SCENES FROM A FAILING STATE: They’re not avocados, they’re ‘green gold,’ and hyperviolent drug cartels have sights set on them.

Small-scale avocado growers armed with AR-15 rifles take turns manning a vigilante checkpoint to guard against thieves and drug cartel extortionists in this town in the Michoacan state, the heartland of world production of the fruit locals call “green gold.”

The region’s avocado boom, fueled by soaring U.S. consumption, has raised parts of western Mexico out of poverty in just 10 years. But the scent of money has drawn gangs and hyperviolent cartels that have hung bodies from bridges and cowed police forces, and the rising violence is threatening the newfound prosperity. A recent U.S. warning that it could withdraw orchard inspectors sent a shiver through the $2.4 billion-a-year export industry.

Some growers are taking up arms. At the checkpoint in San Juan Parangaricutiro, the vigilantes are calm but attentive. They say their crop is worth fighting for.

I wish all the luck in the world to these farmers, but the cartels have the big battalions.