Rhizopus soft rot

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Causal organism: Rhizopus stolonifer (Ehrenb. ex Fr.) Lind.


Web-like outgrowth on storage root (W. Martin, APS).



  • Emits a pleasant fermented odour that attracts fruit flies.

  • Exposure of storage roots to sunlight and chilling can initiate the disease.

  • Infection takes place in a wide temperature range of 20 to 30C.

  • Found in different regions of the world.

Diagnostic summary

  • What you see on plants

water-soaked lesions develop after storage root has been wounded or bruised during harvest or handling.


lesions become covered by a web-like outgrowth with scattered pinhead-like structures.


entire inner tissues of the root rot become soft, slimy and watery as they liquefy. However, periderm remains almost intact except for small cracks and wrinkled appearance.


black brush-like domes with whisker-like appearance emerge from periderm cracks.

  • Rotting usually starts at both ends from wounds during harvest but any bruise or a slight scratch can initiate rotting.

  • Like bacterial rot, it produces a watery, flesh decaying rot. 


Economic importance

Geographical distribution



Biology and ecology

Host range




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