In June I spent 15 hours on a mule visiting peasant communities in northern Colombia where coca plants are grown for the cocaine industry.
Many of the peasants complained to me that their legitimate crops of corn, plantains and cassava were being wiped out by a controversial aerial fumigation program.
The U.S.-financed spraying was meant to hit the drug crops. But it was clear to me after three days that it wasn't very accurate. In some places the coca plants were bushy and green, while other legal crops nearby were dead, their leaves turned ashen gray.
The good news is that the Colombian spray program appears to be nearing an end. After years of political, social and diplomatic wrangling, Colombia quietly announced last month that it is scrapping the use of spray planes in favor of manual eradication.
Recognizing that the spray program had been largely counterproductive, Colombia's President Alvaro Uribe said in a speech that "instead of uniting Colombians around the idea of eradicating drugs," it "causes complaints and provokes reactions against eradication."
In the future, he said, spraying would be used as only a "marginal" part of the counterdrug strategy.
For years policymakers in the United States and Colombia argued that spraying needed time to bear fruit. The idea was that persistent spraying would eventually deter farmers from continuing to grow.
Well, they had two decades to prove that and couldn't.
Spraying has had little impact on reducing drug cultivation in Colombia. The area I visited in northeastern Antioquia state historically never had coca until heavy spraying of big plantations in the south of Colombia forced the industry to scatter like mercury across the country.
There has been no significant drop in the amount of coca under cultivation - a 10 percent decline from 417,000 acres in 2001 to 380,000 acres in 2006, according to official U.S. figures.
But it would be wrong to think that Colombia came to this realization on its own. Rather, Uribe was responding to signals from Congress, which funds the spray planes, the gallons of glyphosate herbicide (extra-strength Roundup) they carry and all the sophisticated equipment used to guide pilots to their targets.
In the current budget debate for U.S. aid to Colombia, both the House and the Senate have made it clear they have lost faith in the spray effort.
Lawmakers are proposing deep cuts in military assistance to Colombia, as much as $160-million, with most of it coming from the spray program.
"The Colombians were reading the tea leaves," said John Walsh, a longtime critic of U.S. counter-drug strategy at the Washington Office on Latin America. "It's so expensive and so controversial, and it's given them a lot of headaches," he added, citing a recent diplomatic dispute with Ecuador over spraying along the border between the two countries.
"The (Colombian) government was never so convinced about fumigation," said Alfredo Rangel, director of the Security and Democracy Foundation in Colombia. "What sustained it was U.S. insistence and funding."
Colombian officials describe their change of heart as an "evolution" of counterdrug strategy. "Manual eradication can be more effective and, at times, cheaper," Colombia's Defense Minister Juan Manuel Santos told reporters in Washington during a recent trip to discuss future counterdrug aid.
But, as American counterdrug agents are finding in Afghanistan, manual eradication isn't much of a solution either, analysts point out. It requires security on the ground in order to be implemented, something still lacking in Colombia.
Journalist Jon Lee Anderson recently provided a vivid account in the New Yorker magazine of American counterdrug officials forced to flee under attack from suspected Taliban gunmen during an opium poppy eradication operation.
"Attacking the plant isn't the answer," Rangel said. "You have to stop the (drug processing) chemicals getting in and the coca paste getting out. It's all about interdiction."
Only by doing that, Rangel argues, does the plant itself lose its market value, forcing the peasant farmers to turn to legal, alternative crops.
Therein, of course, lies another dilemma. As I found out on my recent mule trek, in Colombia's remote countryside there are no roads and electricity for farmers to get crops to market profitably.
"Manual eradication will only work if it's done in concert with finding alternatives for the farmers," Walsh said. "That's only been an afterthought until now. Hopefully that's finally being recognized."
David Adams can be reached at email@example.com.