• The Plant Pathology Journal
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• 제39권4호
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• pp.397-408
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• 2023

Fire blight disease, caused by Erwinia amylovora, is a devastating affliction in apple cultivation worldwide. Chemical pesticides have exhibited limited effectiveness in controlling the disease, and biological control options for treating fruit trees are limited. Therefore, a relatively large-scale survey is necessary to develop microbial agents for apple trees. Here we collected healthy apple trees from across the country to identify common and core bacterial taxa. We analyzed the endophytic bacterial communities in leaves and twigs and discovered that the twig bacterial communities were more conserved than those in the leaves, regardless of the origin of the sample. This finding indicates that specific endophytic taxa are consistently present in healthy apple trees and may be involved in vital functions such as disease prevention and growth. Furthermore, we compared the community metabolite pathway expression rates of these endophyte communities with those of E. amylovora infected apple trees and discovered that the endophyte communities in healthy apple trees not only had similar community structures but also similar metabolite pathway expression rates. Additionally, Pseudomonas and Methylobacterium-Methylorobrum were the dominant taxa in all healthy apple trees. Our findings provide valuable insights into the potential roles of endophytes in healthy apple trees and inform the development of strategies for enhancing apple growth and resilience. Moreover, the similarity in cluster structure and pathway analysis between healthy orchards was mutually reinforcing, demonstrating the power of microbiome analysis as a tool for identifying factors that contribute to plant health.

• The Plant Pathology Journal
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• 제39권6호
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• pp.538-547
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• 2023

Rapid apple decline (RAD) is a complex phenomenon affecting cultivated apple trees and particularly dwarf rootstocks on grafted young apple trees. Since its first appearance in the United States, RAD has been reported worldwide, for example in Canada, South America, Africa, and Asia. The phenomenon has also been observed in apple orchards in Korea, and it presented similar symptoms regardless of apple cultivar and cultivation period. Most previous reports have suggested that RAD may be associated with multiple factors, including plant pathogenic infections, abiotic stresses, environmental conditions, and the susceptibility of trees to cold injury during winter. However, RAD was observed to be more severe and affect more frequently apple trees on the Malling series dwarf rootstock. In this study, we reviewed the current status of RAD worldwide and surveyed biotic and abiotic factors that are potentially closely related to it in Korea.

• 식물병연구
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• 제26권2호
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• pp.88-94
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• 2020

Recently, the severe dieback of apple trees resulting from soil-borne diseases has occurred in South Korea. The casual agents of dieback were surveyed on 74 apple orchards that had been damaged nationwide in 2016-2019. The number of apple orchards affected alone by Phytophthora rot, violet root rot, and white root rot was 31, 34, and 3, respectively. Also, the total number of mixed infection orchards was 6. Out of 9,112 apple trees affected by dieback, the trees damaged by Phytophthora rot, violet root rot, and white root rot were 3,332, 3,831, and 44, respectively. Moreover, the total number of mixed infection apple trees was 1,905. The provinces mainly affected were Gyeongnam, Gyeongbuk, Chungbuk, and Jeonbuk. The survey on these infected apple orchards will be available to form management strategy for the dieback that had been increased by soil-borne fungal pathogens.

• 한국환경농학회지
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• 제42권4호
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• pp.297-310
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• 2023

M.7 rootstock is moderately resistant to fire blight. However, M.7 is generally too vigorous for high-density apple systems, but it can be grafted onto cultivars that exhibit weak tree growth, such as 'Sansa'. This study investigated the vegetative growth, yield, and fruit quality of 'Sansa' apple trees grafted on M.7 or M.9 rootstocks to assess the feasibility of establishing domestic high-density apple systems using M.7 and to determine the optimum exposure length for rootstocks. Trees were planted with exposed rootstock lengths of 5, 10, and 15 cm. The vegetative growth of apple trees grafted onto M.7 was greater than that of M.9 and vegetative growth tended to decrease as the exposed length of rootstock increased. However, the differences in yield per tree, average weights, soluble solids contents, and titratable acidity due to the rootstock and its exposure length varied. The accumulated yield over a 10 year period and the yield efficiency of M.7 were lower than that of M.9 and the yield efficiency tended to decrease as the exposed length of rootstock increased. When apple trees were grafted onto M.9, biennial bearing and tree vigor weakening occurred if the exposed length of the rootstock was over 10 cm. Conversely, when apple trees were grafted onto M.7, vegetative growth was excessive if the exposed length of rootstock was below 10 cm. Based on the results from this study, the optimum M.7 and M.9 exposure lengths for 'Sansa' were 15 cm and 5 cm, respectively.

• IEIE Transactions on Smart Processing and Computing
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• 제4권4호
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• pp.265-271
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• 2015

This study proposes an algorithm for recognizing apple trees in images and detecting apples to measure the number of apples on the trees. The proposed algorithm explores whether there are apple trees or not based on the number of image block-unit edges, and then it detects apple areas. In order to extract colors appropriate for apple areas, the CIE $L^*a^*b^*$ color space is used. In order to extract apple characteristics strong against illumination changes, modified census transform (MCT) is used. Then, using the AdaBoost learning algorithm, characteristics data on the apples are learned and generated. With the generated data, the detection of apple areas is made. The proposed algorithm has a higher detection rate than existing pixel-based image processing algorithms and minimizes false detection.

• Journal of the Optical Society of Korea
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• 제16권2호
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• pp.133-140
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• 2012

In this study we investigate the use of 2D and 3D scanning optical coherence tomography (OCT) technology for use in apple blotch diagnosis. In order to test the possible application of OCT as a detection tool for apple trees affected by Marssonina coronaria, we conducted several experiments and compared the results from both healthy and infected leaves. Using OCT, we found several distinctive features in the subsurface boundary regions of both the diseased and healthy leaves. Our results indicate that leaves from diseased trees, while still appearing healthy, can be affected by M. coronaria. The A-scan analysis method confirmed that the boundaries found under the subsurface layers can be faint. This shows that M. coronaria can exert its influence on entire apple trees (as opposed to only on leaves with lesions) once it infects healthy trees. Our results indicate that OCT can be used as a noninvasive tool for the diagnosis of fungal disease in apple trees. Microscopic imaging results, performed as a histological study for comparison, correlated well with the OCT results.

• 한국응용곤충학회지
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• 제34권3호
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• pp.256-265
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• 1995

사과원 잡초군락이 해충 및 천적발생에 미치는 영향을 알아보기 위하여 제초제를 살포하여 잡초를 제거한 구(제초구)와 수관하부까지 잡초를 키우면서 인력으로예초한 구(예초구)에서 수상의 해충 및 천적과 잡초상의 곤충류를 조사하여 다음과 같은 결과를 얻었다. 응애류와 진딧물의 발생은 처리간에 유의성있는 차이는 없었으나, 응애류의 경우는 예초구에서 발생이 적은 경향이었다. 사과굴나방의 경우 예초구에서 1993년에는 피해엽률이 10% 정도 낮았고, 1994년은 4% 정도 낮은 발생을 보였다. 응애류와 진딧물의 천적류 발생은 쳬초구에서 높은 경향이었으나 큰 차이는 없었으며 사과굴나방의 기생청 천적류는 예초구에서 1993년에는 6~10%, 1994년에는 20~25% 높은 발생을 보였다. 사과원 잡초상에서 포충망을 이용 곤충류를 채집 조사한 결과, 사과해충은 발견되지 않았으며, 사과해충 천적류로서 좀벌류, 고치벌류, 애꽃노리재, 무당벌류, 풀잠자리류 등이 발견되었다. 사과생육기간중 잡초상 및 수상에서 군충군집변화는 상이하였다. 수상에서의 곤충군집형성에 약제살포가 큰 영향을 주었으나, 잡초상에서는 약제살포에 상대적으로 안정된 군집이 유지되었다. 결론적으로 사과원 잡초는 수상의 사과해충 및 천적발생에 영향을 주고 있었으며, 사과굴나방 기생벌같은 기주특이적인 천적들은 수상이동에 의하여 밀도억제작용을 하였고, 잡초상에 먹이가 풍부하거나 또는 광식성인 천적들은 잡초상 곤충군집에 연관되어 수상의 해충밀도에 큰 영향을 주지 못했다.

• 식물병과 농업
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• 제5권1호
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• pp.46-49
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• 1999

Bacterial blight occurred on the flowers, leaves, twigs and branches of apple trees (Malus domestica Borkh) in Chunchon, Kangwon-Do. Infected flowers and leaves turned brownish black, and they were fallen down or remained hanging in the trees. Under humid conditions during postblossom period, the casual bacterium spreaded along twigs and killed them. However, killing of branches was very rare. The symptoms on apple trees were very similar to symptoms of fire blight. But the causal organism isolated from the lesions was identified as Pseudomonas syringae based on physiological and chemical characteristics. This is the first described bacterium that causes apple shoot blight in Korea.

• 농촌지도와개발
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• 제4권2호
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• pp.423-429
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• 1997

Under the WTO system in the world, our country's apple industry must be set in quite a new aspect. For new apple industry with competition power, we should establish apple industry development strategies as follows. First, to change the present apple trees to the lowered or dwarf tree with high density planting system using M9 rootstocks. Second, to expand the size of apple orchard management and to bring up as professional apple farmers. Third, to develop the integrated apple production system considering environment and human being. Fourth, to innovate improved harvest, storage and shipment system. Finally, Rural Extension Institution should activate the farmer's training and produce the apple nursery trees of better quality.

• 한국유기농업학회지
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• 제19권spc호
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• pp.165-168
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• 2011

An organic apple (Malus ${\times}$ domestics Borkh.) orchard was established to study the interaction effects of ground cover management systems (GMS) and nutrient sources (NS) on soil and tree nutrient status and tree growth. Trees received one of four GMS: 1) green compost (GC), 2) wood chips (WC), 3) shredded paper (SP), and 4) mow-and-blow (MB). Across all GMS, one of three NS was applied: A) a commercial organic fertilizer (CF), B) poultry litter (PL), and C) control (NF). Overall, GMS had greater effects on the variables than did NS. GC mulch supplied greater nutrients, followed by WC, SP, and MB mulches. SP trees had lower foliar [N] in the first two years than the GC and WC trees. GC-and WC-treated trees had larger trunk cross sectional area than the SP and MB trees.