• Korean Journal of Environmental Agriculture
• /
• v.31 no.3
• /
• pp.248-254
• /
• 2012

BACKGROUND: In order to elucidate residual characteristics of difenoconazole and thiamethoxam by treatment to sweet persimmons for one year and to generate the data for the maximum residue limit (MRL) establishment for those pesticides in or on sweet persimmon. METHODS AND RESULTS: Systemic fungicide difenoconazole WP (10% a.i.) and systemic insecticide thiamethoxam WG (10% a.i.) were sprayed onto 12~25-years-old sweet persimmons according to its preharvest interval (PHI), respectively, and then fresh sweet persimmons were harvested at 0, 1, 3, 7, 14, 21 days after treatment from pesticide-sprayed plots at each 3 sites. The analytical methods were evaluated to limit of quantification, linearity, specificity, reproducibility and recoveries. The crop samples were extracted with acetone and performed dichloromethane partition process. The extracted samples of difenoconazole were analyzed by GC-ECD and the thiamethoxam extracted samples were analyzed by HPLC with good sensitivity and selectivity of the method. The average recoveries of difenoconazole ranged from 87.5 to 99.5% with the percentage of coefficient variation in the range 4.1~7.6% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg). And the average recoveries of thiamethoxam and clothianidin ranged from 88.8 to 98.9% and 83.2 to 96.6% with the percentage of coefficient variation in the range 3.6~5.0% and 3.8~9.4% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg), respectively. The residue amounts ranges of difenoconazole were 0.2~0.56 mg/kg and the residue amount was decreased below the MRL level, 1.0 mg/kg, after 1 day harvest. The residue amounts ranges of thiamethoxam were 0.08~0.28 mg/kg and the residue amount was decreased below the MRL level, 0.5 mg/kg, after 1 day harvest. And the residue amount of clothianidin was below then 0.03 mg/kg for only one test site of 14 and 28 day samples. CONCLUSION: As a result, the residual amounts of difenoconazole and thiamethoxam were not exceeded the MRL of established criteria for sweet persimmon. The biological half-lives of difenoconazole and thiamethoxam were 13.6, 19.4, 16.3 and 10.0, 15.3, 14.0 days at each three test sites, respectively.

• Korean Journal of Environmental Agriculture
• /
• v.25 no.3
• /
• pp.276-283
• /
• 2006

To evaluate the effectiveness of the foliar spray of calcium on "Baekdo" peach fruit, we carried out experiments in the orchards. The sprays were applied with $CaCl_2\;(Ca:\;400mg.kg^{-1})\;and\;CaCl_2$ with adjuvants (amino acid, $2g.kg^{-1}$; phytic acid, $2ml.kg^{-1}$ and wood vinegar, $2ml.kg^{-1}$) for four times from June 12 through July 4 at weekly intervals. The fruits and leaves were evaluated for Ca content, firmness and incidence of Brown rot caused by Monilinia fructicola at harvest To evaluate fruit quality included Ca content, firmness natural decay during the storage, the fruits were stored at room temperature for 14 days. The Ca content in leaf and fruit flesh at harvest was significantly increased (P=0.05) in $CaCl_2$ + amino acid treatment among $CaCl_2$ treatments. However, there was not significant Ca content in fruit peel. The firmness of flesh increased significantly (P=0.05) in $CaCl_2$ + amino acid treatment. The natural decay (Rhizopus stolonifers) during storage at the room temperature for 14 days, the fruit treated with $CaCl_2$ + wood vinegar exhibited lowest (P=0.05) incidence. Also, the firmness of the fruit during storage was firmer with treated $CaCl_2$ than untreated fruit. In the treatments of $CaCl_2$ + phytic acid and $CaCl_2$ + amino acid, it was possible to reduce incidence of Brown rot caused by M. fructicola most effectively in the field. In addition, inoculation with M. fructicola in fruits was also the most effective treatment for inhibiting disease development in vitro. These results suggested that the foliar spray of $CaCl_2$ with adjuvants increased the content of Ca and firmness of the fruits positively. It also inhibited the natural decay and the Brown rot effectively.

• Journal of Sericultural and Entomological Science
• /
• no.12
• /
• pp.37-45
• /
• 1970

The processing management forms of our country's filature factories in 1969 are summarized as follows. (1) About 80％ of total cocoon collection is made within 5 days involving peak day, and 10％ of cocoon collection is finished until 3 days before and after the peak day, (2) About 92％ of alive cocoons transported on unpaved road, and about 40％ of the cocoons purchased by all factories are loaded on trucks from common selling station which is far beyond 40km, therefore a new packing system of alive cocoons to drop the damage of cocoon qualities, should be taken. (3) 22％ of all factories in our. country have only low-temperature cocoon drying machine. Therefore the installment of hot-air cocoon drying machine is required urgently. (4) In view of cocoon qualities in our country, the grouping method of cocoon for reeling. taken by about 50％ of the factories at percent, which classify cocoons for reeling as high group (1,2,3,4 grades) and low group(5,6 grades), will have to be replaced by the method tat classify them high group (1,2 grades) middle group (3,4 grades), low group (5,6 grades). (5) The .ratio of cocoon assorting stood about 10％ in multi-ends reeling, about 15％ in automatic reeling, conclusively, the ratio of cocoon assorting for automatic reeling was higher tan that for multi-ends reeling. One person's ability for a day in cocoon assorting reaches to about 80-100kg. (6) Cocoon cooking condition requires the increase of the cooking time, the pressure and temperature used to be prolonged as much as the qualities of cocoons are material cocoon ior automatic and double cocoon machines are treated uncompletely. (7) Automatic silk reeling is being performed at 1-2$^{\circ}C$ lower in reeling water temperature and operated at about twice velocity. (8) The temperature and humidity of rereeling room stood at 25$^{\circ}C$, 67.2％ R.H and 32.3$^{\circ}C$, 51.9％ R.H of rereeling machine are showed, Average rereeling velocity is 233m/min and large reefs charged for one person are 7.5 reels and form of skein used in all factories is double skein. (9) About 73％ of water sources for filature used under-earth water. About 48％ of all filature factories in our country have not yet water purifying equipments. Installation of the equipment for these factories seems to be urgent, (10) Denier .balance, sizing reel, seriplane, are being used in most factories as self-inspection apparatus. (11) More than 90％ of the factories use the vacum tank in rereeling process and about 20％ of them use it in cocoon cooing process (12) Only 21％ of the factories use chemicals in filature process. About all them use "Seracol 100" in cocoon cooking process and "Seracol 500" in rereeling process, (13) Above survey results explain each all factories show large difference in the processing management. Therefore, it is believed that intercommunication through seminar or technical exchange will contribute to the production evaluation of cocoon in our filature industry.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.32 no.2
• /
• pp.201-207
• /
• 1987

This experiment was conducted to identify the superior corn hybrids for silage production and to determine the combining ability of their parental inbred lines. A 7-entry diallel cross was evaluated for grain and stover yields, and agronomic characters under 3 different seasons. Hybrids Hi34 x Tx601, Hi26 x Hi34, and Hi29 x Hi34 showed high total dry matter yields. In general, late maturing hybrids had higher grain and silage yields than early maturing hybrids. Leaf area index was correlated with grain and stover yields. Rust rating was negatively correlated with yields and all characters, indicating that rust (Puccinia sorghi) was one of the major factors affecting yields. Diallel analysis showed that inbred Hi34 which was late in maturity and resistant to rust was the best combiner for both grain and silage yields. General combining ability (GCA) and specific com-bining ability (SCA) effects for yields and other characters were significant, suggesting that both additive and non-additive gene effects are involved for those characters. Ratio of GCA/SCA mean squares showed that GCA effects were more important than SCA effects for yields and other characters. GCA x season and SCA x season interactions were significant for grain and stover yields, revealing that gene effects were not stable for those yields under dissimilar environments.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.10
• /
• pp.61-71
• /
• 1971

This study was conducted in order to investigate the effects of slaked lime and borax on the Akiochi paddy field. The pot trial(slaked lime was treated 0, 6, 10, 15g and borax 0, 0.75, 1.5g per pot) and the field trial(slaked lime was treated 0, 100, 200kg and borax 0, 10, 30, 50kg per 10are) respectively. The results are summarized as fo11ows. I. Pot Trial: 1. In a heavy treated of borax, appeared chlorosis on whole leaves(bottom) in early growing stage, However, in about 25 days after transplanting, these chlorosis were disappeared gradually. And in proportion to close by maturity after the ear-heading, changed to dark brown color and rolled at the end of upper leaves, finally withered. At the same time the part of the end of grains was also colored to dark brown. 2. Slaked lime effected to increase the ti1lering, hence increased the number of ear, on the other hand, borax showed the tendency of repression the tillering, conversely. 3. Borax effected to hurried up to heading date of rice plant, to which borax had been the plot of B$_1$ to 3 days and B$_2$ to 5 days, hurried up than control respectively, regardless of the quantities of slaked lime application. 4. According to the application of borax, the length of culm were shortened, otherwise the length of panicle were longished, then no recognized the. independent effect of slaked lime. 5. The number of grains per panicle were seemed like increased by treatment of slaked lime, but the grain were decreased in the heavy treatment of slaked lime and borax. These phenomena were showed in ratio of maturity likely tendency as above. 6. In the 1, 000 grains weight of brown rice, in the case of slaked lime was almost no significant, otherwise by increase the application of borax, increased the weight of 1, 000 grains and the size of the grains was greater. 7. The weight of rough rice and straw were showed the same tendency as the number of grains and maturity ratio. particularly, showed the phenomenon of the reduction by the heavy application of borax. II. Field trial: 1. In a heavy treated of borax, appeared chlorosis in a early growing stage, according to close by maturiting date after the ear-heading changed to dark brown the end of upper leaves, finally dried. 2. Slaked lime application accelerated the growth and increased the number of ear, but borax showed the tendency of repression the tillering. 3. Borax effected to hurried up to heading date of rice plant, according to heavy treatment of borax quickened heading date for 4 to 5 days. 4. As a whole, culm length was repressed by borax treatment. 5. Borax application 10kg per 10are advanced progress the maturity, but in the case of above 30kg per 10are of borax showed the tendency obstruction the maturity. 6. The yield of rough rice and brown rice recognized the independent effect of slaked lime and borax, respectively. the yield was decreased by the abundant of borax.

• Horticultural Science & Technology
• /
• v.34 no.1
• /
• pp.195-205
• /
• 2016

Sugar beet cyst nematode, Heterodera schachtii, causes serious economic losses worldwide in Brassicaceae crops. In 2011, this nematode was first found in highland vegetable cultivation areas in Korea, and thereafter spread to the surrounding healthy Chinese cabbage fields. However, little has been documented on the biological and ecological characteristics of the sugar beet nematode in highland vegetable cultivation areas. In this study the dispersal of the sugar beet cyst nematode was examined, focusing on spreading through soil and/or water infested with the nematode. When farmers with work boots trampled on Chinese cabbage fields for 10 minutes, the number of cysts recovered from the soil attached to the working differed depending on the research sites. Under irrigation conditions of 2, 4, and 8 liters of water per $m^2$, the amounts of soils attached on the bottom of the work boots and the number of healthy cysts in the soils increased significantly with the increase in soil moisture, although the total number of cysts, eggs, and juveniles did not increase significantly. After driving on the farm road adjacent to cabbage fields infested with the sugar beet cyst nematode, cysts were also recovered from the soil attached to the vehicle's tires, suggesting that the sugar beet cyst nematode can spread to new fields through soil carried by vehicles and by farmers. An excavator and a motor truck could deliver 41 kg and 224 g, respectively, of soil on the shovel shoes and the wheels to other locations during the Chinese cabbage harvest, suggesting that farming equipment and transportation vehicles may be vital means by which the cyst nematode spreads to non-infested fields in the highland area of Korea. Runoff water also contained cysts, whose amounts increased after water irrigation onto the ridges to simulate rainy conditions, with no significant difference in the number of cysts with increasing amounts of irrigation water. All of these results confirmed that the sugar beet cyst nematode spreads through soil attached to work boots, harvesting tools, and transportation vehicles, especially during the harvest time, and through runoff water on rainy days. These observations suggest that personal sanitization and cleaning of working tools and vehicles are one of the most important means to prevent the dispersal of the sugar beet cyst nematode in fields.

• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.2
• /
• pp.145-149
• /
• 1996

Depending on compost treatment the changes of radish morphology and soil physico-chemical properties were investigated in the sandy loam soil, pH of the soil was decreased and the contents of organic matter, total nitrogen, phosphate and cation exchange capacity was increased with increase of compost. Root weight and length were the lowest, but deficit rate was the highest(79.3%) in the treatment of 120Mg/ha of compost. The contents of chlorophyll and sugars were increased with increasing the amount of compost treatment, but the inorganics were scarcely changed. The nitrate content in radish root ranged from 10 to 120mg/kg in various treatments.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.2
• /
• pp.120-127
• /
• 2015

BACKGROUND: Supervised residue trials were conducted to establish pre-harvest residue limit(PHRL), a criterion to ensure the safety of the pesticide residue in the crop harvest, of amisulbrom for winter-grown cabbage in two fields. Following to application of amisulbrom on the crop, time-course study was carried out to obtain the amisulbrom dissipation of statistical significance which enabled to calculate the predicted values of PHRL. METHOD AND RESULTS: During cultivation under greenhouse condition, samples of winter-grown cabbage were collected at 0, 1, 3, 5, 7 and 10 days after amisulbrom application, and subjected to residue analysis. Analytical method was validated by recoveries ranging 93.7~100.0% as well as limit of quantitation(LOQ) of 0.04 mg/kg. Amisulbrom residues in winter-grown cabbage gradually decreased as time elapsed. The dissipation rate of the residue would be affected by intrinsic degradation along with dilution by the cabbage growth. The decay pattern was well fitted by the simple first-order kinetics. CONCLUSION: Biological half-lives of amisulbrom in winter-grown cabbage ranged 3.7~4.1 days in two field conditions. Based on the regression of amisulbrom dissipation, PHRLs of amisulbrom in winter-grown cabbage were recommended as 8.86~9.47 and 4.21~4.35 mg/kg for 10 and 5 days before harvest, respectively.

• Current Research on Agriculture and Life Sciences
• /
• v.1
• /
• pp.95-100
• /
• 1983

A soil hardness meter with strain gages was developed in order to measure the hardness of the soil. Soil hardness tests were conducted at the laboratory based on this measuring system. Also, these results were compard with that from the cone penetrometer which is widely used for this purpose. The following conclusions were drawn from the results. 1. Since the correlation coefficient of calibration curve obtained from the soil hardness meter with strain gages was 0.99876 and that of calibration curve obtained from the cone penetrometer with dial gage was 0.97150, the soil hardness meter with strain gages was more recomendable than that with dial gage for this purpose. 2. Standard deviations of soil hardness for sands and soil of paddy field when the soil hardness meter with strain gages was used were 6.794 and 8.271, respectively and that of soil hardness for sands and soil of paddy field when the cone penetrometer with dial gage was used were 7.490 and 9.169, respectively. Thus, the soil hardness meter with strain gages seemed to have lower measuring error than with dial gage.

• Korean Journal of Soil Science and Fertilizer
• /
• v.6 no.4
• /
• pp.213-219
• /
• 1973

Effects of three slow-release nitrogen fertilizers (Sulfur-coated urea, (SCU) Jin Hae Chemical Co. Korea(JHC); Tennessee Valley Authority. U.S.A(TVA); METAP, Japan) on the yield and nitrogen uptake of IR667 (Suwon 213) were investigated comparing with urea split application under the field condition with early and usual saeson cultivation. 1. SCU(JHC) was not superior than urea split application in yield and nitrogen nutrition due to early release of nitrogen. 2. SCU(TVA) outyielded urea split by 10% showed always highest nitrogen content in straw and most balanced relative cumulative curve of nitrogen uptake or dry matter yield. 3. At ear formation stage SCU(TVA) showed specially high nitrogen content which was highly correlated with number of grain per $m^2$ of field. 4. Only SCU(TVA) showed one peak curve of nitrogen uptake rate at ear formation stage while others showed two peak pattern. 5. nitrogen fertilizer recovery of slow-release fertilizers was higher than urea split in early season cultivation and SCU (TVA) (46.0) was higher but SCU(JHC) (38.9) was similar in compare with urea split(37.1) in usual season cultivation. 6. Most promising slow-release nitrogen to match plant requirement seems to be one mixed of various slow-release fertilizers having different release pattern.