Author
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KAPOORIA, R - LUSAKA, ZAMBIA |
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Aime, Mary |
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Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/20/2005 Publication Date: 1/1/2005 Citation: Kapooria, R.G. Aime, M.C. 2005. First report of Olivea scitula on Vitex doniana in Zambia. Plant Disease 89:431. Interpretive Summary: Rust fungi cause diseases on a wide range of trees and crop plants throughout the world. Accurate knowledge about the distribution of these fungi is important for preventing the spread of the diseases they cause. In this research a rust fungus that occurs on a species of Vitex is newly detected in the African country of Zambia. Although known in three other countries in Africa, this rust has never before been reported from this country. Species of trees in the genus Vitex are grown throughout the world as ornamentals and as the source of wood and unusual chemicals some of which have medicinal properties. This research will be used by plant quarantine officials and plant pathologists to determine the spread of and resistance to the disease caused by this rust. Technical Abstract: Vitex doniana Sweet (Verbenaceae) is a semi-deciduous tree of up to 15m height, occurring in most Provinces of Zambia as well as from Senegal to the Sudan, Somalia, Angola, Botswana, and South Africa (1). Wood from V. doniana is used in buildings and in making boxes, interior fittings and furniture; fruits are rich in Vitamins A and B and used for making jam and wine; leaves are used as cattle feed, and other plant parts are used in traditional medicines; and the tree itself is a favourite for hanging bark beehives. In September 2004 V. doniana growing in a private establishment 20 km southeast of Lusaka were found bearing brown infections on the lower side of leaves. Subsequent examination identified the infection as that of a rust fungus, Olivea scitula Syd. The following description is based on the Zambian material. Uredinia only; sori hypophyllous, brown, round, at first distributed irregularly in the form of streaks in the interveinal areas; coalescing rapidly to form a continuous erumpent covering at the base, margin or the middle of the leaflet. Uredospores yellow-brown, verrucose, globose, triangular or oval, 20 - 25 x 20 µm, with densely filled oil globules; wall 2 - 2.5 µm thick. Paraphyses peripheral, incurved and basally united, 50-75 x 5-6.25 µm. The pathogen has been reported previously from Sierra Leone, Uganda, and Nigeria (2). This is the first record of Olivea in Zambia, and the first of O. scitula from Central Africa. |
