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.Full_Story