Fusarium surface and root rots

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Causal organisms: F. oxysporum and Fusarium solani

Cross section of storage root with symptoms of surface rot (left) and Fusarium root rot (right) (C. Clark, APS).
  Shrinking and drying of storage root with Fusarium surface rot (T. Ames).

Diagnostic summary

  • What you see on plants

Surface rot

- lesions on storage roots are circular, uniformly light to dark brown, dry and firm. Infection may start at the stem end or at wounds obtained before, during and after harvest.

- lesions may slowly extend to the cortical tissue but do not usually extend beyond the vascular ring. 

- surface of the storage root shrinks and the flesh underneath dries out.

- white mycelium outgrowth is sometimes observed,  after which the root becomes hard and mummified.

Root rot

- lesions are alternating light and dark brown concentric or overlapping rings.  They spread beyond the vascular layer and may rot the whole root. 

- in advanced stages, cavities develop inside the lesion which often have white mould in inner surfaces.

- Surface rot usually infects only those in storage and is not transmitted from the mother root to the sprouts.

- Fusarium root rot can transmitted from the mother root to the sprouts, causing stem lesions.


Economic importance

Geographical distribution




Host range





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Fusarium wilt