• Journal of Life Science
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• v.9 no.2
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• pp.121-126
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• 1999

Some attempts were made to investigate the honeydew excretion of the brown planthopper(BPH), Nilaparvata lugens Stal, biotypes in terms of instal nymph, days after emergence, macropterous and brachypterous mated and unmated female, and macropterous female with different sources fed on 60-day-old rice cultivars with different resistance genes. The feeding amount of the BPH biotypes was measured by using the honeydew excretion test. The feeding amount of fifth instar on Miryang 23 with no resistance gene was higher than that of Cheon-gcheongbyeo with Bph-1 gene by two times. Macropterous and brachypterous females showed low feeding amount at first day after emergence, but they showed high feeding amount from second days after emergence. Also the feeding amount of brachypterous female was higher than that of macropterous female. In addition, the feeding amount of BPH was in the order of nymph

• Korean journal of applied entomology
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• v.43 no.2
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• pp.103-109
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• 2004

Seasonal occurrence of Japanese gall-forming thrips, Ponticulothrips diospyrosi Haga et Okajima, and its damage pattern on leaves and fruits were studied at sweet persimmon orchards in Gimhae (orchard A, B) and Changwon, Gyeongnam. Korea in 2002 and 2003. Monitoring adults by yellow sticky traps and inspecting each developmental stage in damaged rolled-leaves revealed that the overwintered adults moved to sweet persimmon orchard from late April to late May, and oviposited inside the rolled leaves. Adults developed from the eggs showed peak occurrence of the first generation adults in early to mid June. Inspection of rolled leaves indicated that the peak occurrences of eggs, nymphs, and pupae of the first generation took place in early to mid May, late May to early June, and early June, respectively. Each developmental stage showed the second small peaks in the late season. Results suggest that most thrips live a single generation per year, but a small portion may develop to the second generation in persimmon orchards. The percent of damaged leaves was highest in Changwon orchard at 9.7％ in early June. Percentage of damaged fruits increased from 0.84％ in early June to 30.2％ in early September in Gimhae B orchard. It was found that the closer the persimmon trees were to the edge of the orchard, the worse damaged the leaves were. Appropriate timing for incorporation of control measures were discussed in relation to the seasonal occurrence of adults.

• Research in Plant Disease
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• v.8 no.3
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• pp.179-183
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• 2002

to investigate occurrence of kiwifruit bacterial canker disease,172 kiwifmit orchards in Jeonnam and Gyeong-nam provinces were surveyed from March to April in 1999. In the south coast region of Korea, such as Haenam, Wando, Jindo, Jangheung, and Bosuns, red-rusty brown bacterial oozes were observed in 17 kiwifvuit orchards. Disease incidences varied from 2.2% to 100% depending on various regions. Total 22.8 ha of kiwifruit orchards were destroyed by occurrence backerial canker at 1999 in Korea. Orchard in Wando, Jindo, and Goheng were severely damaged in 1999. The seasonal variation of bacterial canker incidence was also investigated from 1996 to 1997 on leaves, vines and twigs of kiwifruit. Red-rusty brown bacterial ooze was exuded from mid February or early March to late April in creaked site of vine and twig. The seasonal incidence of bacterial canker on leaves appeared from late April to late June, and rapidly increased during May, Optimum growth temperature of Pseudomonas sytingae pv. actinidiae was at $25^{\circ}C$ on King's B medium and did not grow at 33$^{\circ}C$. We suggest that spreading of bacterial canker was suppressed under the plastic flim and windbreak net house.

• Korean journal of applied entomology
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• v.40 no.1
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• pp.59-67
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• 2001

The potential of two entomopathogenic nematodes, Sreinernema carpocapsae Pocheon strain and Heterorhabditis bacteriophora Hamyang strain as biological control agents was evaluated against mushroom ny, Lycoriella mali in laboratory and field. Mortality of L. mali was significantly different according to nematode species, concentration, temperature, and developmental stage of fly S. carpocapsae was more effective than H. bacteriophora. Mortality of L. mali was higher at $25^{\circ}C$ than at $20^{\circ}C$. In addition, the 3rd instal and the 4th instar of L. mali were more susceptible than the 2nd instar. The lowest $LC^{50}$ value was represented by S. carpocapsae, 20.0 infective juveniles (Ijs) in the 3rd instar, 27.5 Ijs in the 4th instar at $25^{\circ}C$. S. carpocapsae infected all the developmental stages of L. mali except egg stage and the 1st instar of larva. The highest mortality was shown in adult female representing 74.0% at$20^{\circ}C$ and 80.0% at $25^{\circ}C$.L. mali female adult was influenced by S. carpocapsae in oviposition. The number of eggs by L. mali female infected by nematodes was much lower than uninfected females. S. carpocapsae was dispersed by infected L. mali adult with higher numbers by females than males. When S. carpocapsae was applied at the rate of $2.25{\times}10^{5}\;and\;4.5{\times}10^{5}\;Ijs/1.5\;\textrm{m}^2$ in the mushroom house, mortalities were 42.2% and 81.6%, respectively. The infective juveniles of nematodes survived for 14 days in the mushroom medium. However, nematodes did not affect mushroom growth.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.11-18
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• 1984

The effect of transplanting method of rice seedlings on weed occurrence was investigated at the Yeongnam Crop Experiment Station in 1983. Rice was transplanted by hand and machine and eleven common herbicides were applied. The greatest weeds were harvested from the plot that rice was not transplanted and more weeds encountered at machine transplanted plot than hand transplanted plot. The degree of weed suppression by rice plant itself was 50% for machine transplatning and 55% for hand transplanting, respectively. Simpson index and community dominance of weed species were the highest in hand transplanting and followed by machine transplanting and no rice plot in order. Rice grain yield was exponentially correlated with the amounts of weed occurrence and more yield loss exhibited at machine transplanting than hand transplanting in the same amount of weeds. In the herbicidal activity, most of herbicides performed better at hand transplanting than machine transplanting while the degree of difference between transplanting methods varied depend on herbicide used.

• Korean Journal of Medicinal Crop Science
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• v.6 no.1
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• pp.44-50
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• 1998

The experiment was carried out to investigate weed occurrence in peony field. The number of weeds was Compositate 9 species, Gramineae 4 species, Craciferae 3 species, Eugarviaceae, Polygonaceae and Scrophularilaceae 2 species, respectively. Weeds classified by life cycle were annual weed 19 species (57.6%), biennial weed 8 species (24.2%), and perennial weed 6 species (18.2%). Weed species and dominance rate by morphological characteristics were grass weed 4 species (12.1%), broad leaf weed 25 species (84.8%), and sedge weed 1 species (3.1 %) . Major dominant weeds were Capsella bursa-pastoris, Chemopodium album var. centrorubrum and Equisetum arvense in late April, and Digitaria sanguinalis, Erigeron canadensis and Echinochlor crus-galli in late June, and Digitaria sanguinalis, Erigeron canadensis and Echinochlor crus-galli in middle August.

• Korean journal of applied entomology
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• v.16 no.2 s.31
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• pp.79-86
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• 1977

Four experiments were carried out under farmer's field conditions to determine economic threshold levels of major rice pests aad attempt a reduction in the number of insecticide applications. In the experiments were included check treatments, insecticide schedules representing the official recommendations to farmers, and several corrective treatments. A careful record was kept of insect pest densities and disease incidence. i) In the north at Suweon and Icheon where Chilo suppresalis. (Walk.), the striped rice borer, was active in the first generation, no significant yield differences were obtained between plots receiving several insecticide applications and those left totally unprotected. The mean yields were high (5.2-7.6t/ha). ii) First generation borer activity rising to $8.6\%$ injured tillers was below the economic threshold since no yield reduction was recorded in either japonica varieties or the high-yielding Tongil variety. iii) Evidence was obtained thst berer damage was made good by replacement of infested tillers (compensatory growth), C. suppressalis populations were always low in the second generation. iv) The experimental results obtained at Suweon and Icheon do not justify the present official recommendations of 6-7 pesticide applications. v) further south at Iri a substantial yield reduction occurred due to an early outbreak of stripe disease transmitted by Laodelphax striatellus (Fallen), the small brown planthopper; a mean of 1-2 individuals/hill was recorded immediately after transplanting. C. suppressalis probably contributed to this yield reduction. vi) Several applications against the vector failed to prevent the rapid spread of stripe to the susceptible variety in the Iri experiment: in surrounding fields the resistant Tonsil varivety was ralatively unaffected. vii) Pests of lesser importance were Nephotettix cinctieps (Uhler), Nilaparvata lugens (Stil), Sogatella furcifera (Horv..), and leaf miners.

• Korean journal of applied entomology
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• v.47 no.1
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• pp.51-57
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• 2008

This study demonstrates a variability in efficacy of mating disruption against the oriental fruit moth, Grapholita molesta, populations infesting apples cultivated in differential environmental conditions. Throughout the growing seasons, trap catches of G. molesta male moths and damaged leaf and fruit were examined to evaluate the efficacy of a commercialized mating disruptor. Treatment of the mating disruptor significantly reduced the trap catches of male moth in treated plot, compared to those of the untreated plot. This reduced trap catches were significantly correlated with leaf and fruit damage. Moreover, the highest host damage occurred in June just after the highest overwintering adult peaks in both plots. The treatment of mating disruptors in Chungsong effectively disrupted the overwintering population in April and May, resulting in no noticeable host damage during the following growing seasons. However, there was a marked difference in host damage between two plots, especially in late seasons. Variation in the efficacy of mating disruption technology in terms of host damage appeared to be related with nearby pheromone-untreated orchards, which may result in the immigration of gravid females.

• Research in Plant Disease
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• v.13 no.3
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• pp.152-156
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• 2007

Incidences of leaf blight of lily cultivars Raizan and Casa Blanca in the open field cultivation were 50% and 45.4%, respectively, while those in the green house cultivation were significantly reduced to 1.5% and 1.9%, respectively, In the green house, the incidences of the disease in sprinkler watering cultivation were $14.5{\sim}16.5%$, while those in drip watering cultivation were only $1.5{\sim}2%$. Incidence of the disease was severe in the field where the lily was cultivated successively for 2 to 3 years. Isolation frequencies of B. elliptica from overwintered plant debrises such as leaves, stems, capsules, and bulbs were 43.3%, 46.7%, 60% and 0%, respectively, while those of B. cinerea were 10.3%, 0%, 3.3% and 0%, respectively, Incidence of leaf blight in the field where diseased plant debris was cleaned was 7.3%, while that in the field where diseased plant debris was not cleaned was 56.5%. Incidences of the disease in the field where coverages of soil surface with black vinyl, bark or rice straw were used were 6.6%, 8.2% and 11.3%, respectively, while that in the field where the coverage was not used was 21.3%.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.387-394
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• 2013

The Rhizoctonia blight causing by Rhizoctonia spp. is an important disease of turfgrass, requiring fungicide application to maintain acceptable conditions for turfgrass good qualities in the golf course. The experiment was conducted to determine the mean 50% effective concentration inhibiting mycelial growth ($EC_{50}$) value of to flutolanil, pyraclostrobine and hexaconazole to Rhizoctonia solani AG-1 IB, Rhizoctonia cerealis and Rhizoctonia solani AG2-2IV isolated from Gyeongbuk province of Korea in vitro. Five discriminatory concentrations of each fungicide were used to detect in vitro sensitivity. The mean of $EC_{50}$ values to three systemic fungicides was the lowest isolate of R. solani AG-1 IB. However, the sensitivity of fungicides to Rhizoctonia solani AG2-2IV were higher mean $EC_{50}$ value of 0.026 ${\mu}g\;a.i.\;ml^{-1}$ of pyraclostrobine and 0.044 ${\mu}g\;a.i.\;ml^{-1}$ of flutolanil. R. cerealis was the lowest sensitivity to hexaconazole which was an average $EC_{50}$ value of 0.022 ${\mu}g\;a.i.\;ml^{-1}$. Inhibition of mycelial growth rate (%) by three combine fungicides using the $EC_{50}$ value of each fungicide was the highest R. solani AG2-2IV. Results of this study were may confirmed in vitro response fungicide of three Rhizoctonia species for control of Rhizoctonia blight in the field.