• Research in Plant Disease
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• v.13 no.3
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• pp.145-151
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• 2007

Xanthomonas axonopodis pv. glycines is the causal agent of bacterial pustule of soybean(Glycine max. (L.) Merr), which is one of the most prevalent bacterial diseases in Korea. In this study, Polymerase Chain Reaction (PCR) assay was applied to detect Xanthomonas axonopodis pv. glycines and to survey on seed contamination in 36 soybean cultivars of Korea. And we have to compare PCR assay with dilution-plating assay of detection and identification. We confirmed detection of pathogen from artificial infected seeds and natural Infected seeds using PCR assay. This assay gave results similar to a seed-wash dilution plating assay and proved more effective than classical methods. Results of survey on seed contamination by X. axonopodis pv. glycines from 36 cultivar seeds showed that the pathogen was detected from Pungsan-namulkong, Mallikong, Taekwangkong, Daemangkong, Ajukkarikong using PCR assay. Therefore, The PCR assay provides a sensitive, rapid tool for the specific detection of X. axonopodis pv. glycines in soybean seeds.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.58-64
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• 2015

The black cutworm, Agrotis ipsilon (Hufnagel) is a major insect pest of economic crops including turfgrasses on golf courses. The entomopathogenic nematode, Steinernema carpocapsae GSN1 strain (ScG), a Korean isolate, is an effective biological control agent for soil dwelling and greenhouse insect pests in Korea. In addition, ScG is commercially produced in Korea. We conducted laboratory, greenhouse, and field trials to evaluate efficacy of ScG against black cutworms in turfgrasses. A rate of 63 infective juveniles (Ijs) per larva killed >90% of $3^{rd}$ instars feeding in cups of artificial diet within 3 days. In greenhouse trials against cutworms feeding in pots of turfgrass, efficacy of ScG was higher against $4^{th}$ instars than against $2^{nd}$ instars (90.0 vs 81.2% mortality, respectively, at $2,000Ijs\;pot^{-1}$) in perennial ryegrass, and higher against $3^{rd}$ instars in creeping bentgrass, Agrostis palustris than in zoysiagrass, Zoysia japonica (96.7 vs 52.5% mortality at $100,000Ijs\;m^{-2}$) in pot. The corrected mortality of $4^{th}$ instar was 79.9% at the rate of $100,000Ijs\;m^{-2}$ in the creeping bentgrass in the field. So ScG could be used as biological control agent against black cutworm in turfgrass of golf courses.

• Journal of Life Science
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• v.26 no.11
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• pp.1336-1340
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• 2016

Korean rhinoceros beetles (Allomyrina dichotoma), which can be found in broad-leaved forests in mountainous habitats and lives for around one year in wild. This beetle is currently popular as a pet and traditionally regarded as a medicine for liver-related diseases in Korea. It is reported that the economic losses in the mass-rearing facilities by virus infection have been increased since the 2010s in Korea. The causing virus for the A. dichotoma was firstly reported as an Oryctes rhinoceros nudivirus (OrNV) in 2015. We, here, observes that serious morphological changes in the intestinal tube from the OrNV-infected beetles, and report five genes, which are regulated by OrNV infection in the intestine; Krueppel-like factor 15 (Klf15), Endoplasmic reticulum aminopeptidase 2 (ERAP2), U5 small nuclear ribonucleoprotein 200 kDa helicase (Snrnp200), Muscleblind-like protein 2a (mbnl2a), and MIMI_L93. The results may provide a clue to the early diagnosis and disease treatment during the mass-rearing facilities of the A. dichotoma.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.62-69
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• 2013

The black cutworm, Agrotis ipsilon (Hufnagel), damages various cultivated crops and it can also be a serious pest of turfgrass, especially on golf courses. Essential oils have potential as alternative control agents for insect pests. Sixteen essential oils (anise, camphor, cinnamon, citronella, clove, fennel, geranium, lavender, lemongrass, linseed, neem, peppermint, pine, thyme, turpentine and tea saponin) and paraffin oil were assessed in the laboratory, the green house and field trials for their efficacy against black cutworms in turf. Treatment of potted cores of perennial ryegrass turf with anise, cinnamon, neem, paraffin or turpentine reduced black cutworm damage in a greenhouse trial, and in a similar trial, applying neem oil at 4000, 2000 and 1000 ppm resulted in 100, 100 and 64% mortality, respectively, of black cutworms. Weight of survivors at the 1000 ppm rate was 5- fold less than weight of comparably-aged controls. Neem oil (2000 ppm) reduced growth of black cutworms feeding on treated clippings. A high rate of neem oil followed by irrigation (0.1 L of 20000 ppm neem oil with 0.9 L watering/$m^2$) was more effective than a lower concentration (1 L of 2000 ppm neem oil/$m^2$) against $2^{nd}$ and $3^{rd}$ instars in potted turf cores and field plots, respectively. However, not even the aforementioned higher rate effectively controlled $4^{th}$ instars in the field.

• Korean journal of applied entomology
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• v.12 no.3
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• pp.93-107
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• 1973

Garlic (Allium sativum L.) is an important vegetable crop for the Korean people and has long been cultivated extensively in Korea. More recently it has gained importance as a source of certain pharmaceuticals. This additional use has also contributed to the increasing demand for Korean garlic. Garlic has been propagated vegetatively for a long time without control measures against virus diseases. As a result it is presumed that most of the garlic varieties in Korea may have degenerated. The production of virus-free plants offers the most feasible way to control the virus diseases of garlic. However, little is known about garlic viruses both domestically and in foreign countries. More basic information regarding garlic viruses is needed before a sound approach to the control of these diseases can be developed. Currently garlic mosaic disease is most prevalent in plantings throughout Korea and is considered to be the most important disease of garlic in Korea. Because of this importance, studies were initiated to isolate and characterize the garlic mosaic virus. Symptom expression in test plants, physical properties, purification, serological reaction and morphological characteristics of the garlic mosaic virus were determined. Results of these studies are summarized as follows. 1. Surveys made throughout the important garlic growing areas in Korea during 1970-1972 revealed that most of the garlic plants were heavily infected with mosaic disease. 2. A strain of garlic mosaic virus was obtained from infected garlic leaves and transmitted mechanically to Chenopodium amaranticolor by single lesion isolation technique. 3. The symptom expression of this garlic mosaic virus isolate was examined on 26 species of test plants. Among these, Chenopodium amaranticolor, C. quince, C. album and C. koreanse expressed chlorotic local lesions on inoculated leaves 11-12 days after mechanical inoculation with infective sap. The remaining 22 species showed no symptoms and no virus was recovered from them whet back-inoculated to C. amaranticolor. 4. Among the four species of Chtnopodium mentioned above, C. amaranticolor and C. quinoa appear to be the most suitable local lesion test plants for garlic mosaic virus. 5. Cloves and top·sets originating from mosaic infected garlic plants were $100\%$ infected with the same virus. Consequently the garlic mosaic virus is successively transmitted through infected cloves and top-sets. 6. Garlic mosaic virus was mechanically transmitted to C, amaranticolor when inoculations were made with infective sap of cloves and top-sets. 7. Physical properties of the garlic mosaic virus as determined by inoculation onto C. amaranticolor were as follows. Thermal inactivation point: $65-70^{\circ}C$, Dilution end poiut: $10^-2-10^-3$, Aging in vitro: 2 days. 8. Electron microscopic examination of the garlic mosaic virus revealed long rod shaped particles measuring 1200-1250mu. 9. Garlic mosaic virus was purified from leaf materials of C. amaranticolor by using two cycles of differential centrifugation followed by Sephadex gel filtration. 10. Garlic mosaic virus was successfully detected from infected garlic cloves and top-sets by a serological microprecipitin test. 11 Serological tests of 150 garlic cloves and 30 top-sets collected randomly from seperated plants throughout five different garlic growing regions in Korea revealed $100\%$ infection with garlic mosaic virus. Accordingly it is concluded that most of the garlic cloves and top-sets now being used for propagation in Korea are carriers of the garlic mosaic virus. 12. Serological studies revealed that the garlic mosaic virus is not related with potato viruses X, Y, S and M. 13. Because of the difficulty in securing mosaic virus-free garlic plants, direct inoculation with isolated virus to the garlic plants was not accomplished. Results of the present study, however, indicate that the virus isolate used here is the causal virus of the garlic mosaic disease in Korea.

• Korean journal of applied entomology
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• v.14 no.3 s.24
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• pp.97-109
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• 1975

In an attempt to develop an effective integrated system of controlling blast disease of rice caused by Pyricularia oryzae Cav., the possibility of minimizing the disease incidence by proper application of fertilizers has been investigated. Thus the effect of silicate, nitrogen, phosphorus and potassium fertilizers on the development of blast disease as well as the correlation between the rice varieties an4 strains of P. oryzae were studied. The experiments were made in 1971 and 1973 by artificial inoculation and under natural development of the blast disease on rice plants. The results obtained are summarized as follows. 1. Application of silicate fertilizer resulted in the increase of silicate as well as total sugar and potassium content but decrease of total nitrogen and phosphorus in tile leaf blades of rice plants. 2. The ratios of total C/total N. $ SiO_2/total$ N, and $K_2O/total$ N in leaf blades of rice plants increased by the application of silicate fertilizers. There was high level of negative correlation between the ratios mentioned above and the incidence of rice blast disease. 3. Application of silicate fertilizer reduced the incidence of rice blast disease. 4. The over dressing of nitrogen fertilizer resulted in the increase of total nitrogen and decrease of silicate and total sugar content in leaf blades, thus disposing the rice plants more susceptible to blast disease. 5. Over dressing of phosphorus fertilizer resulted in the increase of both total nitrogen and Phosphorus, and decrease of silicate content in the leaf blades inducing the rice plants to become more susceptible to blast disease. 6. Increased dressing of potash resulted in the increase of silicate content and $K_2O/total$ N ratio but decrease of total nitrogen content in leaf blades. When potassium content is low in the leaf blades of rice plants, the additional dressing of potash to rice plant contributed to the increase of resistance to blast disease. However, there was no significant correlation between additional potassium application and the resistance to blast disease when the potassium content is already high in the leaf blades. 7. When four rice varieties were artificially inoculated with three strains of P. oryzae, the incidence of blast disease was most severe on Pungok, least severe on Jinheung and moderate on Pungkwang and Paltal varieties. 8. Disease incidence was most severe on the second leaf from top and less sever on top and there leaf regardless of the fertilizer application when 5-6 leaf stage rice seedlings of four rice varieties were artificially inoculated with three strains of P. oryzae. 9. The pathogenicity of three strains of P. oryzae was in the order of $P_1,\;P_2,\;and\;P_3$ in their virulence when inoculated to Jinheung, Paltal, Pungkwang varieties but not with Pungok. The interaction between strains of P. oryzae and rice varieties was significant.

• Korean journal of applied entomology
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• v.16 no.4 s.33
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• pp.199-208
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• 1977

Activities of various hydrolytic enzymes produced by three plant pathogenic fungi, Sclerotium rolfsii Sacc., Sclerotinia sclerotiorum (Lieb.) deBary and Helminthosporium sigmoideum var. irregulare Crallery et Tullius, were measured. Activties and amounts of the enzymes in mycelia, cultural filtrates, and sclerotia(except of sclerotia of H. sigmoideum var. irregulare) were estimated at various pH levels in order to find out optimal pH for their enzymatic activities. Enzymes such as cellulase (ex), invertase, xylanase, $\beta-amylase$, polymethylgalacturonase, polygalacturonase, phosphatase and protease were estimated. Culture solution for production of enzymes was prepared by adding of 10g, D-glucose, 1.3g $NH_4NO_3,\; 0.5g\; MgSO_4,\;7H_2O,\; and\; 1.0g\; KH_2PO_4$ into 1 liter of potato decoction plus 2ml of micro element solution consisting of 0.2mg. Fe, 0.2mg Zn, and 0.1mg Mn as the sulphates into 1 liter of distilled water. All tested mycelia and cultural filtrates were obtained from the cultures incubarted in previous solution for ten days at $25^{\circ}C$, and sclerotia were harvested from PDA plates of 3. days old, The crude enzyme solutions were prepared according to the method of Miyazaki etal. Ten days after incubation, activities of Cx produced by Scl. sclerotiorum were higher than those of the other fung and each of Cx from three fungi showed different pH optima, such as S. rolfsii and Scl. schlerotiorum in acid side (around pH 3.0), H. sigmoideum var. irregulare in neutral side (around pH 6.3). Invertase activities of S. rolfsii were 20 times higher than those of the other fungi in all samples. All tested fungi, however, showed no significant difference between the enzymatic activities of their cultural filtrate and mycelia and the activities in sclerotia of S. rolfsii and Scl. sclerotiorum were hardly recognized. There were multiple peaks on the xylanase activity curves of three fungi in terms of pH values. High activities of the xylanase were revealed in sclerotia of S. rolfsii and Scl. sclerotiorum, and in mycelia of H. sigmoideum var. irregulare. The highest activities of $\beta-amylase$ were shown both in mycelia and cultural filtrate of H. sigmoideum var. irregulae among the tested fungi, and their optimal pH was 6.2 in both mycelia and cultural filtrate. In the S. rofsii and Sel. sclerotiorum, however, the activities of cultural filtrates were higher than those of the other fungi, and optimal pH was 3.0 and 6.2 for cultural filtrate and both mycelia and sclerotia, respectively. Activities of PMG were high in cultural filtrates of all tested fungi, especially in Scl. sclerotiorum and H. sigmoideum var. irregulare. Mycelia of themalso showed the considerable activities. Optimal pH for enzymatic activities were variable with thekind of fungi or with the samples measured. The highest activities of PG were presented by mycelia of S. rolfsii and Scl. sclerotiorum. $9.l\mu /min.\; and\; 9.5\mu g/min.$, respectively. Optimal pH for activity of PG in mycelia was around 4.5 in S. rolfsii and around 3.0 in Scl. sclerotiorum. Phosphatase of S. rolfsii and Scl. sclerotiorum was more active in acid side (optimal PH3. 5) and that of H. sigmoideum var. irregulare showed one peak each in acid, neutral and alkaline side. But the highest peak was at pH 9.5. Protease of all tested fungi was more active at pH 10.0, especially that of the cultural filtrate of H. sigmoideum var. irregualre.

• Korean journal of applied entomology
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• v.9 no.2
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• pp.57-74
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• 1970

These experiments were conducted to investigate the :actors influencing the systemic action of Dimethoate (O,O-dimethyl-S-(N-methylcarhamoylmethyl) photphorodithioate) to rice seeds and the phytotoxic effects on the seed germination. Dimethoate $(Roxion^{(R)})$ $40\%$ emulsion was used. The varieties tested were Jinheung. Nongkwang,Suwon #82, Norm #6, Paltal, Shirogane, Suseong, Pungkwang, Shin #2, Fujisaka #5, Kwanok, and Jaekeun. The permeated Dimethoate was extracted from the treated seeds by chloroform and quantities were determined by Spectrophotometer. The phytotoxicity was evaluated from the effects on the germination of the treated seeds which were kept in an incubator. The oxygen consumption was measured by Warburg Manometer at $30^{\circ}C$ for 60 minutes. Indices of KOH disintegration of seeds and chemical composition of the seeds were also determined. The results obtained were as followings; 1) The amount of permeated Dimethoate in the seeds showed remarkable differences with varieties. The amount of Dimethoate per 100 grains was greater as in the ascending order of Suseong, Kwanok, Nongkwang, Jinheung, Paltal, Fujisaka #5, Suwon #82, Norm #6, Shirogane, Shin #2, Pungkwang and Jaekeun. 2) It was observed that the total amount of Dimethoate in the seeds(mg./100 grains) were greater among the varieties with large grain than those with small grains, while reverse cases were true in the amount of Dimethoate in a gramme of seeds, probably because of the greater surface areas In a small grains for a gramme weight. 3) There was no significant correlation between the permeated amount of Dimethoate and amount of absorbed water by the seeds when the seeds were treated with $0.1\%$ Dimethoate for 24 and 48 hours. 4) The permeability of Dimethoate to seeds significantly increased in the prolonged soaking periods, higher concentration, and higher temperature. 5) When the seeds were treated with $0.1\%$ Dimethoate for 24 and 48 hours at $15^{\circ},\;20^{\circ},\; 20^{\circ},\; and \;30^{\circ}C$, the permeated amount of Dimethoate were increased at higher temperature. It seems to be that the more active penetration of Dimethoate was involved at the higher temperature. 6) The phytotoxic effects of Dinethoate on the seed germination varied with the varieties. An descending order of varietal tolerance of seeds was as followings: Jinheung, Fujisaka #5, Suwon #82, Paltal, Nongkwang, Jaekeun, Shin #2, Kwanok, Shirogane, Pungkwang, Suseong, and Norm #6. 7) There was a positive correlation between the amount of Dimethoate permeated into the seeds (mg./gram. of seeds) and phytotoxicity of seeds. 8) The Phytotoxic effects of Dimethoate showed close correlation with the degree of KOH disintegration of seeds, average germination periods, and oxygen respiration of seeds. 9) It was observed that higher protein contents of the seeds decreased the phytotoxic effects of Dimethoate. 10) Relatively high negative correlation between the degree of KOH disintegration of seeds and crude protein content of the seeds was observed. 11) The average germination period was delayed for about 2 days when the seeds were treated with $0.2\%$ Dimethoate for 24 hours at $30^{\circ}C$. 12) The oxygen consumption of the seeds treated with $0.2\%$ Dimethoate for 24 hours at $30^{\circ}C$ was greatly decreased when compared with that of the normal seeds. 13) The amount of oxygen consumption of the seeds (in 24 hours after 24 hours water soaking) was negatively correlated with the average germination periods of the seeds.

• Korean journal of applied entomology
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• v.16 no.3 s.32
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• pp.171-179
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• 1977

Since the outbreak of the brown planthopper (Nilaparvata lugens) in 1915 caused tremendous losses in rice production, one of the more effective method of prevention of such a disaster could be the establishment of longterm forecasting system, In 1916 the author indicated there was a correlation between sunspot activities and brown planthopper and the white back planthopper outbreaks. However, the examples seem to be too small size to state a definite correlation. The purpose of the present study IS to revi~w the history of the brown planthopper outbreaks, and to establish a more effective forcasting system. The present forcasting methods are based on light trap catches of adults which already migrate into this country from mainland China. The regular cycle of 11.2 years of sunspot activity began in 1710, and was continued to present. To gather more records of brown planthopper, the author checked 'Joseon Wangjo Silrok' and analized the so-called 'Hwang' 'Hwang-chung' and 'Chung' which have multiple meanings, together with 'Samguk Sagi' 'Goryo Sa' and 'Munheon Bigo.' The results obtained by the about from review of these old literature citations revealed that ten species of insect and unknown species were involved: i. e., pine moth (Dendrolimus spectabilis), army worm (Mythimna separata), brown planthopper (Nilarvata lugens), white-back planthopper (Sogatella furcifera), migratory locust (Locutsa migratoria), rice stem borer (Chilo suppressalis,), mole cricket (Gryllotalpa africana), rice-plant weevil (Echinocnemus squameus), cut worm (Euxoa segetum), and mulberry pyralid Margaronia pyloalis) The suspected incidence of planthopper in old records expressed by 'Hwang' or 'Chung' revealed a total or 25 out of 37 in 'Samguk sagi,' 21 out of 49 in 'Goryo sa,' 9 of 73 in 'Wanjo-silrog,' and none of 8 in 'Munheon bigo' were planthoppers. Therefore, a total of 36 out of 167 records of insect incidence in the old literature can be possibly attributed to planthoppers. The brown planthopper and white-back planthopper migrate together to Korea every year from mainland China, However, the number of each species are differ by year. In 1975 outbreak the brown planthopper was dominant; and the white-back planthopper prevailed in 1946 and 1977 outbreaks, During the course of this study, the author was able to add a new record of outbreak of planthop per. In 1916 the white-back planthopper outbreak caused serious losses in Chungcheong-namdo and Jeonla-namdo, with losses estimated as high as 160 and 190 thousand seok (23.2 and 27.5 thousand M/T), in Naju and Secheon county, respectively. Since 1912, major outbreaks of brown planthopper or white-back planthopper have been recored 5 times. These occurrences coincide and well matched the period of minimum number of sunspots, With these authenticated records of planthoppers, the author believes there is a close correlation between brown planthopper and white-back planthopper outbreaks in Korea and sunspot activities. Therefore, in years of low number of sunspots, we should watch for and expect outbreaks of these. insects. At this time, it will be necessary to provide all possible prevention measures.

• Korean journal of applied entomology
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• v.26 no.1 s.70
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• pp.13-23
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• 1987

This study was conducted to know the effects of temperature conditions on the growth and oviposition of the brown planthopper(BPH), Nilaparvata lugens $St{\aa}l$. Results obtained were to predict the timing of the BPH control by measuring population dynamics of the BPH in response to temperature fluctuations upon migration of the insects in paddy fields. Developmental and ovipositional rates under constant and alternating temperature conditions were observed in a plant growth cabinet. Hatchabilities of eggs of the BPH were the highest at $25^{\circ}C$ and were decreased below or above the optimum temperature. Egg periods were the shortest at $27.5^{\circ}C$ and prolonged with decreasing temperature, but retarded at higher temperature above $30^{\circ}C$. Adult emergence rates were the highest at $27.5^{\circ}C$ and reduced with decreasing temperature, and no adult emerged at $32.5^{\circ}C$ and $35^{\circ}C$. Developmental period of nymph was the shortest at both $27.5^{\circ}C$ and $30^{\circ}C$, but extended with decreasing temperature. Female longevity was increased with decreasing temperature and the male longevity was the shortest at $27.5^{\circ}C$. Preoviposition period was the shortest at $32.5^{\circ}C$, but prolonged with decreasing temperature. It was about 6.5 times longer at $17.5^{\circ}C$ than that at $32.5^{\circ}C$. Number of eggs oviposited per female was the greatest at $25^{\circ}C$, but decreased at the temperature below or above the optimum. Under the same total effective day-degrees, hatchabilty at the alternating temperature was about 10% higher than that at the constant temperature but egg period at the alternating temperature was nearly identical as that at the constant. Under the $22^{\circ}C$ condition, emergence rate was about 8% higher at the alternating temperature than that at the constant, however, at the $28^{\circ}C$, the rate was about 8% higher at the constant than that at the alternating. Nymphal period was about $4{\sim}6$ days longer at the alternating temperature than that at the constant. Under the same total effective day-degrees in adult stage, both longevity and oviposition period were longer at alternating temperature than those at the constant. Number of eggs oviposited per female was also higher at the alternating. Longevities of females reared under $28^{\circ}C$ of constant temperature was the longest no matter what temperatures they were exposed after the emergence. This result seems to be indicating that female longevity is greatly influenced by the temperature to which they were exposed durings immature stages. Preoviposition period was affected by the temperature exposed during the nympal and adult stage whereas the number of eggs oviposited was affected by the temperature during the adult stage only. Based on the results from this study, the developmental threshold temperatures seem to be $14.12^{\circ}C$ for eggs, $14.76^{\circ}C$ for nymphs, $9.62^{\circ}C$ for adults, and $15.95^{\circ}C$ for preoviposition period. Estimated values of the total effective temperature for completing each stage were 141.25 day-degrees for eggs, 167.83 day-degrees for nymphs, 349.64 day-degrees for adults, and 58.60 day-degrees for preoviposition.