ABSTRACT
About 150 species of aquatic and semiaquatic marginal plants create weed problems in one or more aquatic situations in the United States and Canada as well as other parts of the world. Extensive use of herbicides has been necessary for many years to replace or supplement mechanical methods of controlling aquatic and bank weeds and preserve agricultural, navigation, and recreational uses of the water resources. Aquatic herbicides, chiefly 2,4-dichlorophenoxy-acetic acid (2,4-D), have been used extensively for control of water hyacinth and certain other floating and emersed weeds in Florida and Louisiana since 1950. During the extensive, mostly unrestricted use of 2,4-D prior to 1967, no serious problems of injury to fish, livestock, or humans was apparent. During the years 1959 to 1962, about 100,000 acres of water hyacinth and alligator weed were sprayed with 2.4-D in the Corps of Engineers Aquatic Plant Control Program.
