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Suppression of Melanose Caused by Diaporthe citri on Citrus Leaves Pretreated with Bio-sulfur
Plant Pathol. J. 2019;35:417-424
Published online October 1, 2019
© 2019 The Korean Society of Plant Pathology.

Yong Ho Shin1, Eun Ju Ko1, Su Jeong Kim2, He Nam Hyun1,3, and Yong Chull Jeun1,3,4*

1College of Applied Life Science, Major of Plant Resources & Environment, Jeju National University, Jeju 63243, Korea
2Postech Biotech Center, Pohang University of Science and Technology, Pohang 37673, Korea
3Sustainable Agriculture Research Institute, Jeju National University, Jeju 63243, Korea
4The Research Institute for Subtropical Agriculture and Biotechnology, Jeju National University, Jeju 63604, Korea
Correspondence to: Phone) +82-64-754-3319, FAX) +82-64-725-2351
Yong Chull Jeun

Handling Editor : Kim, Ki Woo
Received April 17, 2019; Revised May 29, 2019; Accepted June 19, 2019.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Melanose, caused by Diaporthe citri, is one of severe diseases in citrus, a major economic resource in Jeju island. To reduce the usage amount of organic synthetic fungicide, bio-sulfur was tested as an alternative chemical to control citrus melanose in the present study. Direct antifungal activity of bio-sulfur against D. citri was determined through in vitro experiment using artificial nutrient media. Disease severity of melanose on bio-sulfur pretreated citrus leaves was lower than that on untreated ones. To illustrate the mechanism of disease suppression by bio-sulfur, infection structures were observed with a fluorescent microscope and a scanning electron microscope. In fluorescent microscopic observation, most conidia rarely germinated. In addition, hyphal growth on leaves pretreated with bio-sulfur was inhibited compared to that on untreated ones. In scanning electron microscope images of bio-sulfur pretreated leaves, surfaces of most conidia were shrunk while hyphae were morphologically changed and frequently branched. Such microscopic observations were also found for leaves pretreated with a commercial fungicide Dithianon. These results suggest that bio-sulfur may be used to control citrus melanose as an environment friendly alternative to organic synthetic fungicides
Keywords : environment friendly, fluorescence microscope, infection behavior, scanning electron microscope

October 2019, 35 (5)
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