LA PAZ, Bolivia — On a hot December afternoon last year, 150 farmers in Chimore, a town in the Chapare region of central Bolivia, unloaded bananas and pineapples onto the Santa Cruz-Cochabamba highway. There was no market in sight and even if there was, the goods were not for sale. Rather, they were the building blocks of a road blockade.

The use of fruit as a barrier was purely symbolic. It is such produce that the Bolivian government has pushed, often forcibly, as alternative crops to coca, a leaf that for centuries has been used here for medicinal, cultural and religious purposes and from which these farmers have long made their living. It is, however, also the raw material of cocaine.

The outcome of this peaceful protest was two dead and dozens injured. As security forces set about dispersing the crowd, warning shots were fired. One of those killed was Casimiro Huanca, the leader of a local coca growers' federation of which the farmers are members.