NECHI, COLOMBIA — Cesar Lopez and his crew resemble human weed eaters, dispensing with 15 acres of illegal crops a day in the sweltering hills of north-central Colombia.
Guarded by a cordon of 120 anti-narcotics police officers, the group uses metal rods to uproot bush after bush on the steep hillside. In a gully below stands a thatched-roof laboratory where farmers processed a kilogram of coca paste a week, worth about $1,000 each, before fleeing last month, police said.
Lopez leads Mobile Eradication Group 5, one of scores of 30-man teams of laborers the government has deployed across the nation to manually destroy coca crops, a program now deemed nearly as important to the drug fight as sprayed weedkiller.
On a recent day, Lopez and his comrades were on the outskirts of this river town in Antioquia state. They marched into the hills that are polka-dotted with distinctive lime green patches of the shrub whose leaves are cocaine's raw material.
"We just keep going until it's gone," said Lopez, 32, a wiry onetime narco-trafficker who gave up coca farming after tragedy struck. "I feel proud of what we do because I know from experience these bushes are the root of all that's evil in Colombia."
Spraying from crop-dusters is still the preferred eradication weapon of Plan Colombia, the U.S.-funded initiative targeting illegal drugs and terrorism. But disappointing results from years of aerial spraying, plus fears of environmental damage caused by the chemicals used, have led U.S. and Colombian officials to put more emphasis on teams like Lopez's.
This year, ground crews will destroy 250,000 acres of coca, 67% more than in 2007, compared with the 325,000 acres of coca to be sprayed this year, Colombian and U.S. officials said. Five years ago, manual eradication represented less than one-tenth of all coca crops destroyed, the officials said.
The shift is having an effect, the White House Office of National Drug Control Policy says. In a visit to Colombia last month, the office's director, John P. Walters, said street prices of cocaine in the States were up 6% in the 12-month period that ended June 30 and up 25% since January 2007.
Higher prices indicate that efforts to control the supply and trafficking of cocaine are working, Walters said.
"There has been a market meltdown in the cocaine business," Walters said in an e-mail to The Times. "We have made huge strides in breaking the machine that delivers addiction, violence and misery to our nations."
But Plan Colombia critics are skeptical, saying that cocaine street prices fluctuate and the White House discloses little about how its data are developed or what measurement methods it uses. Previous claims of higher prices have been challenged by news organizations that have surveyed the same urban markets the Bush administration cites.
"This White House just doesn't have the credibility to ask people to take their word for it," said John Walsh, a researcher at the Washington Office on Latin America, a watchdog organization. "If they can't back it up with data that's open to independent expert scrutiny, they're going to have a tough time convincing people."
Some say any shrinkage of the U.S. supply is explained by the growing market in Europe, where much of South America's drug production has been redirected because it can fetch higher prices there.
The police officers watching over Lopez's group acknowledge being nervous -- it's a dangerous job. Snipers with the Revolutionary Armed Forces of Colombia, the country's main rebel group and largest cocaine trafficker, frequently take aim at them from dense jungle perches that adjoin coca clearings.
At night, stealthy killers called zorros sneak up on police sentries at worker camps to attack them with knives or guns.
But the biggest danger comes from land mines that guerrillas plant in coca fields to dissuade the workers from doing their job. Often assembled with gravel, wood splinters and fecal matter encased in rubber, the mines are sometimes difficult to find, even with metal detectors and explosives-sniffing dogs.
"The terrorists have become very inventive," police Col. Harold Santamaria said.
An average of two land mines a week are detected by police. One that wasn't noticed exploded Oct. 17, blowing off the leg of a lieutenant guarding Lopez's unit. This year, in this region alone, one police guard and one eradicator have been killed and seven wounded by mines and snipers.
Since the manual eradication program began in earnest in 2003, the toll has been heavy, with dozens of soldiers, police officers and eradicators killed, including 24 in two months in 2006, when guerrillas attacked teams in Macarena National Park, a rebel stronghold.
"Psychologically, it's a heavy load," police Maj. Delfin Murillo said. "But our people never lose their spirit. They see they are having an impact."