In the past three years, repeated spraying by crop dusters plus government programs to encourage farmers to pull up coca plants have reduced Colombia's coca, the source of cocaine, by 38 percent leaving 252,000 acres, according to a U.N. study.
What's more, coca cultivation appears to have stayed put in Colombia, for years the source of 90 percent of the cocaine on U.S. streets.
Fumigation is working, according to interviews and visits by the Los Angeles Times.
The U.S. State Department's goal is to halve Columbia coca production by 2005. So far it has cost $2 billion.
The success of the effort has left jobless thousands of dirt-poor farmers who seized on coca as a steady, if illegal, source of income, the Times reported.