Pacific Pests, Pathogens & Weeds - Fact Sheets

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Kangkong leaf spot (206)

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Photo 1. Leaf spot on kangkong (Ipomoea aquatica) caused by Cercospora ipomoeae.

Common Name

Kangkong leaf spot

Scientific Name

Cercospora ipomoeae

Distribution

Widespread. In the tropics. It is recorded from beach morning-glory (Ipomoea pes-caprae) from American Samoa, Cook Islands, Fiji, Kiribati, Guam, Samoa, and Solomon Islands. It it recorded from kangkong (Ipomoeae aquatica) from French Polynesi and Palau,

Hosts

Ipomoea aqutica, and common on Ipomoeae pes-caprae ssp. brasiliensis (a morning glory common on the sea shore). Other hosts are sweetpotato (reported from India), and species of Convolvulus and Merremia.

Symptoms & Life Cycle

Circular to irregular leaf spots, up to 5 mm diameter, light brown with dark brown or black borders on the upper surface, grey on the lower surface, with yellow haloes (Photo 1). The centres of the spots sometimes fall out.

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

Impact

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

Detection & inspection

Look for small spots with dark margins and broad yellow haloes on the older leaves.

Management

It is unlikely that this disease is of economic importance, especially as the fungus infects the older leaves, and it is the younger ones that are used as a vegetable.

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