Aquatic Weed Management: Integrated Control Techniques for the Gezira Irrigation Scheme -- Report of a Workshop 3-6 December 1978
This paper summarizes a workshop on the management of aquatic weeds in the irrigation canals of the Gezira Scheme, Wad Mehani, Sudan. The workshop, held December 3-6, 1978, was sponsored by the U.S. National Academy of Sciences -- National Research Council (NAS/NRC) and the University of Gezira. The broad objective of the workshop was to formulate recommendations for an integrated weed management program using short- and long-term control techniques. Minor irrigation canals, which channel water off of the main canals to irrigated fields, are easily invaded by aquatic weeds that impede water flow and promote malaria and bilharzia vector growth. Aquatic weeds can be floating, immersed, or submersed. Submersed weeds cause the most serious problems, and are the most difficult to control. Aquatic weeds are presently controlled using either biological, herbicidal, mechanical, or manual methods. Draw-down control methods are no longer used because of the advent of intensive, year-round cropping. Mechanical control is an expensive technique. Herbicidal control requires special equipment, trained personnel, and further knowledge of weed species' life cycles, physiology, and reproductive characteristics. Biological control methods remain largely untested. Whichever method is chosen must be compatible with the multiple uses of canal waters, which include drinking, cooking, and bathing. The workshop agenda, working group reports, recommendations, observations, and conclusions are included. Papers presented at the workshop, which cover topics of aquatic weed management, malaria and schistomiasis control in irrigated canals, gravity-flow irrigation, and use of the Chinese grass carp as a biological control agent, are reproduced in the second part of the report. A list of references is included.