• The Plant Pathology Journal
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• v.36 no.5
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• pp.428-439
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• 2020

Erwinia pyrifoliae is a Gram-negative bacterial plant pathogen that causes black shoot blight in apple and pear. Although earlier studies reported the genome comparison of Erwinia species, E. pyrifoliae strains for such analysis were isolated in 1996. In 2014, the strain E. pyrifoliae EpK1/15 was newly isolated in the apple tree showing black shoot blight in South Korea. This study aimed to better understand the similarities and differences caused by natural variations at the genomic level between newly isolated E. pyrifoliae EpK1/15 and the strain Ep1/96, which were isolated almost 20 years apart. Several comparative genomic analyses were conducted, and Clusters of Orthologous Groups of proteins (COG) database was used to classify functional annotation for each strain. E. pyrifoliae EpK1/15 had similarities with the Ep1/96 strain in stress-related genes, Tn3 transposase of insertion sequences, type III secretion systems, and small RNAs. The most remarkable difference to emerge from this comparison was that although the draft genome of E. pyrifoliae EpK1/15 was almost conserved, Epk1/15 strain had at least three sorts of structural variations in functional annotation according to COG database; chromosome inversion, translocation, and duplication. These results indicate that E. pyrifoliae species has gone natural variations within almost 20 years at the genomic level, and we can trace their similarities and differences with comparative genomic analysis.

• Korean Journal of Organic Agriculture
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• v.18 no.4
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• pp.541-548
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• 2010

This study was established on which the selenium (Se), known as one of the functional elements in the human body, treatment was the most effective for the Se uptake in the soil and tree. Se treatments included foliar application, soil fertigation, and trunk injection. Se fertigation and control had similar soil $P_2O_5$, K, and Mg concentrations, and calcium and Se concentrations in the soil were greater on the control and Se fertigation, respectively. Leaf characteristics were not different among the treated trees. No differences were observed for the leaf K and Ca concentrations among the treated trees, and foliar Mg was greater on the Se treated trees than the control. Se foliar application and trunk injection had greater Se concentrations in the leaves and fruits than the Se fertigation and control.

• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.158-164
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• 2004

This study is to analyze the characteristics of typical Korean wood ashes from twelve trees, oak tree needles and pine bark, which are common in the area, and to suggest their applications in ash glaze making. The chemical analysis of the ashes shows that the main component of wood ash is CaO while wood bark ash consists of $SiO_2$, and leaf ash consists of CaO and $SiO_2$. The results of the study are as follows: Ashes made from the wood of Acasia, Popular and Jujube contained relatively high amounts of Fe$_2$ $O_3$ and MgO compared to other tree ashes. The ashes had yellowish green color glaze. From the result of W analysis they presented the highest chroma. Therefore these ashes are good for making transparent glaze. From the result of W analysis Grapevine, pear and oak wood ashes containing the highest amounts of Fe$_2$ $O_3$, MgO, P$_2$O$\_$5/ and MnO presented yellowish green color glaze compared to other ashes are suitable for making opaque glazes because of their showing stable and opacity phenomena. Pine tree, Platanus and Zelkova wood ashes consist of high amounts of CaO and P$_2$O$\_$5/ compared to other tree ashes. So they showed the most vivid and bluish green color glaze among 12 ashes. Therefore, they would make a good celadon glaze. Birch, oak and chestnut tree ashes have high content or MnO which affects on glaze color with small amount. These ashes presented yellowish green color not as much strong as Acacia ash, Poplar ash, Jujube tree ash. These are good for Irabo glaze.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.599-604
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• 2015

This study was conducted the vegetation clustering analysis for the 3 mountains of Mt. Bulam, Mt. Daemo, Mt. Bonghwa which were the urban forests of Seoul. Based on the results of the analysis related to the vegetation clustering, it was found that the clustering of Mt. Bulam consisted of pine trees(Pinus densiflora)-Mongolian oak(Quercus mongolica), Hornb eam(Carpinus laxiflora)-Pitch pine(P. rigida), oriental oak(Q. variabilis) - a wild pear tree(Sorbus alnifolia) while the clustering of Mt. Daemo consisted of Pitch pine-Japanese larch(Larix leptolepis), Poplar(Populus tomentig landulosa)- black birch(Betula davurica pall). Meanwhile, the clustering of Mt. Bonghwa consisted of pine trees-a wild pear tree Community and Sawtooth oak(Q. acutissima)-Cherry Blossoms(Prunus serrulata). In relation to the similarity index by region in Mt. Bulam, Mt. Daemo, and Mt. Bonghwa, the similarity index of Mt. Bulam and Mt. Daemo stood at as high as 0.634, suggesting the distribution of similar vegetation, and the dominance index of the Mt. Daemo region was found to be 0.166 which suggests the dominance of many species compared to other regions. In addition, the results of species diversity showed that Mt. Daemo had the highest stability, and the species diversity, maximum species diversity, evenness indices were highest in Mt. Bulam, followed by Mt. Bonghwa and Mt. Daemo. The dominance index was the lowest in Mt. Bulam, followed by Mt. Bonghwa and Mt. Daemo.

• Journal of Bio-Environment Control
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• v.33 no.2
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• pp.107-113
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• 2024

For efficient soil water management in open fields, the proper use of soil moisture sensors is a prerequisite. Particularly in open-field environments like orchards with extensive root systems, the appropriate positioning of sensors is very important. The present study was conducted to identify the optimal placement of soil moisture sensors by assessing changes in soil water potential across various positions within orchard field soils after installing tensiometers. In apple and Asian pear orchards located in two regions of Korea, nine soil water potential sensors (TEROS 21, METER Group) were installed at distances of 20, 40, and 60 cm from the tree trunk and depths of 10, 20, and 30 cm from the soil surface, and monitored the soil water potential changes over two years. Results indicated that the positions closer to the tree trunk and the soil surface exhibited more pronounced changes in soil water potential. The greatest magnitude of change in soil water potential was observed at a distance of 20 cm and a depth of 10 cm, suggesting this position as the most suitable for soil moisture sensor installation. However, variations in the degree and pattern of changes in soil water potential were noted across sensor positions due to root system growth over time. Therefore, periodic observation and adjustments in sensor placement would be advisable to accurately monitor the soil moisture condition in long-term crops such as fruit trees in open fields.

• Korean Journal of Environment and Ecology
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• v.16 no.2
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• pp.160-171
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• 2002

In order to clarify the species composition, distribution and habitat of the Korean wild Pyrus ussuriensis and P. pyrifolia communities, that are so expected as a useful resource plant, an investigation was carried out according to phytosociological method on Mts. Hambaek, Ilwol, Sobaek, Juwang and Gaya in Korea. In the present study, we made an attempt to elucidate the autecological characteristics of the wild Pyrus species by synecological approach. As a result, the forests including the Pyrus species were divided into the two associations and two communities, considering the existing vegetation units for the forest; Syneilesio-Quercetum serratae, Corylo-Quercetum mongozicae, Ainsziaea acerifolia- Quercus mongolica community and Fraxinus rhynchophylla-Pyrus ussuriensis community. Among the units, the Syneilesio-Quercetum serratae and the Corylo-Quercetum mongolicae belong to southern type and middile-northern type, respectively, in their distributional type. It is inferred that the wild Pyrus species are distributed preferably in the deciduous forest zone in Korea, compared to the other forest zones. In particular the Pyrus species are present alone or dominantly in only both the tree layer or subtree layer of the forests, reflecting their shade intolerance ecophysiologically. Thus they usually were distributed in SE or SW of slope aspect. Generally the canopy of the forests including the Pyrus species was so open. Species diversity of the vegetation units was highest in the Syneizesio-Quercetum serratae and lowest in the Ainsliaea acerifolia-Quercus mongolica community. The Corylo-Quercetum mongolicae and the Pyrus ussuriensis-Fraxinus rhynchophylla community are medium between the two.

• Horticultural Science & Technology
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• v.17 no.4
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• pp.476-480
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• 1999

This study was carried out to determine the optimum storage temperatures of six fruit nurseries ('Fuji' apple, 'Niitaka' pear, 'Sheridan' grape, 'Yumyoung' peach, 'Fuyu' persimmon, and 'Hayward' kiwifruit) from 1995 to 1997. Nursery plants were planted in field after storage at -5, 0, and $5^{\circ}C$ for one year. Nurseries stored at $0^{\circ}C$ showed highest survival rate and growth after planting. The survival rate of 'Sheridan' grape and 'Hayward' kiwifruit nursery plants stored at $-5^{\circ}C$ was 0%. Cold resistance of the two fruit nursery plants appeared weaker than others. Also, 'Niitaka' pear nursery plants stored at $5^{\circ}C$ showed significantly high survival rate and growth after planting. The higher storage temperature, the lower mineral and carbohydrate contents of nursery plants. Therefore, $0{\sim}5^{\circ}C$ in 'Niitaka' pear and near $0^{\circ}C$ in other five fruit nursery stocks were found to be the optimum storage temperatures.

• Korean Journal of Organic Agriculture
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• v.18 no.3
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• pp.363-375
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• 2010

Sustainable farming systems have remarkably increased in Korea due to the increase of environmental concerns caused by the conventional systems. This study was performed on eight-year-old 'Niitaka' pear tree s to investigate the effects of different organic fertilizers on soil chemical and microbial properties and leaf and bud developments. Treatment and applications included 10 kg of rice bran (RB), 10 kg of coffee bran compost (CBC), 10 kg of Chitin incubated compost (Micro keeper$keeper^{(R)}$, CIC), and 30 kg of the mixture of the RB, CBC, and CIC (RCC). Control received 60 g of NPK (16-11-12) chemical fertilizer. The organic fertilizers increased organic matter, nutrient concentrations such as P, K, Ca, and Mg, and microbial biomass in soils compared to the control. RCC had the greatest specific leaf weight (SLW), and the other treatments did not have a significant difference for the SL W. Leaf P and K concentrations were different among the treatments, but they were not affected by the amounts of the soil nutrients. No differences were observed in the leaf Ca and Mg concentrations in the treatments. Organic fertilizers had greater chlorophyll contents than the control but had similar flower bud characteristics to the control.

• Korean Journal of Plant Resources
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• v.36 no.1
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• pp.100-106
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• 2023

In order to control the fire blight disease, all plants within the radius of the diseased orchard were removed in the early stage of the outbreak, or antibiotics control was performed for prevention. Since the beginning of antibiotics use on plants, the potential for development of resistance to antibiotics by the plant pathogen and unintended detrimental effects on the fruit trees and environment has become a problem. The purpose of this study is to determine the degree of phytotoxicity to fruit trees caused by excessive spraying of the fire blight disease disinfectant and to establish basic data for safe disinfectant guide. We analyzed whether damage to the fruit tree and the maximum residual limit of fruit was exceeded when three kinds of the fire blight disease disinfectants were continuously sprayed in excess of the number of safe use during the growing season. There was no phytotoxicity in apple 'Fuji' and pear 'Niitaka', and oxolinic acid was detected beyond the limit of quantitation in 'Fuji' grown without a bag, and the other disinfectants were detected below the maximum residue limit. When these disinfectants are continuously sprayed in excess of the number of safe, phytotoxicity may remain on the fruit. Therefore, it is necessary to observe the prescribed dilution factor and observe the safe frequency and the timing of use.

• Research in Plant Disease
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• v.29 no.1
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• pp.79-81
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• 2023

During the nationwide survey of fire blight, the typical shoot blight symptoms were found on Korean mountain ash (Sorbus alnifolia) which was located near an orchard that produced fire blight on pear trees in Eumseong, Korea, May 2021. To identify the causal agent, we progressed isolation from the symptomatic leaves and shoots. Two white and mucoid colonies were isolated into the pure culture. Two isolates were identified as Erwinia amylovora according to the colony-polymerase chain reaction (PCR) with amsB primers and the phylogenetic tree using 16S rRNA sequences. To test of pathogenicity of two isolates, we inoculated immature pear fruits and understock of apple. We observed necrosis and oozes on immature pear fruits and shoot blight resulting in necrosis on apple shoots six days after inoculation. Colonies were recovered from the inoculated pears and apples, and identity was confirmed through colony PCR for amsB genes. To our knowledge, E. amylovora was first reported on Korean mountain ash native to South Korea.