Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Cassava bacterial blight (173)

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Photo 1. Leaves with angular spots caused by cassava bacterial blight, Xanthosoma axonopodis pv. manihotis, at first limited by the veins, later joining together to form large brown areas of decay, especially at the leaf tips.

Photo 2. Leaves wilting and falling down caused by cassava bacterial blight, Xanthosoma axonopodis pv. manihotis.

Photo 3. "Candle" appearance of cassava stems, caused by cassava bacterial blight, Xanthosoma axonopodis pv. manihotis. Leaves infected by the disease have fallen from the stems, the terminal shoot has blackened, and new leaves have developed lower down the stem.

Summary

• Worldwide distribution. In most cassava-growing countries. On cassava and relatives. A very important bacterial disease.
• Angular dark spots on leaves, with creamy ooze, bordered by veins; the spots expand, merge and form large rots. Bacteria inside the leaves travel to the stems blocking water flow; leaves wilt, die and fall.
• Spread in wind and rain, in cuttings and on tools.
• Cultural control: take cuttings only from healthy plantations; do not plant new plots next to old; 1-2-year crop rotation; clean tools after use (bleach); collect and burn trash after harvest; resistant varieties (see SPC CePaCT for those available).
• Chemical control: none recommended.

Common Name

Cassava bacterial blight

Scientific Name

Xanthomonas axonopodis pv. manihotis. Previously, it was known as Xanthomonas. campestris pv. manihotis, and in Palau is it recorded as Bacterium robici, a much older name.

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