Soft Rot on Citrus unshiu Caused by Rhizopus oryzae in Korea

Rhizopus oryzae에 의한 감귤 무름병

  • Kwon, Jin-Hyeuk (Gyeongsangnam-do Agricultural Research and Extension Servies) ;
  • Kim, Jin-Woo (Institute of Agriculture and Life Science, Gyeongsang National University) ;
  • Hyun, Jae-Wook (Citrus Research Station, National Institute of Horticultural and Herbal Science, RDA) ;
  • Lee, Yong-Hwan (Knowledge and Information Officer Division, RDA) ;
  • Shim, Hong-Sik (National Academy of Agricultural Science, RDA)
  • Received : 2011.02.21
  • Accepted : 2011.03.17
  • Published : 2011.04.30


Soft rot caused by Rhizopus oryzae occurred on unshiu orange (Citrus unshiu Marc.) sampled from commercial markets in Jinju, Korea, 2010. The first symptom of soft rot on orange is a water-soaked appearance of the affected tissue. The infected parts later disintegrated into a mushy mass of disorganized cells followed by rapid softening of the diseased tissue. The lesion on orange was rapidly softened and rotted, then became brown or dark brown. Optimum temperature for mycelial growth of the causal fungus on potato dextrose agar was $30^{\circ}C$ and growth was still apparent at $37^{\circ}C$. Sporangiophores were $6{\sim}20\;{\mu}m$ in diameter. Sporangia were globose and $40{\sim}200\;{\mu}m$ in size. The color of sporangia was brownish-grey to blackish-grey at maturity. Sporangiospores were sub-globose, brownish- black streaked and $4{\sim}10\;{\mu}m$ in size. Columella were globose to sub-globose and $85{\sim}120\;{\mu}m$ in size. On the basis of mycological characteristics, pathogenicity test, and the ITS sequence analysis, the causal fungus was identified as Rhizopus oryzae. To our knowledge, this is the first report of soft rot caused by R. oryzae on unshiu orange in Korea.


Grant : Cooperative Research Program for Agriculture Science & Technology Development

Supported by : Rural Development Administration


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