• Korean Journal Plant Pathology
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• v.14 no.2
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• pp.171-176
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• 1998

Gentic diversity of 42 isolates of Phomopsis citri was analyzed with random amplified polymorphic DNA(RAPD) and fungicide resistance. RAPD profiles of genomic DNA of the isolates of P. citri and the degrees of their resistance to the fungicides mancozeb and propineb suggested the occurrence of genetic differentiation of P. citri distributed in Cheju. The isolates showed genetically diverse RAPD profiles according to the host species collected even from the same collection site and also according to the geographic origin collected even from the same host species. High levels of resistance to fungicides mancozeb and propineb were observed among the isolates of P. citri. However, there was no correlation between RAPD profiles of genomic DNA and levels of fungicide resistance of the isolates, suggesting that fungicide resistance of P. citri occurred irrespective of the host and geographic origin.

• Research in Plant Disease
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• v.9 no.3
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• pp.153-158
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• 2003

Mycological characteristics of Phomopsis citri isolates obtained from blighted twigs of citrus cultivation areas in Jeju island were all identified as Phomopsis citri known as the anamorph stage of Diaporthe citri. Pycnidia the isolates sized from 112.2 to 614.4${\mu}m$ (av. 328.8${\mu}m$) and shaped conical to lenticulata in black. Two types of phialospores, ${\alpha}$-and ${\beta}$-spores were observed from pycnidia. The ${\alpha}$-spores were hyaline, unicellula, fusiform to ellipsoidal and sized 4.7~8.7 1.9 ${\times}$ 3.5${\mu}m$ (av. 6.7 ${\times}$ 2.3 ${\mu}m$). The ${\beta}$-spores were hyaline, unicellula, filiform, curved and often strongly hooked and sized 13.2~27.1 ${\times}$ 0.8~1.6 ${\mu}m$ (av. 22.1 ${\times}$ 1.0 ${\mu}m$). All isolates grew well and produced abundant pycnidia and spore horns on PDA. In addition, all isolates showed strong pathogenicity to citrus fruit inducing melanose symptoms when artificially inoculated with the pycnidial spores.

• Food Science and Preservation
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• v.9 no.2
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• pp.131-136
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• 2002

Quality changes of satsuma mandarin (Citrus unshiu Marc. var. miyagawa) during storage by storage warehouse were investigated. Citrus were treated with 2000-folds diluted iminoctadime-triacetate solution and 1.5% chitosan with 0.5% CaCl$_2$ solution, and were at 30$\^{C}$ for 24 hr before storage. The citrus of about 12kg/26L plastic container were stored at room temperature, and at 4$\^{C}$ with 87% relative humidity. Decay ratio of citrus with precise temperature and humidity control were lower than the others during storage. Penicillium italicum Monilia candida Alternara citri, Mucor hiemalis, Phomopsis citri Botrytis cinerea, Phoma citricarpa Clomererella cingulata, Penicillium digitatum were identified as putrefactive microorganisms in citrus storage. Weight loss, moisture content of peel and flesh were decreased slowly during storage. 24% of original acid content were decreased at room temperature on 120 days storage, compared to 15∼18% loss on cold storage. Total sugar of citrus was decreased rapidly after 90 days, and vitamin C content were also decreased rapidly after 60 days during storage.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1142-1145
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• 1996

Long term-storage of citrus oranges after harvest has been hindered mainly by molds The goal of this research was to collect and identify those molds, which would help find a way to extend shelf-life after harvest. During the period of 1994 to 1995, fourteen different strains were isolated and purified from putrefied fruit (Citrus unshiu var.) that was stored at room temperature under open air. The storage disease was caused by the following molds: Penicillium italicum, 25.8%, Monilia candida, 19.8%; Alternaria citri, 18.1%; Mucor hiemalis, 11.0%; Phomopsis citri, 6.6%; Botrytis cinerea. 5.5%; Phoma citricarpa, 3.8%; Glomerella cingulata, 3.8%; P. digitatum, 1.1%; other molds, 4.5%; Most of the strains showed pectinolytic activity and putrefaction. These citrus fruit-putrefying molds will be used as target strains for the control of microorganisms during post-harvest storage.

• The Plant Pathology Journal
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• v.31 no.3
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• pp.290-298
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• 2015

Starting in 2012, severe diebacks usually accompanied by abundant gum exudation have occurred on yuzu trees in Goheung-gun, Jeonnam Province, where severely affected trees were occasionally killed. On-farm surveys were conducted at 30 randomly-selected orchards located at Pungyang-myeon, Goheung-gun, and the resulting disease incidences were 18.5% and 39.6% for dieback and gumming symptoms, respectively. Black spots on branches and leaves also appeared on infected trees showing a typical dieback symptom. Morphological and molecular identifications of the isolated fungal organisms from lesions on the symptomatic leaves and branches revealed that they are identical to Phomopsis citri, known to cause gummosis. In order to find the reason for this sudden epidemic, we investigated the weather conditions that are exclusively distinct from previous years, hypothesizing that certain weather extremes might have caused the severe induction of pre-existing disease for yuzu. There were two extreme temperature drops beyond the yuzu's cold hardiness limit right after an abnormally-warm-temperature-rise during the winter of 2011-12, which could cause severe frost damage resulting in mechanical injuries and physiological weakness to the affected trees. Furthermore, there was an increased frequency of strong wind events, seven times in 2012 compared to only a few times in the previous years, that could also lead to extensive injuries on branches. In conclusion, we estimated that the possible damages by severe frost and frequent strong wind events during 2012 could cause the yuzu trees to be vulnerable to subsequent fungal infection by providing physical entries and increasing plant susceptibility to infections.