THE CHEMICAL CONTROL OF WATER WEEDS IN THE GEZIRA AREA OF THE SUDAN

Chlorophenoxyacetate weed-killers have been tested for the control of aquatic weeds in the canals of the Sudan Gezira. Using water in tanks, it was shown that 10 parts per million of sodium 2-methyl-4-chlorophenoxyacetate (Methoxone) or of sodium 2:4-dichlorophenoxyacetate (Fernoxone) would kill most of the angiospermous water-weeds found in the Gezira area.
Small-scale field experiments, using channels of known water capacity, have shown that not only leaves and stems but also seeds and underground rhizomes were killed in treated stagnant water, provided that the weed-killers were applied as dusts. The water remained toxic to crop plants for approximately 7 weeks after treatment.
In a large-scale experiment in 1950, treating normal irrigation canals, temporary weed clearance was attained, re-infestation was delayed, and one major canal, 4.5 km. long, remained weed-free 12 months after treatment.