Kangkong leaf spot
Pacific Pests, Pathogens & Weeds
Kangkong leaf spot (206)
Cercospora ipomoeae; also recorded as Cercospora bataticola.
Unknown. It is recorded from American Samoa, Cook Islands, Fiji, Kiribati, Guam, Samoa, and Solomon Islands (on beach morning-glory, Ipomoea pes-caprae. It is also recorded from French Polynesia and Palau on kangkong, Ipomoeae aquatica.
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 wind or splashing rain.
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. Look for the characteristic pale-brown to whitish-grey centres of the spots as they age.
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
Information from O'Sullivan J et al. (undated) Sweetpotato DiagNotes: A diagnostic key and information tool for sweetpotato problems. (https://keys.lucidcentral.org/keys/sweetpotato/key/Sweetpotato%20Diagnotes/Media/Html/TheProblems/DiseasesFungal/CercosporaLeafSpot/Cercospora%20leaf%20spot.htm). Photo 1 Kohler F, et al. (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.