Cupped, distorted and upright leaves showing the confluent scabby lesions along veins and petioles (J. O'Sullivan).

Brown, raised corky lesions on leaf (E. T. Rasco).

Diagnostic summary

• What you see on plants

- first evident symptoms are small  yellowish to reddish brown spots on the leaves. As the disease advances, spots become corky outgrowth. Lesions merge and the whole affected tissue develops a scabby appearance.

- leaf veins are mostly infected. Affected portions stop growing, so the leaves curl and become contorted or twisted.

- lesions on stems may be circular, elongate or flat, depressed or slightly raised and brownish. Sometimes the borders are distinctly water-soaked. The lesions become rough and scab-like and can also coalesce to form larger lesions.

- young shoots become contorted and twisted. Badly affected plant parts dry out and die.

• Transmitted by infected cuttings, rain splash, mist and dew or sprinkle irrigation.

• Most severe fungal disease of sweetpotato in South East Asia and the Pacific.

• Similar symptoms on the leaves are also caused by the thrips Dendrothripoides innoxius.

Taxonomy

Economic Importance

Geographical distribution

Symptoms

Morphology

Biology and ecology

Host range

Management

References

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