Kangkong leaf spot
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,
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.
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.
The fungus that causes the leaf spots mainly damages old leaves, so it is unlikely that it is of economic importance.
Look for small spots with dark margins and broad yellow haloes on the older leaves.
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.
AUTHOR Grahame Jackson
Photo 1 Kohler F, Pellegrin F, Jackson G, McKenzie E (1997) Diseases of cultivated crops in Pacific Island countries. South Pacific Commission. Pirie Printers Pty Limited, Canberra, Australia.
Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.
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