• The Plant Pathology Journal
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• v.37 no.6
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• pp.681-686
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• 2021

It is difficult to distinguish melanose and melanoses-like symptoms with the naked eye because they appear similar. To accurately detect melanose symptoms caused by Diaporthe citri from melanose-like symptoms, we developed PCR-based specific primers Dcitri by aligning the internal transcribed spacer (ITS) region of D. citri with the ITS of Diaporthe cytosporella, Diaporthe foeniculina, Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria citri, and Fusarium oxysporum found on citrus peel. PCR results showed that the specific product was amplified in D. citri but not in other isolates including, C. gloeosporioides, B. cinerea, A. citri, F. oxysporum. In addition, specific products were observed in melanose symptoms caused by D. citri but not in melanose-like symptoms, such as copper-injury, sunscald, damages by yellow tea thrips, and pink citrus rust mite. Using the Dcitri primers developed in this study, it is expected that melanose caused by D. citri could be accurately distinguished from melanose-like symptoms.

• The Plant Pathology Journal
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• v.23 no.4
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• pp.308-313
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• 2007

A survey of the occurrence of abiotic diseases on kiwifruit (Actinidia deliciosa) trees was conducted at sixty-two kiwifruit orchards in twenty-one locations of Jeonnam and Jeju Provinces in Korea during the 2007 growing season. Various kinds of abiotic diseases were detected on the kiwifruit trees. Malformed fruits caused by incomplete pollination were commonly observed among the normally growing fruits on almost all of the kiwifruit trees examined. Fruits imbued with wire rust, fruits scratched or girdled by the wire and fruits injured by sunscald occurred in all of the examined orchards. Abnormal growth of girdled branches by the fence wire, dead trees killed by excessive soil moisture due to poor draining and leaf chlorosis by nutrient deficiencies were found in some orchards. Leaf spotting by herbicide and leaf scorch or blight by excessively high temperature were observed. Leaf blight on young shoots by late frost and bark split on trunks by freeze occurred in several open-field orchards. Flooding and strong wind damages by attack of typhoon 'Nari' were also found during the survey period. Cup-shaped leaves frequently occurred on young shoots in early spring and the incidence of the syndrome tends to increase annually in recent years, which are not etiologically defined until now.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.261-269
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• 2022

This study was carried out to predict fruit surface temperature (FST) causing sunburn symptoms and assess the correlation between solar radiation and FST in satusma mandarin (Citrus unshiu Marc. 'Iwasaki'). And to reduce sunburn when ambient temperature was at 31℃, sprinkler system was repeated spraying every at 5 minutes of 30 minutes intervals and 1% calcium carbonate and 4% kaolin solution applied on citrus tree three times to investigate quality and sunburn of fruits. It showed highly significant positive correlation between FST and solar radiation (R = 0.788, p < 0.01), The FST increased up to 16℃ than ambient temperature at daytime. To estimate FST, a linear model y = 0.099 × (air temperature) + 0.018 × (solar radiation) + 20.779 (R = 0.687, p < 0.01) was derived. The canopy temperature of citrus trees was 5.1℃ lower in sprinkler system than in control. The incidence of sunburn showed at 2.1% in sprinkler system twice lower than in control and there was different significance. Fruit quality was similar between treatments. In conclusion, sunburn can be reduced by reflecting sunlight or downing of FST through sprinkler system.