STUDIES IN THE BACTERIAL DISEASES OF SUDAN CROPS: II. BACTERIAL LEAF BLIGHT DISEASE OF CASTOR (RICINUS COMMUNIS L.)

The bacterial disease of castor in the Sudan has been reinvestigated. Typically the disease symptoms are brown or black, round or angular lesions on leaves; occasionally the thin succulent branches are attacked, but not the vascular tissue.
The bacterium responsible for the disease was previously thought to be Pseudomonas solanacearum E.F.Sm. but comparative studies show that the Sudan species differs in pathogenicity and physiology from P. solanacearum. It closely resembles Xanthomonas ricinicola (Elliott) Dowson (= Bacterium ricini Yoshi and Takimoto) in characters, host range and pathogenic effects. In culture on solid media the growth of X. ricinicola is typically yellow, while that of the Sudan species is dirty white; but this difference is not considered sufficient to justify the establishment of a new species.
The author proposes the specific name ricini originally adopted by Archibald (1927) and Yoshi & Takimoto (1928), for the species of Xanthomonas causing the leaf blight disease of castor, and considers that the causal organism in the Sudan is an atypical strain of this species.     

THE WHITE-BREASTED CORMORANT IN SOUTH AFRICA

Akinsola, O.A., Ezealor, A.U. &; Polet, G. 2000. Conservation of waterbirds in the Hadejia-Nguru Wetlands, Nigeria: current efforts and problems. Ostrich 71 (1 &; 2): 118–121.

The ornithological importance of the Hadejia-Nguru wetlands at both national and international levels is well known. Current efforts at conserving the avifauna of the wetlands started with the establishment of the Hadejia-Nguru Wetlands Conservation Project (HNWCP) in 1987, as a joint international initiative to promote sustainable use of this hydric ecosystem in the otherwise semi-arid zone of north-eastern Nigeria. The present phase of the project started in 1995 with the major goal of maintaining the natural resources and function of the wetlands. This paper discusses recent activities of the project that have been directed towards conserving the wetlands, particularly its avifauna.

Bird monitoring and the annual dry season (northern winter) waterbird surveys remain the most publicised bird conservation effort of the HNWCP. However, recognition of the vital and central role of water in maintaining the ecological health of the wetlands has prompted the project to evolve a new strategy of regular meetings of the wetlands' water stakeholders (tagged “water-use advocacy”), to resolve periodic water-shortage and distribution problems.

Uncontrolled hunting of birds and habitat loss remain pressing problems throughout the wetland. The HNWCP has made efforts to curb these problems by sensitising the local communities through awareness campaigns and harnessing the efforts of concerned local and national organisations. However, the HNWCP has had difficult experiences regarding the problems of crop damage by avian pests from the wetlands.     

EICHHORNIA CRASSIPES IN SOUTH AFRICA - A GENERAL REVIEW

SUMMARY

The food from the gut contents of 853 Barbus mattozi of various sizes were examined and analysed. The results showed a dietary transition from planktonivorous and omnivorous to piscivorous with increasing size of fish. At sizes larger than 230 nm fork length the diet became 100% piscivorous.