"Chemical agents have been used since the 1970s (Mexico, Colombia). A variety of herbicides have been used, including paraquat in Mexico and Colombia, the chemical defoliant 2,4-D (a constituent of Agent Orange) in Burma and Bolivia, Tebuthurion (trade name Spike) in Peru and glyphosate (trade name Roundup) in Colombia. Typically, herbicides have been sprayed from aircraft so that larger areas of illicit cultivation could be destroyed. Planes used for aerial fumigation have come under fire, forcing them to fly higher than the optimum altitude (of between 5 and 20 feet) for application of herbicides and raising doubts about the accuracy and impact of the spraying. Concerns about human and environmental health have caused Peru, Bolivia, Ecuador and Thailand to ban the use of chemical agents for eradication."

Source

Mansfiled, David, "Assessing Supply-Side Policy and Practice: Eradication and Alternative Development," Global Commission on Drug Policies (Rio de Janeiro, Brazil: January 2011), p. 5.
http://www.globalcommissionon…