"Critics note that the spraying has not prevented the tripling of the area under coca cultivation since Pastrana's inauguration, and that the spraying simply destroys the means of livelihood of subsistence farmers and displaces the crops deeper into the jungle. The coca producers have also adapted by developing new varieties of the coca plant, such as the Tingo Maria, which produces three times as much coca as the traditional varieties."

Source

Rabasa, Angel & Peter Chalk, "Colombian Labyrinth: The Synergy of Drugs and Insurgency and Its Implications for Regional Instability" (Santa Monica, CA: RAND Corporation, 2001), Chapter 6, p. 66.