Pacific Pests, Pathogens & Weeds - Fact Sheets

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Sweetpotato leaf spot (208)

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Photo 1. Sweetpotato leaves with leaf spots caused by Pseudocercospora timorensis.

Photo 2. Older leaf of sweetpotato with spots caused by Pseudocercospora timorensis.

Common Name

Sweetpotato leaf spot

Scientific Name

Pseudocercospora timorensis

Distribution

Widespread. Asia, Africa, the Caribbean, Oceania. It is recorded from American Samoa, Federated States of Micronesia, Fiji, Kiribati, Palau, Papua New Guinea, Samoa, Solomon Islands, Tonga, Vanuatu.

Hosts

Sweetpotato, and other Ipomoea species.

Symptoms & Life Cycle

Leaf spots are brown, circular to irregular on the upper surface, sometimes with light brown centres (Photos 1&2). As the spots grow, some join together. On the lower surface, the spots are brown or grey, but their shape is not well defined. Usually, the spots occur on mature leaves.

The spores occur mostly on the spots on the underside of the leaf, and are spread by wind.

Impact

The fungus that causes the leaf spots mainly damages old leaves, so it is unlikely that it causes a disease of economic importance.

Detection & inspection

Look for the brown circular to irregular spots on the older leaves, some joining together.

Management

The leaf spots are usually on the older leaves, so it is unlikely that they cause a disease of economic importance by reducing storage root yields. Therefore, control measures are not considered necessary. If they are, test the tolerance of different varieties.

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