Incorrect. The Taliban banned the cultivation of opium poppies in 2000, and enforced it, cutting the supply of heroin drastically (after the stockpiles of the stuff had been sold off as the price inevitably rocketed) That ban is now no longer in operation and opium is being grown again in large amounts.
http://www.mapinc.org/drugnews/v01/n904/a07.html
"They framed the ban "in very religious terms," citing Islamic prohibitions against drugs, and that made it hard to defy, he added. Those who defied the edict were threatened with prison. "