• Research in Plant Disease
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• v.22 no.3
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• pp.168-177
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• 2016

A forecast model for estimating the infection risk of bacterial canker caused by Pseudomonas syringae pv. actinidiae on kiwifruit leaves in Korea was developed using the generic infection model of Magarey et al. (2005). Two-way contingency table analysis was carried out to evaluate accuracy of forecast models including the model developed in this study for estimating the infection of bacterial canker on kiwifruit using the weather and disease data collected from three kiwifruit orchards at Seogwipo in 2015. All the tested models had more than 80% of probability of detection indicating that all the tested models could be effective to manage the disease. The model developed in this study showed the highest values in proportion of correct (51.1%), probability of detection (90.9%), and critical success index (47.6%). It indicated that the model developed in this study would be the best model for estimating the infection of bacterial wilt on kiwifruit leaves in Korea. The model developed in this study could be used for a part of decision support system for managing bacterial wilt on kiwifruit leaves and help growers to reduce the loss caused by the disease in Korea.

• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.1
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• pp.27-33
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• 2020

To date, various kiwifruit cultivars have been developed and released. Asexual propagation by grafting onto seedlings rootstock have been widely utilized commercially in fruit trees including kiwifruit (Actinidia spp.). Most of commercial kiwifruit cultivars belong to A. chinensis and A. deliciosa. Recently, several cultivars were developed by interspecific hybridization with different species including A. arguta. There is a possibility for graft-incompatibility due to interspecific hybridization and therefore, we investigated graft-compatibility of newly released yellow-fleshed kiwifruit cultivars and a hybrid cultivar with various rootstocks of different species. The yellow-fleshed cultivars grafted onto same species, A. chinensis 'Kuimi', showed good shoot elongation, about 1 m in length 50 days after grafting. In contrast, the shoot elongation of the yellow-fleshed kiwifruit grafted onto different species was retarded. The shoot length of a hybrid cultivar (A. arguta × A. deliciosa) 'Skinny Green' grafted onto four different species was about 1 m in length, showing good graft compatibility with other species. Nevertheless, long term studies for graft compatibility of hybrid cultivars are still needed since graft-incompatibility between different species can occur several years later.

• The Plant Pathology Journal
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• v.19 no.5
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• pp.227-230
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• 2003

Ripe rot was commonly found in overripe kiwifruits (Actinidia deliciosa) during a disease survey conducted in Jeju and Jeonnam provinces in Korea in 1999. While the disease did not manifest any clear external symptoms on kiwifruits, it caused portion of the fruit surface to collapse. Watersoaked flesh tissue could be seen on the sunken part when the skin of the collapsed portion was peeled off. The milky internal symptom with dark green margin developed concentrically as the fruit ripened. A species of Botryosphaeria was consistently isolated from lesions showing typical symptoms of ripe rot on kiwifruit, and its pathogenicity was confirmed by artificial inoculation test on healthy kiwifruits. The fungus was also pathogenic to apple and pear. The mycological characteristics of the fungus were consistent with those of Botryosphaeria dothidea. This is the first report on the detailed mycological characteristics of the causal organism of post-harvest ripe rot of kiwifruit in Korea.

• Research in Plant Disease
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• v.27 no.1
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• pp.24-31
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• 2021

Since the past few years, dimple rot has become one of the most serious diseases affecting Actinidia chinensis var. chinensis 'Zesy002' kiwifruit in Korea, leading to a low quality and subsequent losses of income. In the current study, the causal pathogen of side rot on 'Zesy002' kiwifruit was identified to be Botryosphaeria dothidea, a widespread pathogen that could penetrate the fruit directly without wounding. Diaporthe sp., another pathogen causing dimple rot, was isolated from infected kiwifruit. It was not able to infect fruits without wounding. Dimple-rot symptoms are known to be associated with other pathogens from the Pseudocercospora genus. In this study, B. dothidea was ratified as the causal disease agent in Jeju Island. To illustrate the pathogenicity of this fungus on 'Zesy002', further studies such as observation of infection structures of fungus may be needed.

• The Plant Pathology Journal
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• v.39 no.3
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• pp.245-254
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• 2023

The plant microbiota plays a crucial role in promoting plant health by facilitating the nutrient acquisition, abiotic stress tolerance, biotic stress resilience, and host immune regulation. Despite decades of research efforts, the precise relationship and function between plants and microorganisms remain unclear. Kiwifruit (Actinidia spp.) is a widely cultivated horticultural crop known for its high vitamin C, potassium, and phytochemical content. In this study, we investigated the microbial communities of kiwifruit across different cultivars (cvs. Deliwoong and Sweetgold) and tissues at various developmental stages. Our results showed that the microbiota community similarity was confirmed between the cultivars using principal coordinates analysis. Network analysis using both degree and eigenvector centrality indicated similar network forms between the cultivars. Furthermore, Streptomycetaceae was identified in the endosphere of cv. Deliwoong by analyzing amplicon sequence variants corresponding to tissues with an eigenvector centrality value of 0.6 or higher. Our findings provide a foundation for maintaining kiwifruit health through the analysis of its microbial community.

• Research in Plant Disease
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• v.9 no.3
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• pp.170-173
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• 2003

For the effective chemical control to minimize infection of storage pathogens on kiwifruit in the field, this study was conducted to screen alternative fungicides which could be substituted for the fungicides Benomyl WP and Thiophanate-methyl 제 registered for the control of postharvest fruit rats of kiwifruit in Korea. Among the 8 fungicides tested, Tebuconazole WP, Iprodione WP and Flusilazole WP showed higher inhibitory effects on themycelial growths of 3 major pathogens of postharvest fruit rots, Botryosphaeria dothidea, Diaporthe actinidiae and Botrytis cinerea on potato dextrose agar. They also showed control efficiencies as high as those of Benomyl WP and Thiophanate-methyl WP on postharvest fruit rots in the field. They might be good candidates for fungicieds for the control of postharvest fruit rots of kiwifruit.

• Research in Plant Disease
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• v.10 no.4
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• pp.297-303
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• 2004

Bacterial blossom blight of kiwifruit (Actinidia deliciosa) has been mainly controlled by antibiotics. Among 15 candidate chemicals, streptomycin sulfate oxytetracycline WP, streptomycin copper hydroxide WP and oxolinic acid WP were selected as preventive bactericides against bacterial blossom blight of kiwfruit through in vitro and in vivo test. Spray of streptomycin sulfate oxytetracycline WP and streptomycin copper hydroxide WP at flowering period was most effective in controlling bacterial blossom blight of kiwifruit. Among the various combinations of spray times at different spray periods, optimum spray program of the preventive bactericides for the control of bacterial blossom blight of kiwifruit was turned out to be 3 times application with 10 day-interval from early May during the flowering season of kiwifruits.

• Horticultural Science & Technology
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• v.30 no.6
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• pp.709-717
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• 2012

To establish the standard of ripe kiwifruit sorting, near infrared (NIR) spectroscopy was performed on kiwifruit sampled from three farms. Destructive measurements of flesh firmness, soluble solids content (SSC), and acidity were performed and compared to measurement using NIR reflectance spectrums from 408 to 2,492 nm. NIR predictions of those quality factors were calculated using the modified partial least square regression method. Flesh firmness was predicted with a standard error of prediction (SEP) of 3.32 N and with a correlation coefficient ($R^2$) of 0.88. SSC was predicted with SEP of $0.49^{\circ}Brix$ and with $R^2$ of 0.98. Acidity was predicted with SEP of 0.28% and with $R^2$ of 0.91. Kiwifruit ripened at $20^{\circ}C$ for 15 days showed uneven qualities with normal distribution. Considering the SEP of each parameter, kiwifruit after ripening treatment could be non-destructively predicted their qualities and sorted by flesh firmness or soluble solids content through NIR prediction.

• Research in Plant Disease
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• v.26 no.1
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• pp.44-47
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• 2020

Streptomycin resistant isolates of Pseudomonas syringae pv. actinidiae, the causal agent of bacterial canker in kiwifruit, were found in Korea. A total of 734 isolates of P. syringae pv. actinidiae collected between 2008 and 2017 from bacterial canker infections in 111 kiwifruit orchards were assessed for streptomycin resistance. The survival of each isolate was screened against 100 ㎍/ml of streptomycin. Among 734 isolates, 38 streptomycin resistant P. syringae pv. actinidiae isolates originated from nine orchards were found. Streptomycin resistant isolates belonging to biovar 2 were found in several individual years, but ones belonging to biovar 3 were found in Korea only since 2016. Therefore, to use streptomycin for control of bacterial canker in kiwifruit orchards should be very careful, and it is necessary to check the streptomycin susceptibility of the pathogen before use in kiwifruit orchards.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.863-868
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• 1989

In comparison of contents of the components related to the quality of kiwifruit depended on the cultivars, the obtained results were as follows; Abbott showed the highest values in soluble solid, crude fat, firmness and specific gravity. Potassium, phosphorus, calcium and magnesium were estimated as the major minerals in kiwifruit and Bruno contained the highest amounts of potassium and magnesium. Bruno also had high concentrations of ascorbic, maleic, citric and fumaric acid when compared with the other cultivars. The changes in chemical components of kiwifruit (Hayward) by ripening stage were as follows; During ripening, the glucose and fructose contents were increased with decrease of sucrose content. Ascorbic, maleic, fumaric and succinic acid contents were considerably increased during ripening From the investigation of changes in protein pattern by electrophoresis! the new bands with about 17,000-23,50kd were shown during ripening.