Chemical control of water hyacinth and associated aquatic weeds at Itoikin near Lagos.
A survey of the diversion canal at Pump Station No. 1 of the Itoikin Rice Irrigation Project in Nigeria, conducted in Jan.-Feb. 1989, revealed that water hyacinth (Eichhornia crassipes), of which 2 forms differing in size and morphology were identified, covered about 88% of the entire canal, while Pistia stratiotes, Ipomoea aquatica, Ludwigia decurrens and Nymphaea lotus covered 9%, 1%, 1% and 1%, resp. Single spray applications of 3 kg/ha 2,4-D, 3 kg diquat ± a wetting agent, 4 kg ioxynil + 2,4-D, 3 kg paraquat and 2 kg terbutryn resulted in mortality of both forms of water hyacinth and associated aquatic weeds within 2 weeks of treatment (WAT). Between 2 and 8 WAT the dead weeds sank to various depths in the canal and, at the end of this period, the entire water surface was clear of all aquatic weeds.