According to The Guardian today [A drug report offering hope as well as outdated claims about Britain | World news | guardian.co.uk], the greatest influence on the amount of poppy grown in Afghanistan is - the proce of wheat....
So against this background a substantial fall in global opium and cocaine production is to be welcomed as it demonstrates that a "war on drugs" rhetoric is not necessary to make progress. The UN report also reveals that it has been economics, more specifically rising wheat prices rather than military action, that has triggered the fall in opium production in Helmand province in Afghanistan: "The decline in cultivation occurred despite a sharp decline in opium poppy eradication from 19,047 hectares in 2007 to 5,480 in 2008."
Interesting...