The amount of land cultivated in Laos for opium has fallen 94 percent since 1998. The country now produces so little opium that it may now be a net importer of the drug, the United Nations says.

But there's probably no reason to call for import tariffs -- it looks as if Laos just doesn't possess a comparative advantage (relative to Afghanistan) in poppy production, for agricultural reasons:

This shift to Afghanistan has had major consequences for the global heroin market: a near doubling of opium production worldwide in less than two decades. Poppies grown in the fertile valleys of southern Afghanistan yield on average four times more opium than those grown in upland Southeast Asia.

So the shift to Afghan opium seems to comport with economic efficiency.

I am of mixed mind about the article, incidentally. It has some interesting reporting, but it never notes how worldwide opium prohibition -- the completely unnecessary worldwide opium prohibition, I might add (but would not expect the article to) -- converts the growing of poppies into a Big Issue, and renders opium use almost as problematic as the prohibitionists claim it is. The article is accompanied by a worthwhile photo of Chinese "inmates" at a drug rehab center: the pictured scene doesn't give me much faith in the medical underpinnings of the "treatment" that the inmates are receiving.

Source: http://vicesquad.blogspot.com/2007/09/laotian-trade-balance-suffers.html