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First Report of Black Rot Caused by Diplodia seriata on Apple
Res. Plant Dis. 2018;24:321-327
Published online December 31, 2018
© 2018 The Korean Society of Plant Pathology.

Young Soo Kim, Yun Joo Yun, and Yongho Jeon*

Department of Plant Medicals, Andong National University, Andong 36729, Korea
*Tel: +82-54-820-5507 Fax: +82-540-820-6320 E-mail: yongbac@andong.ac.kr
Received September 20, 2018; Revised October 23, 2018; Accepted October 29, 2018.
cc This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
In 2018, symptoms of black rot on apple (Malus pumila var. dulcissima KOIDZ) cv. Fuji were observed in Yeongcheon-si, Korea. The fruit decay symptoms consisted of purple pimples spots, black rot around the seed cavity (calyx end), mummified fruit. To isolate the causal agent, small fragment (2 to 3 mm) of decayed tissue from the lesion margin were placed on WA or PDA. Fungal colonies on PDA produced dense white aerial mycelium, becoming dark gray with age. Pycnidia and conidia were observed under a light microscopy. The shapes of conidia were aseptate, ovoid, rounded at both ends, and 21.7-28.3 × 9.9-15.3 um. Based on morphological and cultural characteristics, this fungus was identified as Diplodia seriata. To confirm its identity, two loci (ITS and β-tubulin) were sequenced for molecular identification. BLAST searches indicated 100% identity with D. seriata. A pathogenicity test was conducted with isolates on Fuji apples. The apples were inoculated with mycelial plugs (5 mm) from 7-day-old cultures of the putative pathogens. All inoculated apples developed rot symptoms identical to the original symptoms, from which D. seriata were reisolated, fulfilling Koch’s postulates. This study is the first report of black rot caused Diplodia seriata on apple.
Keywords : Apple, Apple disease, Black rot, Diplodia seriata, ITS


December 2018, 24 (4)