plant height $\ll$ Branch No. /Plant. For the cultivation of most soybean cuitivars, the use of Metribuzin in Pre-sowing or Pre-emergence were recommended, and especially it is expected to follow of more detailed study on soil-incorporation method in Pre-sowing treatment, and rather the tank-mixture system of Metribuzin with others than the mono-application system for the safe-use and enlargement of weeding-spectrum.

• Korean journal of applied entomology
• /
• v.26 no.4 s.73
• /
• pp.261-265
• /
• 1987

Three diffeerent types of symptoms were observed according to the pathogen associated with the rhizomes. The maximum rotting was observed in case when Pythium aphanidermatum was inoculated first followed by Fusarium solani. There was no interaction in case of root knot nematode Meloidogyne incognita and Pythium aphanidermatum. Average per cent germination of the rhizomes were increased significantly in each treatment and maximum in case of Alliette(.25%). The per cent pre & post drenching rotting was minimum in case of Alliette, Burgandy mixture, Dithane-M 45 and Difolatan. These fungicides also increase the yield of rhizome significantly.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.6 no.2
• /
• pp.71-77
• /
• 1986

The field experiment was conducted to evaluate the effect of herbicide treatment (Banvel: 100, 200, U-46: 150, 300, Hedonal: 150, 300, Simazin: 100, 200g/10 a) on change in the botanical composition and dry matter productivity of ladino clover (Trifolium repens L.) dominated pasture mixtures. The experiment was laid down as a randomized block design with 4 replications at experimental field of Livestock Experiment Station in Suweon from 1983 to 1985. The results obtained are summarized as follows: 1. Against ladino clover in mixie grass-clover swards Banvel, U-46 and Hedonal gave good control. The percentage of ladino clover under herbicide tratment decreased to about 1-2%(Banvel), 11-18%(U-46) and 22-31%(Hedonal), respectively, while it increased to 71% in untreated pastures. However, in the second year this trend stated to reverse and occurred clover dominance again in U-46 and Hedonal application, while those remained approximately constant until end of the years under Banvel treatment. Simazin is to be not recommended. 2. The best time for herbicide treatment was found to be late summer before autumn sown 20-25 days. When it applied in early summer weed infestigation by Digitaria spp., Echinochloa spp. and other species was a severe problem. 3. Emergence and early development of introduced pastures were less satisfactory, if it oversown immediatley after herbicide treatments due to its phytotoxical damage. Residual chemicals remained about 7-10 days in topsoils. Perennial ryegrass and orchardgrass were slightly less tolerant than the other species. 4. In dry matter, taken as average of three year results, Banvel applied pastures produced the remarkably high yield of 1023 kg/10 a, which is as much as 44% higher than that of untreated plot. Dry matter yields under U-46 and Hedonal treatment were 842 and 811 kg/10 a, respectively. 5. Weender components and net energy concentration were affected by change in the botanical composition. Crude protein and NEL value were slightly higher in clover dominance than those in herbicide treatments. Total yields of net energy lactation, however, were the highest in Banvel application with 5401 MJ and the lowest in untreatment with 3889 MJ-NEL/10 a DM.

• Korean Journal of Environmental Agriculture
• /
• v.2 no.1
• /
• pp.1-5
• /
• 1983

A study was undertaken to investigate the persistence of diazinon in two different soils under field conditions. Half-life of diazinon granule(5%) incorporated into soils at a rate of 0.15 ㎏ a.i./l0a was 11 and $9{\sim}12$ days in Suweon and Iri soil under field conditions, respectively. Diazinon residues in brown rice and rice straw harvested from Suweon field were also evaluated by scheduled application intervals. On the basis of maximum residue limit of diazinon in brown rice, it is recommended that the insecticide could be applied upto 15 days before harvest at the limit of 4 spraying times.

• Korean journal of applied entomology
• /
• v.19 no.2 s.43
• /
• pp.79-83
• /
• 1980

The toxicities of some soil insecticides were evaluated in terms of the tolerance to various larval-ins tars of the common cutworm (Agrotis fucosa Butler) using topical application method in the laboratory. $LD_{50}$ values(ug/larva) were determined by the probit analysis and the tolerance-values were obtained with '$LD_{50}$ values for from 2nd-to 6th-instars/$LD_{50}$ values for first-instars.' The relative toxicities of the insecticides were 31so compared with the $LD_{50}$ values for the instars. The degree of tolerance was greatly increased as the larval instar advanced; the ranges of tolerance between the first-and 6th-instar larvae to the insecticides phoxim (Volaton), diazinon, chlorpyrifos (Dursban), carbofuran (Curaterr) and Mocap were 251.6, 126.6, 97.5, 44.3, and 18.7 times, respectively. The average relative toxicities of the insecticides for the instars indicated that the toxicity of phoxim was the greatest and following carbofuran, chlorpyrifos, Mocap and diazinon.

• Applied Biological Chemistry
• /
• v.20 no.1
• /
• pp.58-65
• /
• 1977

A laboratory experiment was carried out with loamy paddy soily under Hooded condition to study the effects of some pesticides on the decomposition rate of urea and the transformation of nitrogen. The pesticides used in this study are ten kinds, which are usually applicable for rice cropping. The soil was treated with 200ppm of fertilizer urea-N and different levels of pesticides and then incubated at $28{\pm}1^{\circ}C$ for two weeks. The kinds of pesticides used in this study were three kinds of herbicides (2,4-D, Machete and TOK), three kinds of fungicides (Rabcide, Neo-asozine and Phenazine) at the levels of 20,100 and 200ppm and four kinds of insecticides (Birlane, Diazinon, Sumithion and Bux) at the levels of 50,250 and 500ppm. respectively. The results obtained may be summarized as follows. 1. The treatments of herbicides and fungicides show little effect on the decomposition rate of urea at the levels of 20 and 100ppm, but by the treatment of 200ppm it was retarded markedly after one day incubation aside from Rabcide and Neo-asozine. The decomposing rate of urea was inhibited weakly by the treatment with 250ppm of Sumithion and Bux, however, 500ppm of all kinds of insecticides treated in this study brought about strong inhibitory effect (over 50%) after only one day incubation. The applied urea was disappeared nearly completely in three days in all cases with and without pesticides. 2. The production of ammonium-N was increased with the increase of pesticide concentrations gradually through two weeks and otherwise in the control sample a loss of inorganic-N resulted in about 20% extent. 3. The inhibitory effect of the all applied pesticides on_the_ nitrification under flooded condition was observed markedly and may be ordered as insecticides, herbicides and fungicides according to its inhibiting action.