Apparently our government and the US government are funding research into biological warfare agents that specifically destroy drug crops. They are breeding fungi that kill particular target species. In June the Sunday Times and the BBC revealed that the British government funded reasearch into diseases of opium poppies in Uzbekistan. More recently the US has admitted - "admitted" isn't the word, they are proud of this - research into fungi to attack hemp and coca.
Of course these fungi would only be used against poor farmers in poor countries. It's not meant for us. Most of this stuff is grow here anyway - you can see opium poppies in back gardens all over England, opiates including heroin are vital and frequently prescribed medicines, and hemp (grown for fibre) is a massive legal crop in France and still of some significance in England (a thousand years ago it was one of our main crops).
Ignore the obvious application of this research in more "traditional" warfare - a technique that can be used to destroy poppies or coca or hemp might also be used to destroy rice or yams or mangoes or sorghum. That for the first time gives a weapon which can be used against a particular nation or ethnic group within a nation. Who other than Ethiopians would be seriously affected by a plague that wiped out tef? A plague that destroyed bananas would be unpleasant for everybody, and economically disastrous for many in the Caribbean and Central America, but it would kill Baganda. And don't forget that the big agribusiness companies are pushing their patented hybrids and genetically manipulated crops into the hands of poor farmers all over the world, encouraging monoculture. And these are the same people who are helping the CIA poison fields in Colombia. They are shoving monocultures of plants they know how to kill onto all the farms of the world. Who needs sanctions when a single spray plane could wipe out all the wheat in Iraq or Serbia?
Ignore also the huge dangers of such fungi cross-infecting other plants, including maybe crops. These things are sexually reproducing, have close relatives in the wild, disperse by spores. The danger involved is far, far greater than the danger from foodcrops genetically manipulated to be resistant to certain herbicides (although they are bad enough - mainly because they reinforce the hegemony of a few huge private corporations over the lives of millions of poor farmers).
Even ignoring all those dangers which would guarantee that eny well-informed government that was either sane or moral wouldn't touch this with a barge-pole - even ignoring all that it is sickening to think of rich Europeans and North Americans destroying the livelihood of poor farmers in other countries who are only growing this stuff because we buy it.
It's not a biological problem it's a political problem and it's called neocolonialism.