US pot growers pose threat to Mexican cartels

Stiff competition from thousands of small-scale marijuana farmers in the US threatens the bottom line for powerful Mexican drug organisations in a way that decades of arrests and seizures have not, police and pot growers say.

Illicit pot production in the US has been increasing steadily for decades. But recent changes in state laws that allow the use and cultivation of marijuana for medical purposes are giving US growers a competitive advantage, challenging the traditional dominance of the Mexican traffickers.