Abstract

Abstract A description is provided for Cercospora duddiae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Allium ascalonicum, A. cepa, A. fistulosum, A porrum, A. sativum . DISEASE: Leaf spot or withertip on onion and garlic. The symptoms vary on the different host species. On onion circular, chlorotic spots 3-5 mm diam. form mainly on the tip of the leaf, gradually decreasing in number towards the leaf base. The lesions at the leaf tip coalesce, forming a dry greyish-brown area, and in severe cases the entire leaf tip may be killed. The base of the leaf is mottled with brown necrotic leaf spots. Eventually the necrotic tissue may spread down the leaf surface, delimited by a narrow band (3 mm) of chlorotic tissue (Welles, 1923). Rarely does the disease cause much damage (Chupp & Sherf, 1960). GEOGRAPHICAL DISTRIBUTION: Africa: Mauritius, Nigeria, Sierra Leone, Somalia, Uganda; Asia: Borneo, Brunei, Burma, India, Indonesia, Oman, The Yemen; Australasia: Papua New Guinea; North America: West Indies (Barbados, Jamaica). TRANSMISSION: By air-borne or water-splash dispersed conidia, and by transportation with onion parts. The fungus is also reported to be seed borne (Chupp & Sherf, 1960).

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