• Korean journal of applied entomology
• /
• v.46 no.3
• /
• pp.349-356
• /
• 2007

Three active components (Z8-12:Ac, E8-12:Ac, and Z8-12:OH) are known in sex pheromone of the oriental fruit moth, Grapholita molesta, and have been commercially available to apply for population monitoring and mating disruption. However, there have been variation among commercial products in pheromone composition and amount impregnated in each pheromone releaser. This study was performed to optimize factors influencing on pheromone monitoring of G. molesta by analyzing pheromone composition/amount, effective period of releaser, and trap type/placement in apple trees. High purity of Z8-12:Ac component was effective to attract males, in which 96% or more of cis acetate isomer component appeared to be optimal composition. Pheromone amounts ($0.01-1\;{\mu}g$) impregnated in each rubber dispenser did not give significant effect on monitoring during 90 days from June to August. "Delta" trap was much more efficient than "cone" trap to collect males. Trap installation was another factor, in which placing traps at canopy level was much efficient than at trunk or ground levels. Pheromone trap monitoring with these optimal factors indicated three to four adult peaks from June to September in addition to high overwintering population from April to May in pesticide-applied orchards in Andong, Korea.

• The Korean Journal of Pesticide Science
• /
• v.15 no.1
• /
• pp.61-67
• /
• 2011

In 2010, two-spotted spider mite, Tetranychus urticae was collected from the rose greenhouse and apple orchards in Cheongju (CJ), Chungju (CUJ)-1, CUJ-2, Kangjin (KJ), Yesan (YS), and Yeongju (YJ). Among them, KJ and YS strain showed high resistance to bifenazate of 964.5- and 1l30-fold, respectively. The other strains showed low resistance to bifenazate. By analyzing the mitochondrial cytochrome b (cytb) sequence, G126S point mutation was detected in KJ and YS strain. Thus, G126S point mutation in the mitochondrial cytb was available molecular detection marker for selection of bifenazate resistant T. urticae. Two molecular detection methods, quantitative sequencing (QS) and PCR amplification of specific alleles (PASA) were well detected specific G126S point mutation. Therefore, these methods can be used to monitor the resistance allele in field population of T. urticae and bifenazate resistance management strategy.

• Korean Journal of Soil Science and Fertilizer
• /
• v.6 no.3
• /
• pp.141-152
• /
• 1973

The mineralogical studies of the eleven sub-soil samples derived from granite, granodiorite, diorite and arkose sandstone, taken from apple orchards in the province of Kyungsangbukdo, Korea are made to investigate the relationships between the mineral weathering, soil forming processes and mineralogical composition. The fine sand fraction (less than 0.2mm) and the clay fraction (less than 2 micron) are dispersed with the shaker after hydrogen peroxide treatment for the removal of organic matter, and separated from each suspension by gravity sedimentation. The fine sand are observed by mineral microscope and the clay are observed by X-ray diffraction patterns, differential thermal analysis curves and infrared spectrum. The outline of the results are as follows. 1. The primary minerals ; Quartz, changed-feldspar, plagioclase, alkali-feldspar are dominant in almost all samples, and some samples contain an appreciable amount of hornblende, biotite, muscovite and plant opal. There are also those samples which contain very small quantity of pyroxene group, tourmaline, epidote, cyanite, magnetite, volcanic glass and zircon. They are mainly derived from weathering products of granite, granodiorite, diorite, arkose or its mixtures. 2. All samples contain expanding or nonexpanding $14{\AA}$ minerals, illite and kaolin minerals, and some samples contain chlorite, cristobalite, gibbsite, and those primary minerals as quartz and feldspar, but the quantities vary according to the parent matrials. 3. Non-expanding $14{\AA}$ minerals may be dioctahadral vermiculite which sandwiches gibbsite layer or chlorite in between layer lattices. 4. As for clay minerals, montmorillonite was principal component in the samples derived from weathering products of arkose sandstone and tertiary. Minerals which are derived from weathering products of arkose have kaolin minerals and vermiculite as their principal component, and minerals derived from weathering products of acidic rock group are generally classified into two groups, the kaolin mineral group, and the kaolin minerals and vermiculite group.

• Research in Plant Disease
• /
• v.29 no.1
• /
• pp.23-38
• /
• 2023

The fire blight caused by Erwinia amylovora (Ea) is a devastating disease of Rosaceae plants, including commercially important apple and pear trees. Since the first report in Korea in May 2015, it has been spreading to neighboring regions gradually. Host plants can be infected by pollinators like bees, rainfall accompanied by wind, and cultural practices such as pruning. Many studies have revealed that wild Rosaceae plants such as Cotoneaster spp., Crataegus spp., Pyracantha spp., Prunus spp., and Sorbus spp. can be reservoirs of Ea in nature. However, wild Rosaceae plants in Korea have not been examined yet whether they are susceptible to fire blight. Therefore, the susceptibility to fire blight was examined with 25 species in 10 genera of wild Rosaceae plants, which were collected during 2020-2022, by artificial inoculation. Bacterial suspension (10⁸ cfu/ml) of Ea type strain TS3128 was inoculated artificially in flowers, leaves, stems, and fruits of each plant species, and development of disease symptoms were monitored. Moreover, the presence of Ea bacteria from inoculated samples were checked by conventional polymerase chain reaction. Total 14 species of wild Rosaceae plants showed disease symptoms of fire blight, and Ea bacteria were detected inside of inoculated plant parts. These results suggest that wild Rosaceae plants growing nearby commercial apple and pear orchards in Korea can be Ea reservoirs, and thus they should be monitored regularly to minimize the damage by Ea infection and spreading.

• Research in Plant Disease
• /
• v.28 no.4
• /
• pp.221-230
• /
• 2022

The fire blight caused by Erwinia amylovora (Ea) was first reported in 2015 in Korea, and the disease has rapidly spread to 22 regions until 2021. In Korea, all host plants in the apple and pear orchards where fire blight occurred should be eliminated and buried by the Plant Protection Act. To prevent the spread of the disease, all burial sites were prohibited from planting the new host plants for the next three years. To confirm the eradication efficiency of Ea and the reoccurrence of fire blight, the surveillance facilities were established on three burial sites from 2019 to 2020 in Anseong-si, Gyeonggi-do, and Chungju-si, Chungcheongbuk-do. As host plants, five apple trees of fire blight-susceptible cultivar 'Fuji', were planted in each facility. All facilities were enclosed with fences and nets and equipped with two CCTVs, motion sensors, and several other sensors for recording weather conditions to monitor the environment of the sentinel plants in real-time. The sentinel plants were checked for the reoccurrence of fire blight routinely. Suspicious plant parts were collected and analyzed for Ea detection by loop-mediated isothermal amplification polymerase chain reaction and conventional polymerase chain reaction. Until November 2022, Ea has not been detected in all sentinel plants. These results might support that the burial control of infected plants in soil works efficiently to remove Ea and support the possibility to shorten the prohibition period of host plant establishment in the burial sites.

• Korean Journal of Soil Science and Fertilizer
• /
• v.10 no.3
• /
• pp.103-134
• /
• 1977

The physiological and biochemical role of potassium for upland crops according to recent research reports and the nutritional status of potassium in Korea were reviewed. Since physical and chemical characteristics of potassium ion are different from those of sodium, potassium can not completely be replaced by sodium and replacement must be limited to minimum possible functional area. Specific roles of potassium seem to keep fine structure of biological membranes such as thylacoid membrane of chloroplast in the most efficient form and to be allosteric effector and conformation controller of various enzymes principally in carbohydrate and protein metabolism. Potassium is essential to improve the efficiency of phoro- and oxidative- phosphorylation and involve deeply in all energy required metabolisms especially synthesis of organic matter and their translocation. Potassium has many important, physiological functions such as maintenance of osmotic pressure and optimum hydration of cell colloids, consequently uptake and translocation of water resulting in higher water use efficiency and of better subcellular environment for various physiological and biochemical activities. Potassium affects uptake and translocation of mineral nutrients and quality of products. potassium itself in products may become a quality criteria due to potassium essentiality for human beings. Potassium uptake is greatly decreased by low temperature and controlled by unknown feed back mechanism of potassium in plants. Thus the luxury absorption should be reconsidered. Total potassium content of upland soil in Korea is about 3% but the exchangeable one is about 0.3 me/100g soil. All upland crops require much potassium probably due to freezing and cold weather and also due to wet damage and drought caused by uneven rainfall pattern. In barley, potassium should be high at just before freezing and just after thawing and move into grain from heading for higher yield. Use efficiency of potassium was 27% for barley and 58% in old uplands, 46% in newly opened hilly lands for soybean. Soybean plant showed potassium deficiency symptom in various fields especially in newly opened hilly lands. Potassium criteria for normal growth appear 2% $K_2O$ and 1.0 K/(Ca+Mg) (content ratio) at flower bud initiation stage for soybean. Potassium requirement in plant was high in carrot, egg plant, chinese cabbage, red pepper, raddish and tomato. Potassium content in leaves was significantly correlated with yield in chinese cabbage. Sweet potato. greatly absorbed potassium subsequently affected potassium nutrition of the following crop. In the case of potassium deficiency, root showed the greatest difference in potassium content from that of normal indicating that deficiency damages root first. Potatoes and corn showed much higher potassium content in comparison with calcium and magnesium. Forage crops from ranges showed relatively high potassium content which was significantly and positively correlated with nitrogen, phosphorus and calcium content. Percentage of orchards (apple, pear, peach, grape, and orange) insufficient in potassium ranged from 16 to 25. The leaves and soils from the good apple and pear orchards showed higher potassium content than those from the poor ones. Critical ratio of $K_2O/(CaO+MgO)$ in mulberry leaves to escape from winter death of branch tip was 0.95. In the multiple croping system, exchangeable potassium in soils after one crop was affected by the previous crops and potassium uptake seemed to be related with soil organic matter providing soil moisture and aeration. Thus, the long term and quantitative investigation of various forms of potassium including total one are needed in relation to soil, weather and croping system. Potassium uptake and efficiency may be increased by topdressing, deep placement, slow-releasing or granular fertilizer application with the consideration of rainfall pattern. In all researches for nutritional explanation including potassium of crop yield reasonable and practicable nutritional indices will most easily be obtained through multifactor analysis.

• Korean journal of applied entomology
• /
• v.24 no.4 s.65
• /
• pp.183-190
• /
• 1986

Identification of fruit sucking moths, their larval host plant, and degree of damages to fruits were investigated in $1982{\sim}'83$ at two orchards in Cheonnam province. In this study, 4 families 30 species were collected as fruit sucking moths and among them 10 species are newly recorded in Korea as fruit sucking moth: Catocala electa(B.), Spirama helicina(H.), Erebus ephesperis(H.), Parallelia stuposa(F.), Simplicia niphona(B.), Marumba gaschkewitschii(B. et G.), Agrius convolvuli(L.), Thyatira batis (L.), and Spilosoma niveum(M.). Larval host plants of fruit sucking moths in the vicinity of the fruit orchard include Cocculus trilobus D., Albizzia julibrissin D., Pterocarya rhoifolia S., Jaglans mandshurica M., Solanum melongena L., Brassia campestris S., Rubus idaeus C., Thalictrum aquilegifol L., and Rhus succedanea L. As the damage on different varieties of the main fruit trees, plum was orderly Santa Rosa>Beauty, Apple was Chook>Hong Og, Peach was Choseng Baeg Do>Hwang Do>Baeg Do, and Grape was Campbell Early>Neo Mascat>Golden Queen. Seasonal occurrence of main fruit sucking moth Spirama retorta(C.) showed peak 3 times in early-July, late-July, early-September. Oraesia emerginata(F.) showed peak 3 times in late-July, early-August, early- September and Lagoptera juno(D.) showed peak only in late-July and Adrias tyrannus amurensis(S.) showed peak only in mid-July. Fruit sucking moths were immigrated from p.m. 6 to a.m. 2, with peak in p.m. 10 to p.m. 12.