• Research in Plant Disease
• /
• v.12 no.3
• /
• pp.231-234
• /
• 2006

The influences of powdery mildew caused by Sphaerotheca fusca were assessed on cucumber to verify the economic injury level and yield response. Based on the relation of disease severity and yield response, economic threshold was determined by grading the disease severity of powdery mildew. Yield loss simulation due to damage of powdery mildew was conducted by defoliation of lower cucumber leaves in two seasons. The minimum number of leaves was 10 in spring season and 13 in autumn season which made no distinct difference on cucumber yield. The whole yields of cucumber was reduced as the disease severity was increased. Therefore occurrence of powdery mildew have a negative effect on cucumber yield. The regression equation between disease severity and yield loss showed Y=-57.237x+6143.1, $R^2=0.9628$. This equation suggests the disease severity of economic threshold is 17.6%, which is 3% reduction point of yield based on yield and economic relations. These results suggest that application of fungicide should be needed when 1 or 2 leaves of cucumber are infected by powdery mildew in the growing season.

• Korean Journal of Medicinal Crop Science
• /
• v.16 no.1
• /
• pp.33-38
• /
• 2008

This study was carried out to reduce the number of chemical treatment by optimal apply for the disease and pest and obtain the basal data of environmental-friendly cultivation in Panax ginseng in 2006. The result by checking disease Incidence and pests fried in ginseng field of jeollabuk-Do was as follows. The kind of disease occurred in Jinan was 8 including Rhizoctonia solani, 7 with Botrytis cinerea in Jeongeup, and also 6 with Botrytis cinerea in Kochang within Jeollabuk-Do. It was required thorough disease control before the rainy season because the occurrence time was peaked around July. Also, the most serious disease in Jeollabuk-Do was Alternaria alternata, Botrytis cinerera, and Colletotrichum gloeosporioides. The actual harmful pests in ginseng field were Asusta despecta steboldiana and Holotrichia sp. and in other method using black light trap, Maladera orientalis, Ostrinia furnacalis, and Holotrichia morosa were mainly trapped.

• Korean journal of applied entomology
• /
• v.17 no.2 s.35
• /
• pp.81-87
• /
• 1978

Late blight incited by Phytophthora infestans (Mont.) de Bary, is an important problem for seed potato prodcution in Korea. At the alpine Daekwanryeong area, unprotected potatoes are often defoliated within 14 days after late blight is first observed in the field. Since regular spraying can control late blight, the forecasting service is needed for timely initiation of the spraying program. Climatological data and notes on late blight incidence were recorded during 1970-1977 at the Alpine Experiment Station. The moving graph method using 7-day average mean temperature and 7-day total rainfall did not give highly accurate forecasts. Adding data on relative humidity and 7-day average minimum temperature increased the usefulness of the moving graph. Yields of late blight susceptible varietieties in sprayed plots were related to late blight occurrence and to the rainfall distribution pattern.

• Korean journal of applied entomology
• /
• v.31 no.4
• /
• pp.551-559
• /
• 1992

These studies were conducted to investigate the biological effects of buprofezin 25% WP on the adult of the brown planthopper (BPH) and its control effects on the BPH population, when buprofezin was treated on different days after the introduction of the BPH adult to the potted rice. Also age structures of the BPH population at the time of buprofezin treatment were observed. The results were as follows: Buprofezin (7.0 g a.i./l0 a) could reduce the longevity and fecundity of the newly emerged female but did not affect the biology of older female, and it did not affect the biology of the male. The larval densities at the time of buprofezin treatment was reduced to nearly zero after treatment. The higher the residual effect and the proportion of larvae at the time of buprofezin treatment were, the higher its con¬trol effect on the BPH population was. In case of buprofezin 7.0 g a.i./l0a treatment, the time interval of treatment that could show the highest control effect was about 10 days (from 18 days after the adult introduction to the adult emergence days of next generation).

• Journal of Korean Medical classics
• /
• v.18 no.3 s.30
• /
• pp.106-115
• /
• 2005

${\ulcorner}$상한론(傷寒論)${\lrcorner}$시동한시기장기적저작(是東漢時期張機的著作), 시한의학제일부임상의학전저(是韓醫學第一部臨床醫學傳著), 저부서용리법방약어일로(這部書熔理法方藥於一爐), 개변증론치지선하(開辨證論治之先河), 시고대의학이론적존기지작(是古代醫學理論的尊基之作). ${\ulcorner}$상한론(傷寒論)${\lrcorner}$당중사용치자적처방유8종(當中使用梔子的處方有8種). 저사처방당중(這些處方當中), 치자시탕, 치자건강탕(梔子乾薑湯), 치자후박탕(梔子厚朴湯), 치자감초시탕, 치자생강시적하면도유일구' 득토자('得吐者) 지후복(止後服)'. 저개구자가해석위'(복용해탕후(服用該湯后))토자정지계속복용(吐者停止繼續服用)'. 거차가이인위사용치자적이상5개처방구유용토공능. 대우저개관점, 력대의가유사지긍정성태도(歷代醫家有些持肯定性態度), 유사인위시와전(有些認爲是訛傳), 지부정태도(持否定態度). 대차필자근거여하삼개방면, 즉(卽): 제일(第一), ${\ulcorner}$신농본초경(神農本草經)${\lrcorner}$화(和)${\ulcorner}$명의별록(名醫別錄)${\lrcorner}$당중미제도치자구유용토공능(當中未提到梔子具有涌吐功能). 제이(第二), 사용치자적기타삼개방제, 미제도(未提到)‘토(吐)’. 제삼(第三), 종제도저5개처방적조문내용래간, 시불능사용토법적(是不能使用吐法的). 인위(認爲)‘득토자(得吐者), 지후복(止後服)’ 시후인오첨적구자(是後人誤添的句子), 병차인위치자무용토공능(幷且認爲梔子無涌吐功能).

• Korean Journal of Weed Science
• /
• v.31 no.4
• /
• pp.401-404
• /
• 2011

Bromobutide, a paddy field herbicide, can effectively control annual and perennial weeds. It has an excellent weeding effect especially against Monochoria vaginalis and Scirpus juncoides etc. When it is mixed with other herbicides controlling weed spectrum and application timing can be broaden. Bromobutide has stable weeding effects regardless of field and weather conditions, and there is almost no phyototoxic effects to rice.

• Korean Journal of Weed Science
• /
• v.12 no.3
• /
• pp.271-291
• /
• 1992

This study was conducted to survey the situation of direct rice seeding in Honam province in Korea to investigate problems and seek countermeasure of weed control in direct rice seeding. The total area of direct rice seeding in the south-western part of Korea (Chonbuk, Chonnam, and Chungnam) was 1650.8ha (732.1ha for direct seeding in dry field and 918.7ha for direct seeding in flooding field) in 1992. The followings are summary of the study. 1. In case of direct rice seeding in dry field, butachlor EC and G at 3 to 5 DAS was mostly selected by farmers to control weeds in dry field. Benthiocarb or chlornitrofen was also used in few cases. At 10 to 14 DAS just before rice emergence, tank misture of butachlor EC and paraquat was treated by some farmers. At 35 to 40 days, after flooding mixture of sulfonylurea derivatives was sequentially applied. Surviving weeds including barnyardgrass were finally controlled by mixture of bentazon+quinclorac WP foliage application. 2. In case of direct rice seeding in flooding field, weed control were mostly unsuccessful partially due to wrong selection of herbicide and missing the optimum application time. Three relatively successful weed control in the survey were summarized as follows. 1) Oxadiazon EC, butachlor or benthiocarb were treated just after puddling(5 to 7 days before seeding). then mixture of bentazone+quinclorac WP or sulfonylurea derivatives was sequently applied to control remaining weeds at 20 days after seeding. 2) Mixtures of bensulfuronmethyl+dimepiperate G, pyrazosulfuronethyl+molinate G, or bensulfuronmethyl+mefenacet+dymron G were applied at 11 days after puddling when barnyardgrass were at 2.0 leaf stage. Phytotoxicity was not found in case of mixture of bensulfuronmethyl+dimepiperate G but found in the other two cases but disappeared later. 3) Mixtures of bensulfuronmethyl+quinclorac G., pyrazosulfuronethyl+quinclorac G or betazone and quinclorac G were treated after 18 to 20 days after puddling when barnyardgrass was within 3.0 leaf stage. It showed good weed control in both annuals and perrenials without phytotoxicity. On the contrary, other sulfonylurea derivatives such as middle periodic herbicide showed poor weed control against barnyardgrass, so that sequential treatment of bentazone+quinclorac WP mixture was required. 3. Herbicidal characteristics and optimum application time of 45 rigistered herbicides in Korea were analyzed to discover new substitute for quinclorac mixture, that showed excellent weed control against barnyardgrass at its 3 leaf stage or older. The analysis revealed that 70% of herbicides were for preemergence and the others were post periodic herbicide. Most farmers favor to apply herbicide when rice seedlings completely rooted, at this time barnyardgrass are at 2.5-3.0 leaf stage. Therefore herbicide of which optimum application time had long is required. In this study. 6 middle periodic herbicides among sulfonylurea derivatives and 2 quinclorac mixture were selected and evaluated their weeding spectrums at different leaf stage of barnyardgrass in both soil application in flooding condition and foliage application in dry paddy field. The order of weeding spectrum in magnitude was as follows : bentazone+quinclorac WP> bentazone + quinclorac G>bensulfuronmethyl + quinclorac G>pyrazosulfuronethyl + quinclorac G> pyrazosulfuronethyl + Molinate G>bensulfuronmethyl + mefenacet + dymron G>bensulfuronmethyl + mefenacet G>bensulfuron methyl+benthiocarb G. The above results coincided with that of the survey. In conclusion, there is no proper substitute for quinclorac mixrure, which can control barnyardgrass at 3.0 leaf stage or even older. Therefore quinclorac should be supplied continuously to farmers in order to anchor direct rice seeding in Korea. Author suggested the followings to eastablish direct rice seeding technology effectively and quickly : 1) A tentatively named "The research committee for direct rice seeding" which was composed of farmers. researchers and goberment. should be eastablished to cooperate effectively. 2) Development of a pricise direct rice seeding machine for both dry and flooding paddy field. which is workable regardless of condition and varieties of seeds. 3) Study on protecting rice seed and seedling from sparrows. 4) Systematic studies of weed control techniques in direct rice seeding to standardize herbicide application. 5) Studies on farm-land reformation. techniques of precise land preparation. and direct rice seeding using an airplane.

• Journal of Korean Society of Forest Science
• /
• v.89 no.5
• /
• pp.685-690
• /
• 2000

Caliroa carinata (Zombori) has heavily damaged the forests of Quercus mongolica in Sangju, Kyongbuk, Korea since 1996. However, information on the ecology and control of this pest was badly scarce. Thus we tried to study the ecology and chemical control of the sawfly through this study. Caliroa carinata is one generation per year. The adult sawflies emerged from June 8 to July 5 with peak at June 18. A female adult laid 11 eggs in rows on the backside of a leaf along the midribs and larger veins. Larvae have six instars, and the developmental period required to complete the larval stage was 19 days and 17 days at temperatures of $20^{\circ}C$ and $25^{\circ}C$, respectively. Each larval stage required 2-4 days to complete the development. The sawfly mostly preferred Quercus mongolica and Q. dentata, while avoiding Q. variabilis. Such insecticides as Tebufenozide, Flufenoxuron, Etofenprox, and Fenitrothion were sprayed on host plant leaves infected with test larvae in order to study the mortality. After 3 days of insecticide treatments, the mortalities were thoroughly examined. All insecticides showed higher than 95% of mortalities. Control values were also higher than 93%. The optimal season of insecticide application for pest control was estimated from late June to early July.

• Korean journal of applied entomology
• /
• v.27 no.4
• /
• pp.185-189
• /
• 1988

Laboratory trials were conducted for control of onion maggot and tobacco cutworm with ento¬mogenous nematodes. The onion maggot, Delia antiqua, was exposed to Steinernema feltiae at concentration of 0,30,60, 120 or 240 nematodes per larva, and to Heterorhabditis heliot-hidis at concentration of 0, 10, 20, 40 or 80 nematodes per larva. Mortalities of the maggot ranged from 80 to 100% in S. feltiae and from 63.3 to 100% in H. heliothidis. The tobacco cutworm, SpodoPtera litura was exposed to S. feltiae at concentration of 0,50,100,200 or 400 nematodes per larva and to H. heliothidis at concentration of 0,20,40,80 or 160 nemat¬odes per larva with or without kale in petri dish. The 3rd instar larvae of the tobacco cutworm was more susceptible to both nematode species than the 4th or 5th instar at low concentration. Mortalities of the 3rd instar were 100% in S. feltiae and 67.7-100% in H. heliothidis while those of 4th and 5th instar ranged 76.7-100% and 43.3-100% in S. feltiae, and 36.7-90% and 3.3-90% in H. heliothidis, respectively. Mortalities of the tobacco cutworm larvae decreased when the nematodes were sprayed on the kale leaves in petri dish except 3rd instar.

• Korean journal of applied entomology
• /
• v.48 no.2
• /
• pp.237-243
• /
• 2009

This study was conducted to develop economic injury level (ElL) and economic threshold (ET) of Cabbage armyworm, Mamestra brassicae L. on cabbage (Brassica oleracea L. var). The changes of cabbage biomass and M. brassicae density were investigated after introduction of larval M. brassicae (2nd instar) at different densities: 0, 1, 2, 4, 8, and 16 larvae per plant at 40 d after planting for an open field experiment, and 0, 2, 5, 8 and 12 larvae per plant at 25 d after planting for a glass house experiment. In the field experiment, the yield loss of cabbage was not significantly different among treated-plots at 30 d after the larval introduction, showing an over-compensatory response of cabbage plants to M. brassicae attack. In the glasshouse experiment, however, the biomass of cabbage at 15 d after the larval introduction significantly decreased with increasing the initial introduced number of M. brassicae, resulting in 38.3, 36.7, 21.7, 23.3 and 16.7g in above treated-plots, respectively. The relationship between cumulative insect days (CID) and yield loss (%) of cabbage was well described by a nonlinear logistic equation. Using the estimated equation, ElL of M. brassicae on cabbage was estimated at 44 CID per plant based on the yield loss 14%, which take into account of an empirical gain threshold 5% and marketable rate 91% of cabbage. Also, ET was calculated at 80% of the EIL: 35 CID per plant. Until a more elaborate EIL-model is developed, the present result may be useful for M. brassicae management at early growth stage of cabbage.