Carter and Paraquat... Carter...
I posted two thread for you about Carter and paraquat.
TIME Magazone and a newspaper from Eugene, Oregon.
Wapedia - Wiki: Paraquat
.6. "Paraquat pot"
During the late 1970s, a controversial program sponsored by the US government sprayed paraquat on marijuana fields in Mexico.  Since much of this marijuana was subsequently smoked by Americans, the US government's "Paraquat Pot" program stirred much debate. Perhaps in an attempt to deter people from using marijuana, representatives of the program warned that spraying rendered the crop unsafe to smoke.