• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.428-439
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• 2015

Pepper anthracnose caused by Collectotrichum acutaum has been known as one of the most damaging diseases of pepper, which has reduced not only yield but also quality of pepper produce almost every year. This study was conducted to develop control strategy against pepper anthracnose by alternate application of agricultural organic materials and chemical fungicides. The alternate application effect of agricultural organic materials and chemical fungicides for controlling pepper anthracnose were examined in vitro and in the field. First, thirteen microbial agents and twenty two agricultural organic materials were screened for antifungal activity against C. acutatum through the dual culture method and bioassay. As a result, one microbial agent (Bacillus subtilis QST-713) and three agricultural organic materials (sulfur, bordeaux mixture, marine algae extracts) were found to show high inhibition effect against C. acutatum. In the field test, when Iminoctadine tris+thiram, a chemical fungicide for controlling pepper anthracnose, was sprayed, it reduced disease incidence by 89.5%. Meanwhile Sulfur, bordeaux mixture, copper, marine algae extracts and Bacillus subtilis QST-713 showed low disease incidence at the range of 33.1~81.0%. However, when Iminoctadine tris+thiram and agricultural organic materials(bordeaux mixture, marine algae extracts) were applied to pepper fruits alternately two times at 7 days interval, there was a 81.7 and 87.1% reduction in disease, respectively. Consequently, the alternate spray of chemical fungicide (Iminoctadine tris+thiram) and agricultural organic materials (bordeaux mixture, marine algae extracts) could be recommended as a control method to reduce the using amount of chemical fungicide.

• Korean Journal of Environmental Biology
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• v.32 no.2
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• pp.112-117
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• 2014

Predation efficiency and preference of the hydrophilid water beetle, Hydrochara affinis (Coleoptera: Hydrophilidae), larvae on two mosquito species, Culex pipiens molestus and Ochlerotatus togoi, were tested under laboratory conditions. Experiments were conducted in a transparent cylindrical plastic container (diameter, 100 mm; height, 40 mm; water level, 15 mm) for 24 hours (16 h, light; 8 h, dark) at $25^{\circ}C$. The predation efficiency of H. affinis on mosquito larvae was investigated under various prey conditions (1, 2, 4, 8, 16, 32, 64, and 128 larvae) with five replicates. Further, in order to investigate the prey preference on two mosquito species, each 32 larvae of C. pipiens molestus and O. togoi were provided simultaneously for the first instar larva of H. affinis with 5 replicates. As a result, the predation curves of H. affinis on two mosquito species were logarithmic; and the number of consumed prey increased as the number of predator instars were increased. As predicted from the predation curves, the estimated maximum number of C. pipiens molestus and O. togoi consumed by a third instar larva of H. affinis per a day was 926 and 304 larvae, respectively. As predicted from the Holling's disk equation, the differences in consumed prey number between predator instars and prey species were caused by handling time rather than attack rate. Handling time decreased rapidly as the predator larvae grew, and that of O. togoi was twice longer than that of C. pipiens molestus.

• Research in Plant Disease
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• v.23 no.2
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• pp.159-167
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• 2017

This study was conducted to evaluate the control efficacy of the organic farming materials on cucumber scab caused by Cladosporium cucumerinum PT1 (KACC 48094). The antifungal activities in vitro as well as the suppressive effect of 43 organic farming materials on the spore germination and germ tube growth by inoculating spore suspension on cucumber seedlings in vivo were investigated. Thirteen organic farming materials inhibited the mycelial growth of C. cucumerinum and nine of these were microbial agents. In the screening using cucumber seedlings, six organic farming materials were very effective with control efficacy value of 90%. Among them, Bacillus amyloliquefaciens M27 provided suppressive effect on both mycelial growth and spore germination against cucumber scab. Finally, nine organic farming materials were selected to test the protective and curative effects, and all chosen organic farming materials significantly suppressed disease incidence when applied in the preventive action, in comparison with the curative action. Especially, Bordeaux mixture I and III gave excellent protective control efficacy with control values of 96.7% and 73.3%, respectively, whereas its curative control effect was significant low. Among these, only Thymus quinquecostatus+Sophora extract showed curative activity, although the control value was as low as 50%. This study suggests that cucumber scab can be controlled by some organic farming materials in the farmhouses under comparatively cold and wet condition and protective treatment is more important and efficient.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.345-355
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• 2017

This study was conducted to evaluate rice seed disinfection efficacy of loess-sulfur for the suppression of Bakanae disease caused by Fusarium fujikuroi. Rice seeds were treated at different concentrations of loess-sulfur, soaking time and temperature, and combination of hot-water treatment. Rice cultivar, Shindongjin harvested from Bakanae disease-infested area in 2015, was used. Loess-sulfur was treated as follows; concentration of undiluted solution, 2%, 1% and 0.5%; soaking time of 24 and 48 hours; treatment temperature of $20^{\circ}C$ and $30^{\circ}C$; hot water treatment or not. Optimal conditions of rice seed disinfection were selected soaking time of 48 hours and the suspension of 0.5% and 1% loess-sulfur by investigating seed germination and isolation frequency of Fusarium spp. on Komada agar medium in vitro, and were established 3 disinfection conditions as hot water ($60^{\circ}C$, 10 min.) + 1% loess-sulfur ($20^{\circ}C$, 48 hours), 1% loess-sulfur only ($30^{\circ}C$, 48 hours) and 1% loess-sulfur only ($20^{\circ}C$, 48 hours) through additional test in greenhouse. Above 3 conditions were verified by rice seedling box and paddy field test in the way of investigating Bakanae diseased plants (%) and healthy plants (%). Consequently, most effective rice seed disinfection conditions on Bakanae disease were combination of hot water and 1% loess-sulfur and loess-sulfur only at $30^{\circ}C$. Furthermore, treatments with these conditions showed control value of 100% were maintained from seedling to the heading stage in the field. However, treatment of 1% loess-sulfur only at $20^{\circ}C$ showed low control value of 78.2% in paddy field. Hot water only treatment turned out to be an effective disinfection method when conducted thoroughly with $60^{\circ}C$, 10 min. However, it was thought additional soaking process with loess-sulfur after hot water treatment served more high control effect against Bakanae disease when rice seeds were disinfected on a large scale. This results expected rice seed disinfection with loess-sulfur were effectively and easily usable method if farmers had only one of either hot water-disinfector or seed-disinfector. In addition, loess-sulfur is well-known to farmers, simple to manufacture method and cheap.

• Korean journal of applied entomology
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• v.24 no.4 s.65
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• pp.195-201
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• 1986

This study was conducted to investigate the life history of Compsidia populnea which is major species of the stem-borers on Populus alba{\times}glandulosa$. Peak emergence of the adult of Compsidia populnea L. was around 10th${\sim}$l2nd of May in Chuncheon vicinities, having one generation a year in Korea. There was a preovipositional period of 10.7 days and a ovipositional period of 14.3.days. Mean adult longevity was 11 days for male and 13.8 days for female. Individual eggs were long oval with somewhat narrowed tip at one side and soft, 2.6mm in length, 0.8mm in diameter, and were laid singly under the U-shaped scars which were made by female before oviposition. Total number of scars per female averaged 56.6 ($8{\sim}135$) and eggs were found in 67.9 percent of the total scars. Egg period was $8{\sim}11$ days at $25^{\circ}C$ constant temperature and $7{\sim}14$ days in the field condition. Early young larvae stayed for $2{\sim}3$ weeks under the scars and then boring into the xylem, forming galls at this time. Size of the gall was 1.8cm($1.3{\sim}2.5$) in length, 1.6cm($1.0{\sim}2.2$) in diameter and the length of mine was everage 3.1cm. Fully grown larvae were developed around the early October and overwintered in the mines of galls. Pupation was done around the early of April. Pupal developmental period averaged 11 days($9{\sim}13$ days) at $25^{\circ}C$ constant temperature condition.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.71-82
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• 2006

One of the most popular pre-reinforcement methods of tunnel heading in cohesionless soils would be the fore-polling of grouted pipes, known as RPUM (reinforced protective umbrella method) or UAM (umbrella arch method). This technique allows safe excavation even in poor ground conditions by creating longitudinal arch parallel to the tunnel axis as the tunnel advances. Some previous studies on the reinforcing effects have been performed using numerical methods and/or laboratory-based small scale model tests. The complexity of boundary conditions imposes difficulties in representing the tunnelling procedure in laboratory tests and theoretical approaches. Full-scale study to identify reinforcing effects of the tunnel heading has rarely been carried out so far. In this study, a large scale model testing for a tunnel in granular soils was performed. Reinforcing patterns considered are four cases, Non-Reinforced, Crown-Reinforced, Crown & Face-Reinforced, and Face-Reinforced. The behavior of ground and pipes as reinforcing member were fully measured as the surcharge pressure applied. The influences of reinforcing pattern, pipe length, and face reinforcement were investigated in terms of stress and displacement. It is revealed that only the Face-Reinforced has decreased sufficiently both vertical settlement in tunnel heading and horizontal displacement on the face. Vertical stresses along the tunnel axis were concentrated in tunnel heading from the test results, so the heading should be reinforced before tunnel advancing. Most of maximum axial forces and bending moments for Crown-reinforced were measured at 0.75D from the face. Also it should be recommended that the minimum length of the pipe is more than l.0D for crown reinforcement.