• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.312-316
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• 2015

Anthracnose, caused by Colletotrichum spp. is the most important and devastating disease in sweet persimmon production in worldwide. There is no alternative control method or resistant cultivar is available. Therefore, chemical controls are widely accepted to control the disease. Three fungicides among 16 fungicides have been selected to apply in field condition. The selected three fungicides (metconazole, dithianon and propineb) showed lower EC50 and reliable control effect in both in vitro and in vivo. According to general guide line of anthracnose disease control method recommended 8 times spay of the fungicide. In this study, we performed 8, 4, and 2 times spay of the fungicides. For 8 times application, practice spray machine has been used and for 4 and 2 time application, a recently invented spray machine was input. The fungicides have been treated from middle of June to end of August in 2014 year. Control effect of among the selected fungicides showed similar result regardless of sort of the fungicide. However, frequency of spray result showed significantly different results, 8 and 4 times fungicide application showed low and similar disease occurrence, but 2 times application showed intermediated disease occurrence between 4 times treatment and untreated control. Taken together, result showed that 4 times application with effective fungicide, mechanically advanced tool can reduced the anthracnose disease damage in sweet persimmon production.

• Research in Plant Disease
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• v.20 no.1
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• pp.8-14
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• 2014

The socio-network activities for regional governments, agricultural research institutes, developing agencies and policy makers of any countries are very crucial and important to take into account the root cause of current problems faced by farmers. The survey was conducted in South Korea during the period January, 2008 to August, 2012 in order to shed light on prevalence of different diseases on watermelon in different regions and to better understand farmers' knowledge and perceptions for following watemelon's growing procedures and practices. A total of 590 cases were reported on 573 watermelon growers with highest 87.1% in Jeonbuk, 4.7% in Jeonnam, and 8.2% in other regions such as Gyeongbuk, Gyeongnam, Chungnam, Gwangju, Gyeonggi, Daegu, Gangwon, Changwon and Seoul. The maximum percentages of cases recorded were related to diseases and insect pest (38.6%) followed by physiological disorder (29.7%), cultural practices (18.8%), soil and fertilizer (9.0%), herbicide (2.9%) and others (1.0%). It was observed that the manifestation aspects of the diseases were changed due to increasing in proportion of 'in-facility' cultivation to 12,995 ha compared to 'open-field' cultivation (2,722 ha). The present survey revealed the necessity to reduce the damages incurred at watermelon farms as soon as possible through the breeding program to develop resistant cultivar, use of pathogen-free propagating plants, and efficient prevention of pathogen by regular monitoring of watermelon plants at farms.

• Korean Journal of Plant Resources
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• v.14 no.2
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• pp.163-168
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• 2001

This study was conducted to obtain basic information on cross breeding for developing bolting resistant variety of Angelica gigas NAKAI which has been subjected to severe yield reduction resulted from flower-stalk initiation during the growth. Compatibility of selfing and/or crossing pollination among 5 local cultivars were tested. Results obtained are summarized as follows. In case of three year old plant, all cultivars emerged March 14 and bolted from May 12 to May 13. Ponghwa cultivar was flowered 3 to 5 days earlier than other cultivars. Flower duration continued 41 to 43 days. Interval of flowering date from main stem to first primary branch, from first to second or second to third primary branch was 9 to 13 days. Emergency of stamen proceeded 4~8 days of pistil initiation demonstrating that Angelica gigas NAKAI is protandrous plant. Furthermore initiation of first pistil was 1~4days later than formation of last stamen in the same flower cluster. Percent pollination of Angelica gigas NAKAI was 52% under natural condition, so called open-pollination, but bagging by enveloping flowers was as low as 0.4~2.4%. In the result of compatibility test, all local cultivars tend to show both of self-and cross-compatibility. Inpollination, ‘Muju’$\times$‘Muju’combination showed highest fertility up to 40.8% whereases cross pollination, ‘Pyeongchang’$\times$‘Inje’combination, showed 67.0% fertility.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.4
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• pp.258-263
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• 1991

There are ten NLCF's recommended sorghum-sudangrass hybrids(Sorghum bicolor (L.) Moench), but they have not been evaluated under same environmental conditions. Therefore, a field experiment was conducted to campare forage yield and quality of the NLCF's recommended cultivars of sorghum-sudangrass hybrids at the experimental forage field, College of Agriculture, SNU, Suweon over two years. Among the ten cultivars used, G83F and NC+855 were classified as early maturing cultivars. Pioneer 988 and Sordan 79 were more resistant to leaf blight than the other hybrids. Jumbo, Sordan 79 and SX-17 were susceptible to lodging. No significant differences in dry matter yield were found among the cultivars used, but the dry matter yields of Pioneer 988, TE-Haygrazer and G83F were slightly higher than the other hybrids in 1989 and those of NC+855 and Pioneer 988 were higher in 1990. There were no marked cultivar differences in CP, ADF, NDF and RFV at the first, second and third cuts in 1990, but the ADF, NDF and RFV of sorghum-sudangrass hybrids at the third cut showed more higher than those of the first and second cut forage. In conclusion, there are no forage yield differences among the ten NLCF's recommended sorghum-sudangrass hybrids.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.4
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• pp.268-274
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• 1990

In order to understand the effect of irrigation constraint on the growth and yield of the rice plant. two rice cultivars. Samnambyeo and Chucheongbyeo. were cultured in the pot controlled with different water levels: + 2 cm-submergence, and -17cm, -37cm, -57cm, -77cm, -97cm, -120cm, and -145cm depth from soil surface. 1. Among differently irrigated conditions, submerged condition was the best in growth and yield of both Samnambyeo and Chucheongbyeo. Yield and growth of rice decreased linearly with lowering the water level in sequence. 2. Samnambyeo appeared to be more drought resistant cultivar than Chucheongbyeo. It was regarded that physiologically critical water level on rice yield was about 70cm depth in Samnambyeo and 50cm depth in Chucheongbyeo. 3. The earliest heading date of the rice plant was from submergence condition and the head ing date was linearly delayed with lowering water level in sequence. The heading date of Samnambyeo was about 10days earlier than that of Chucheongbyeo at the same water level.

• Journal of Plant Biotechnology
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• v.35 no.1
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• pp.69-74
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• 2008

This study aims to establish the efficient soybean transformation system and develop soybean [Glycine max (L.) Merill] transformants using cotyledonary node explants. The cotyledonary node of soybean were co-cultivated with Agrobacterium tumefaciens strains (KYRT1, EHA105). These strains contain the binary vector pCAMBIA3301 which carries a herbicide-resistant far gene. Korean cultivars (Danbaekkong, Eunhakong) and foreign cultivars (Jack, Peking) were the most efficient in regenerating cotyledonary node. Therefore, they were chosen for the transformation. Results showed that the T-DNA transfer reached up to 60% and transformation efficiency reached up to 3% in the cotyledonary node explants from Jack cultivar, co-cultivated with EHA105 strain. Histochemical GUS evaluation showed that 12 individual lines, transformed with the 현 gene, have positive response. The transformed soybeans have been confirmed in the $T_0$ generation through phenotypic assay using herbicide $Basta^{(R)}$ and Southern blot analysis.

• Research in Plant Disease
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• v.19 no.2
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• pp.84-89
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• 2013

The incidence factors of Rice stripe virus (RSV) were analyzed by studying the population density and the viruliferous insect rate (VIR) of small brown planthopper (SBPH), the incidence of stripe disease, alternate host, and susceptible cultivar in Chungnam Province. The population of overwintering SBPH had been decreasing, but the VIR of overwintering SBPH had not been differing for three years, 2008 to 2010. No RSV was detected in the natural host plants, such as short awn, annual bluegrass, and barley. In 2009, relatively large population of SBPH with the VIR of 5.4% migrated from China. However, there was no evidence relating of migration large amount of SBPH from China in 2008 and 2010. Also the infection rate of RSV in rice was less than 1% in these periods. The cultivation area of the susceptible varieties had steadily decreased from 41% to 19% from 2007 to 2009. Therefore, the reduction factors of rice stripe disease in Chungnam Province with higher influx of inoculum could be with an appropriate forecasting and chemical control, cultivation of resistant varieties, changes in the cropping system, and the low winter-spring temperature.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.295-299
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• 2007

Resistance to chestnut gall wasp (Dryocosmus kuriphilus) of Korean prevailing chestnut cultivars, new cultivars released by Korea Forest Research Institute (KFRI), and local cultivars by growers was investigated to select optimal cultivars suitable for main chestnut producing areas. During three years investigated from 2004 to 2006, we could find no damage by chestnut gall wasp in any cultivars of test sites located in Gongju and Chungju of the central area. However, most cultivars of Gwangyang, Sancheong and Hapcheon sites located in the southern area showed a lot of damage by chestnut gall wasp. Hapcheon was most severe in comparison with regional damage by chestnut gall wasp. From comparison among cultivars, Kwangeun, Sandae, Eunsan and Idae released by KFRI showed no damage suggesting the highest resistant cultivars. On the contrary, over 20% in total damage by chestnut gall wasp was investigated in Tanzawa, Riheiguri, Kurakata-amaguri, Pyeonggi, Gwangdeok, Seil, Sinipyeong and Yumabyuni suggesting susceptible cultivars. In damage by chestnut gall wasp according to investigated position within tree, weak shoot was more severe than bearing shoot. Damage by chestnut gall wasp of major cultivars in Gwangyang, Sancheong and Hapcheon sites was remarkably decreased in 2006, and it seems to be caused by biological control by natural enemies such as Torymus sinensis.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.116-122
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• 2013

We investigated characteristics and self-incompatibility genotypes of 11 crabapple cultivars to introduce a new pollinizer of 'Fuji' apple tree in Korea. Flowering dates of eleven crabapples were two to seven days earlier than that of 'Fuji'. The rate of pollen germination in vitro was ranged from 85.6% to 98.0% except 'Virginia'. Controlled pollination treatment with each crabapples to 'Fuji' increased fruit set rate about 20.4% to 34.4%, the number of seed per fruit about 13.8% to 42.3% and fruit weight about 7.4% to 16.7% compared to open pollination. Tested crabapples were resistant to peach fruit moth, brown leaf spot and sooty blotch in general. A PCR amplification method using S-RNase primers was carry out in eleven crabapples. S-alleles, $S_3$, $S_5$, $S_9$, $S_{10}$, $S_{20}$, $S_{26} from six crabapples were determinated. Through sequencing analysis, $S_5$ ('Manchurian', 'Virginia') and $S_9$ ('Yantaishagou') showed 100% homologous to previous result. Based on our results, it was recommended that 'Manchurian', 'Hopa A', 'Hanyaehanakaidou', 'Spectabilis' could be promising pollinzers for 'Fuji' apple cultivar.

• Journal of Life Science
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• v.18 no.12
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• pp.1771-1774
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• 2008

Control microbial contamination in pathogens to soy sprouts has always been highly concerned in soybean sprout industries because the soybean sprouts are consumed largely as a nutritious fresh vegetable around the world. However, pathogens in soy sprouts are little known. Here, we isolated a strain of Pseudomonas sp. SN239 that caused severer symptoms in sprouts of many soybean cultivars. In phylogenetic relationships using 16S ribosomal RNA sequences of the Pseudomonas species, the identified Pseudomonas sp. SN239 was grouped with P. putita, P. plecoglossicida, P. monteilii and P. mevalonii. Thus, the bacterial strain SN239 might be a newly identified Pseudomonas species which closely related to P. putida. Furthermore, we found that a Korean indigenous soybean (Glycine max) cultivar YNPCSS3-19 has strong resistance against the Pseudomonas sp. SN239.