• Korean journal of applied entomology
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• v.33 no.4
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• pp.207-215
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• 1994

The brown planthopper (BPH), Nilaparuata lugens, is the major pest 01 nce in Asla. Cument control tactics rely pnmalily on chemical ~nsecticides and resistant nce varieties In Korea, the most important biolog~cal conb-ol agent appears to be the naturally-occuning, mermlthid nematode, Agarnermrs unka. Although parasitism of BPH is highly variable from place to place and from year to year. the rnermithid is a promising biological control agent because it reduces the fecundity of the host and ultimately causes its death. The memithid has only one generation per year compared to the three to four generations of BPH, but the mermithid lemales stagger their egg production so that many individuals in all BPH generations are parastized. Augmentation of this rnermithld into BPH populations is only psslble on a limited scale because it is an obligate parasite and mass production technology has yet to be developed. Conservation of naturally-occumng populations through cultural techniques and the use of compatible resistant rice varieties and chemical insecticides may lead to an effective integrated pest management program for BPH.

• Research in Plant Disease
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• v.14 no.2
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• pp.85-89
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• 2008

Clubroot of Chinese cabbage, caused by Plasmodiophora brassicae, is one of the most serious plant diseases in the world. The objectives of this study were to investigate the effect of the irrigation times on the development of club root after planting and to evaluate the effect of clubroot disease on yield of chinese cabbage in pot and field. The clubroot disease gradually increased with increasing irrigation frequency after planting. The growth characters and yield of chinese cabbage by irrigation times varied according to soil moisture and clubroot disease severity. Based on marketable yield and control value, an ideal irrigation point was at the soil matric potential of 0.06 MPa. These results suggest that the suppression on clubroot disease development could be achieved by initially reduced irrigation times after planting. Future studies on irrigation times using fungicide treatment and resistant cultivar under natural field conditions are required to improve the control effect of clubroot.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.339-346
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• 2006

Total 90 species of medicinal plants were surveyed to see if they have any suppressive effects on the dinsity of M hapla at the exhibition field in the Chinan medicinal herbs experiment station. In 70 species including Achyranthes japonica, root-knot and/or egg sac of M. hapla was not found and these plants were planted in C. lanceolata field to check the degree of M. hapla infection. In 26 species including A. japonica, M. hapla infection was not observed. Simultaneously, 30 species were planted in pots to find out degree of infection by M. hapla. Dianthus chinensis, Rudbeckia bicolor, Sedum kantschaticum, Ricinus communis, Anemarrhena asphodeloides, Malva verticillate, Chelidonium majus, Sesamum indicum, Agrimonia pilosa, Geum aleppicum, Sanguisorba officinalis and Scrophularia buergeriana were free from infection. While the number of galls and density of M. hapla in soil were higher to high innoculation density, and the growth of C. lanceolata was rower.

• The Korean Journal of Mycology
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• v.24 no.4 s.79
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• pp.322-328
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• 1996

It is possible to cultivate Pleurotus ostreatus on the crush medium of Reynoutria sachalinensis. The crush of leaves and stems of Reynoutria sachalinensis with water (1:8 W/V) enhanced mycelial growth of P. ostreatus. That mycelial growth of P. ostreatus on the crush medium was accelerated three times as fast as that on malt extract agar (MEA), and mycelial compactness was denser than that of on MEA. The same result was obtained on mixture of saw dust and the crush of leaves and stems in test tube and bottle. The addition of rice bran and the crush to saw dust was best for mycelial growth. Regardless of pH (4.5, 6.5 and 8.5), P. ostreatus could suppress the growth.

• Korean Journal of Organic Agriculture
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• v.22 no.2
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• pp.347-357
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• 2014

This study was conducted to evaluate the control effect of sodium dichloroisocyanurate (NaDCC) for Venturia nashicola on Niitaka pear during flowering period. As a nontoxic disinfectant, sodium dichloroisocyanurate is widely used in the field of hygiene and disease prevention, medical treatment, aquiculture as well as plant protection. NaDCC was sprayed on the pear tree inoculated with conidia ($4.5{\times}10^5spores/mL$) of Venturia nashicola and as a result the incidence of pear scab was 23.8% in 750mg/L and 26.2% in 1,000mg/L compare to the 51.6% incidence in untreated tree. No damage in the pollen of pear flower was detected with NaDCC treatments in the full bloom period for six pear cultivar including Wonwhang. A NaDCC single treatment in the early bloom of Niitaka pear showed more than 98% of fertilization rate. Furthermore, there was no incidence of Venturia nashicola on Nitaka pear trees treated with NaDCC 4 times during their growth period.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.186-190
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• 1998

To establish weed control method in no-tilled and rice straw-covered wheat sown coincidentally with rice harvest using combine-attached drill seeder, several herbicides and their combination were tested for 2 years. Similar number of panicle to hand-weeding plot was secured at sprayed plot with Buta EC + Glyphosate SL mixture just after seeding. Water-foxtail(Alopeculus aequalis) and broadleaf weeds were controlled effectively by Buta EC + Glyphosate SL mixture, showing the control efficacy of 92 percent. In the 1st cropping year, weed species occurred was simple and water-foxtail predominated nearly half. However, weed species was diversified and water-foxtail predominated 83.5 percent in the 2nd cropping year. Wheat yield of Buta EC + Glyphosate SL plot showed no difference with hand-weeding plot. Dry weight of water-foxtail showed closer linear relationship with wheat yield reduction than that of broadleaf weed.

• Korean Journal of Environmental Agriculture
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• v.10 no.1
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• pp.21-25
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• 1991

The influence of phosphorus and nitrogen application on the uptake of radioactive strontium by Chinese cabbage and raddish was studied in pot experiments. The dry matter yield of Chinese cabbage and raddish increased with the application of phosphorus and nitrogen. High yield of raddish was obtained by the additions of nitrate while Chinese cabbage was obtained by the ammonium. The content of potassium in the vegetables was enhanced by the application of phosphorus. and the calcium content increased with the application of nitrogen. The content of $^{90}Sr$ was higher in the raddish than in the Chinese cabbage while the $^{90}Sr$ activity in the dry matter of vegetables decreased considerably with the application of phosphorus and nitrogen fertilizer. This indicates that the suppression of uptake was more effective with the application of nitrate than with ammonium.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.325-331
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• 2007

A series of experiments were performed to evaluate effects of lettuce seed treatment with low temperature and dry heat treatment (DHT) on bolting response in the case of spring cultivation. During spring production in greenhouse, bolting response of the plants produced from the treated seeds was faster in the order of low temperature treatment, control and DHT. Plant height was increased 5-10 cm higher by low temperature treatment, but plant growth of some cultivars was inhibited by DHT. Difference on lettuce plant growth between low temperature treatment and DHT was gradually diminished with the lapse of time after transplanting. Fresh weight of plant was not significantly different among all treatments. 'Red Gyeolku' showed very early bolting response and plant height was significantly promoted by low temperature treatment. However, 'Cheongchima' showed low bolting percentage after various seed treatments, so it is considered late-bolting cultivar.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.5
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• pp.542-550
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• 1996

An experiment with alfalfa (Medicago sativa L.) plants was designed to investigate the changes in non-structural carbohydrate (NSC) contents and the activities of amylolytic enzymes during a regrowth period following defoliation. Sampling from hydroponic grown-plants were carried out at intervals during 24 days of regrowth. Shoot regrowth was very slow during the first 10 days and root growth was depressed after defoliation. Defoliation induced a great decrease in both total sugar and starch contents in taproots during the first 10∼14 days. A major recovery of NSC occurred from day 15. Averaged over sampling dates, the activity of exo-amylase was about 400-fold higher than that of endo-amylase. Exo-amylase activity in defoliate plants slightly increased until day 6 (maximum level) and then decreased. Endo-amylase rapidly increased for the first 4 days after defoliation and slightly increased afterwards to a maximum on day 24. These results showed that increase in amylolytic enzyme activity in taproots coincided with the time of starch utilization during regrowth and that indicated it plays an important role in starch degradation.

• Horticultural Science & Technology
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• v.16 no.4
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• pp.508-510
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• 1998

This study was carried out to establish the in vitro culture system of potato germplasms for minimizing the occurrence of variation and maximizing the culture period. We used osmoticum such as sorbitol or mannitol with sucrose in the absence of plant growth regulators. The growth of potato germplasms in the medium containing osmoticum was increased when the growth temperature was lowered. After six months storage in low temperature, plant heights of tetraploid was somewhat higher than those of diploid with the exception of stn-16 and the difference due to media was not observed. But after twelve months storage, survival rates of plants cultured in LSM 1(sucrose and sorbitol) was higher than those of plants cultured in LSM 2(sucrose and mannitol). The survival rate of stn-16, diploid wild species, was approximately 75% and it was considerably high. In Atlantic, tetraploid cultivated variety, every individual was survived.