Black rot

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Causal organism: Ceratocystis fimbriata Ellis & Halsted


Black sunken lesion on storage root of a purple-skinned cultivar (W. Martin, APS).


Storage roots with black rot lesions (W. Martin, APS).

Diagnostic summary

  • What you see on plants

- on storage roots, first symptoms are brown, slightly sunken spots not more than 0.5 cm in diameter.  Lesions become firm, dry and black and  can coalesce to cover the entire root.


- in the field plants are stunted and chlorotic due to cankers present in underground stem.  Chlorotic leaves drop.


- in seedbeds, infected sprouts develop black sunken necrotic lesions or cankers at the point of attachment to the mother root. Affected shoots are girdled at soil level.


- tissues in the rotten spots and their surroundings have bitter taste but fruity odour.

  • Called black rot because of its symptoms  on storage roots. But can also be serious on young sprouts and adult plants.

  • Found in different regions of the world.


Economic importance

Geographical distribution



Biology and ecology

Host range



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