Sung-Tae Park

Susceptibility of Stink Bugs Collected in Soybean Fields in Milyang to Some Insecticides

The susceptibility of five stink bugs species collected soybean fields in Milyang in 2006 to seven insecticides was evaluated using electric auto-sprayer. The insecticide deltamethirn had the lowest median lethal concentration (LC50) of 0.4 to 2.3 ppm regardless of stink bugs species while phenthoate had the highest concentration for one-banded stink bug (Piezodorus hybneri), green stink bug (Nezara antennata), sloe bug (Dolycoris baccarum), and brown marmorated stink bug, (Halyomorpha halys); and fenthion for bean bug (Riptortus clavatus). The average LC50 for stink bugs to seven insecticides was lowest at 7.5 ppm for R. clavatus, followed by 16.6 ppm for H. halys, 17.6 ppm for D. baccarum, 19.1 ppm for N. antennata, and 28.4 ppm for P. hybneri. The relative tolerance ratio (TR), which is the TR of 90 percent lethal concentration (LC90) of stink bugs to the recommended concentration, was the lowest in fipronil for R. clavatus, P. hybneri and D. baccarum; fenitrothion for N. antennata; and fenthion for H. halys. The relative average TR was lowest at 0.09 for R. clavatus, followed by 0.26 for D. baccarum, 0.30 for N. antennata, 0.37 for P. hybneri, and 0.39 for H. halys. Therefore, insecticides susceptibility was highest for R. clavatus and lowest for P. hybneri while the relative average TR was lowest for R. clavatus and highest for H. halys. Accordingly, it is expected that stink bugs can be effectively controlled with by spraying insecticides in soybean field because the relative average TR value of stink bugs was below 1.0, indicating high susceptibility of stink bugs to insecticides.

Effects of a Mungbean Cultivar, Jangannogdu on Nymphal Development, Adult Longevity and Oviposition of Soybean Stink Bugs

Nymphal development, adult longevity, and oviposition of six different species of stink bugs were compared on seeds of a soybean cultivar, Taekwangkong, and two mung bean cultivars, Kyungseonnogdu and Jangannogdu in the insect rearing room (, 16L:8D). Nymphs of six species of stink bugs normally developed on Taekwangkong seed. While nymphs of Riptortus clavatus, Halyomorpha halys, and Dolycoris baccarum developed on seeds of Kyungseonnogdu and Jangannogdu normally, all nymphs of Plautia stali, Piezodorus hybneri and Nezara antennata died after 4th instars on Kyungseonnogdu and after 3rd instars on Jangannogdu. Each instar period tended to be increased as nymphal stages were progressed. Nymphal period was shortest on Taekwangkong seed, followed by Kyungseonnogdu and Jangannogdu, irrelevant to stink bugs species. Emergence rate, adult longevity, and preoviposition period of 6 stink bugs were different depending on the reared seeds. Of 6 different species examined, Riptortus clavatus, Halyomorpha halys, and Dolycoris baccarum which fed on Jangannodu did not emerge, Plautia stali, Piezodorus hybneri, and Nezara antennata which fed on Jangannodu did not oviposit.

Seasonal Occurrence of Tobacco Cutworm, Spodoptera litura Fabricius and Beet Armyworm, Spodoptera exigua Hübner Using Sex Pheromone Traps at Different Locations and Regions in Yeongnam District

Seasonal occurrences of tobacco cutworm, Spodoptera litura and beet armyworm, Spodoptera exigua were observed using sex pheromone traps at different locations and climatic regions in Yeongnam district. In Gyeongnam province, S. litura male adults kept occur from mid or late March to mid or late November Whereas in Gyeongbuk province, S. litura occurred from mid or late April to early or mid November with exception at Uljin where it was late May to late October. According to the climatic regions, the peak occurrence of S. litura was middle September at the southern coast region, late August at the inland and the basin region, middle August at the inland mountainous region, and early September at the eastern middle coast region. The occurrence rate of S. litura was the highest at Jinju with 20.0% and the lowest at Changyeong with 8.6% in Cyeongnam province, while it was the highest at Sungju with 3.3% and the lowest at Uljin with 0.8% in Gyeongbuk province. In accordance with the climatic regions, the occurrence rate of S. litura was the highest at the inland region with 43.7%, and followed by the southern coast region (36.3%), the basin region (8.4%) and the inland mountainous region (7.0%), and was the lowest at the eastern middle coast legion with 4.6%. On the other hand, S. exigua occurred from early March to middle November with the exception of the eastern middle coast region including Pohang, Yeongdeog and U]ien in Cyeongbuk province where it occurred from mfd April to middle November. The peak occurrence of s. exigua was early August at the inland region, the basin region and the inland mountainous region, and was late of August at the southern coast region and the eastern middle coast region. The occurrence of S. exigua was the highest at Changyeong with 1.6% and the lowest at Busan with 0.4% in Gyeongnam province, while it was the highest at Sungju with 37.2% and the lowest at Uljin with 2.7% in Gyeongbuk province. The climatic regional occurrence rate of S. exigua was the highest at the basin region with 54.3%, and followed by the inland mountainous region (29.9%), the eastern middle coast region (9.3%) and the inland (3.9%), and was the lowest at the southern coast region with 2.6%. As a whole, S. litura occurred more in Gyeongnam province than Cyeongbuk province, while S. exigua occurred more in Gyeongbuk province than Gyeongnam province. According to the regions grouped by climatic differences, the occurrence of S. litura and S. exigua was the highest at the inland region in Gyeongnam province and at the basin region in Gyeongbuk province. The total number of S. litura captured by sex pheromone trap was 2.4 times higher than that of S. exigua. However, the first occurring time and the peak occurrence of S. exigua were slightly earlier than those of S. litura.

Differential Tolerance of Rice Cultivars to Mesotrione-Contained Herbicides

Greenhouse experiment was conducted to evaluate tolerance of six rice cultivars, three IndicaJaponica rice (long grain, cv. Dasanbyeo, Segejinmi and Hanareumbyeo) and three Japonica rice (short grain, Nampyung, Ilpumbyeo and Junamjosaeng) cultivars, to mesotrione+pretilachlor (MP) and bensulfuron-methyl+mesotrione+pretilachlor+pyriftalid (BMPP) in transplanting rice. Two herbicides were applied at 90 g and 180 g a.i. to three to four leaf stage rice at 5 and 15 days after transplanting, respectively. Related study was also conducted to compare for IndicaJaponica and Japonica rice cultivars at different MP rates. Response to two herbicides varied with respect to rice cultivars and herbicide rates. All IndicaJaponica rice cultivars exhibited susceptible to both MP and BMPP as reflected by increased visual injury, shorter plant height and higher plant dry matter reduction when compared with nontreated rice cutlivars. The degree of foliar chlorosis by MP at 90 g a.i. was 5~6 at 7 days after treatment(DAT) but it was decreased to 3~6 at 14DAT. The degree of leaf chlorosis treated with 180 g a.i. MP was 6~7 at 7DAT and it was also decreased to 3~8 at 14 DAT. The plant hight of IndicaJaponica rices was inhibited by 18~43% at application of 90 g a.i. MP and 30~50% at 180 g a.i. MP. The dry matter reduction was greater than that of plant height inhibition, showing 46~73% at 90 g a.i. MP and 65~82% at 180 g a.i. MP. Similar leaf chlorosis injury and growth inhibition of rice cultivars was observed in the BMPP treatment. The injury and growth inhibition by MP and BMPP increased with increase in herbicide rate from 90 g a.i. to 180 g a.i. . However, most of the Japonica cultivars are tolerant to MP and BMPP at both rates. There was no visible leaf chlorosis but plant height and dry matter production were slightly reduced at 180 g a.i. . Based on value determined in reduction of shoot dry weight for MP, the IndicaJaponica rice showed 12.9 fold lower compared with the Japonica rice. The result indicates that rice cultivars vary in tolerance to herbicides of MP and BMPP and IndicaJaponica rices were more susceptible than the Japonica rices to the MP and BMPP.

Evaluation for fracture patterns around the wrist on three‐dimensional extremity computed tomography, especially focused on the triquetrum

To describe fracture patterns of triquetrum and analyse them according to fracture classifications, anatomy of intrinsic carpal ligaments and comparison with other wrist fractures.

Selection of Bactericides for Controlling Soybean Bacterial Pustule

Bacterial pustule of soybean (Glycines max) caused by Xanthomonas axonopodis pv. glycines is one of the most prevalent bacterial diseases of soybean. This bacterium shows strong pathogenicity to the plants and distributes throughout Korea. However, no good control measures including bactericides and resistant cultivars are available to control the disease in Korea. Therefore, this study was conducted to develop chemical control method against soybean bacterial pustule. The present study was undertaken to find out the growth inhibitory effect bactericides (8 antibiotics, 2 copper compounds, quinoline, 18 agro-chemicals) on bacterial pustule pathogen. Antibiotics test showed that tetracycline and streptomycin sulfate significantly suppressed the growth of bacterial pustule pathogen. Also, application of oxolinic acid was found to be effective for pathogen inhibition. However, vancomycin, polymyxin B sulfate and copper compounds did not show the positive suppressive effect on growth of the pathogen. Among the eighteen agro-chemicals, streptomycin sulfate + oxytetracyclin (18.8 + 1.5%) WP, oxytetracycline (17%) WP and oxolinic acid (20%) WP were found to be effective for the inhibition of the pathogen in vitro. The selected 5 agro-chemicals were also applied on soybean in field and their control effects against the soybean bacterial pustule were tested. The foliar application of streptomycin sulfate + oytetracyclin WP and oxytetracycline WP on the naturally infected soybean (Taekwangkong) showed high control value (above 70%). Therefore, it is concluded that the bactericides used in this study showed strong inhibitory effect to soybean bacterial pustule and they can be recommend to farmers to control the disease.

New Alternate Host of Rice stripe virus - `Deulmuksae`

Rice stripe virus (RSV) is one of Tenuivirus Group, which is carried by small brown planthopper. There is an outbreak of RSV in South Korea at 20Ot, and 2007. The infection caused by RSV had been investigated on weeds around the rice cultivated areas 13 region and 26 site including Jeonbuk Buan and Chungnam Seocheon. There have a doubt as to alternate host of RSV is total 15 Family and 50 Species including Gramineae 24 species of Duksaepul (Alopecurus aequalis), H. sativum var. vulgare etc.. There is identified the infected RSV in Festuca myuros, Alopecurus aequalis, Hordeum sativum var. vulgare, Trisetum bifidum, Echinochloa crus-galli var. crus-galli, Digitaria ciliaris among this species. Deulmuksae is the overwintering exotic weed which sprout in Autumn and wither in Spring and commonly growed as green manure crop or cover crop. In order to identify the infection rate furthermore, 111 samples which were collected at Buan Gyehwa-myeon region, and 50 samples from Seocheon Maseo-myeon in June, 2008, were ELISA tested. The results are 32 positives from Buan, 28.8% infection rate, 8 positives from Seocheon 16.0% infection rate. RSV infection of Deulmuksae is not reported currently, and follow report first describes the Deulmuksae as an alternate host of RSV.

Reproductive Rate of Green Stink Bug, Nezara antennata Scott (Hemiptera: Pentatomidae) by the Size of Rearing Cages

The embryonic and postembryonic developments of Nezara antennata Scott were observed in 5 different rearing cages such as A (Cylindrical, ), B (Cylindrical, ), C (Rectangle, ), D (Cylindrical, 9cm in bottom & 11.5 cm in ) and E (Cylindrical, ) containing soybean and peanut seeds as food, and sponge soaked with water under laboratory condition of and 15L : 9D. Hatchability ranged from 93 to 97%. Nymphal duration was shortest of 6 days in the 1st instar and longest of 10 days in the 5th instar. The nymphal duration was 38 to 39 days observed in the rearing cages. Emergence rate was in the range from 53 to 62% with highest in A and B cages. Adult longevity was 65 to 75 days for male, and 67 to 74 days for female, and was longest in the B cage. Total number of eggs laid by female adult was in the range from 51 to 56 without significant difference in the rearing cages, and was the most in the B cage. Accordingly, the reproductive rate of N. antennata for 1 generation was within 25 to 33 times, and was highest in the B rearing cage. Therefore, it could be concluded that B cage is most suitable for stable rearing of N. antennata under laboratory condition.

Effects of Temperature on the Development and Longevity of the Gray Field Slug, Deroceras reticulatum Müller (Stylommatophora: Limacidae)

The egg size and weight of the gray field slug, Deroceras reticulatum Muller, was mm and 3.3 mg at , respectively. Its weight increased from newly laid eggs to adults for 17 weeks at four temperature regimes and was heaviest at , followed by 24, 16 and . Likewise, hatching rate of the egg batches was highest with 95% at , followed by 24, 16 and with significant differences. The number of eggs in the batches was increased with 20 at while it was only 10 at . The average accumulated egg-laying days was longest with 15 days at while shortest with 9 days at . The range of egg-laying period was shortest with 84-134 days at and longest at . Thus, the total number of eggs laid by adult D. reticulatum was highest with 217 at and lowest with 105 at . The egg period was 12-19 days while the juvenile period and adult longevity were 51-68 days and 85-134 days, respectively. The life span of D. reticulatum from egg to adult was longest with 216 days at , followed by 193 days at , 170 days at and 151 days at . Accordingly, the most favorable temperature for the oviposition, development and longevity of D. reticulatum is .

Distribution of Weeds with Different Surface Management Systems of Greenhouse Soil in Gyeongnam Province

Weed control is of fundamental importance when planting horticultural crops, particularly during the establishment phase. Weeds compete for nutrients, water and light, and can severely threaten the survival and early growth of newly planted crops. Failure to control weeds represents one of the single most important factors leading to crop loss. Knowledge on the existence of the diversity of weed species in greenhouses is of our main concern in this study in order to develop a most efficient and effective weed control strategies. Sixty-two greenhouses were surveyed in 3 cities and counties of Gyeongnam area in March to October 2009 to investigate the feature of weed occurrence in polyvinyl chloride (PVC) after harvesting of the main crops. Forty-one weed species were identified and classified to 18 families which were composed of 14 annual weeds, 18 summer annual weeds and 9 perennial weeds. On the other hand, broadleaf, grasses and sedges recorded with 30, 7 and 4 weed species, respectively. Asteraceae was the most dominant weed species (9 species) noted followed by Poaceae (7 species), Cyperaceae (4 species), Caryophyllaceae and Brassicaceae (3 species respectively) and other families have 1~2 species. The dominant weed species occurred in the greenhouse based on the summed dominance ratio. These weeds were Digitaria sanguinalis, Cyperus iria, Portulaca oleracea, Rorippa islandica, Mazus japonicas, Cardamine flexousa, and Eclipta prostrata and others. Weed occurrence in the greenhouse after horticultural crops consisted of summer annuals (4 species), winter annuals (3 species), and perennial annuals (1 specie). The dominant species occurred in tilled soil based on summed dominance ratio of weeds were Cardamine flexousa (88.1%), Eclipta prostrate (57.4%) and Portulaca oleracea (55.2%). Comparison of weed occurrence was thoroughly surveyed also in which field without PVC, weed species were Portulaca oleracea (55.2), Eclipta prostrata (57.9%) and Trigonotis peduncularis (25.1%) and field with PVC, the identified weeds were Portulaca oleracea (98.75), Trigonotis peduncularis (49.1%), and Eclipta prostrata (36.8%).