DisplayTitle

First Report of the Rust Fungus Olivea scitula on Vitex doniana in Zambia

Vitex doniana Sweet (Verbenaceae) is a semideciduous tree that occurs throughtout Africa from Senegal to the Sudan and in Somalia, Angola, Botswana, South Africa, and most provinces of Zambia. Wood from V. doniana is used in construction, making boxes and furniture; jam and wine are made from the vitamin-rich fruits; the leaves provide cattle feed; and other plant parts are used in traditional medicines. The tree itself is a favorite for hanging bark beehives. In September 2004, leaves of V. doniana trees (20 km southeast of Lusaka) were found bearing brown uredinia, which were subsequently identified as the rust fungus, Olivea scitula Syd. The following description is based on the Zambian material that has slightly smaller spores than those of the original published description (2). Uredinia were hypophyllous, brown, round, at first scattered irregularly in the interveinal areas, then coalescing to form a continuous erumpent covering on the base, margin, or middle of the leaflet. Urediniospores were yellow brown, verrucose, globose, triangular or oval, 20 to 25 × 20 μm, with densely filled oil globules, and the wall 2 to 2.5 μm thick. Paraphyses were peripheral, incurved, basally united, and 50 to 75 × 5 to 6.25 μm. The pathogen has been reported previously from Sierra Leone, Uganda, and Nigeria (1). To our knowledge, this is the first report of Olivea spp. in Zambia and the first report of O. scitula from Central Africa.

References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory, On-line publication. ARS, USDA, 2004. (2) A. H. Sydow. Ann. Mycol. 35:251, 1937.