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.

Taxonomy

Economic importance

Geographical distribution

Symptoms

Morphology

Biology and ecology

Host range

Management

References

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