LA RUANA, Mexico - The farm state of Michoacan is burning. A drug cartel that takes its name from an ancient monastic order has set fire to lumberyards, packing plants and passenger buses in a medievallike reign of terror.

The Knights Templar cartel is extorting protection payments from cattlemen, lime growers and businesses such as butchers, prompting some communities to fight back, taking up arms in vigilante patrols.

Lime picker Alejandro Ayala, 41, chose to seek help from the law instead. After the cartel forced him out of work by shutting down fruit warehouses, he and several dozen co-workers, escorted by Federal Police, met on April 10 with then-state Interior Secretary Jesus Reyna, now the acting governor of the state in western Mexico.

On the way back, his convoy was ambushed, twice. Ayala and nine others were killed.

Help finally arrived Sunday when thousands of soldiers rolled in to restore order. The government of President Enrique Peña Nieto says troops will stay in Michoacan until every citizen lives in peace. But the offensive, headed by Secretary of Defense Salvador Cienfuegos, looks a lot like failed operations launched previously by former President Felipe Calderón.

Calderón was trying to stop drug cartels from morphing into mafias controlling all segments of society. But that's exactly what has happened.

In the Tierra Caliente, a remote agricultural region, fire has been a favored weapon of the cartel. On the highway between Coalcoman and La Ruana, the ruins of three sawmills torched by the cartel still smoldered this week.

The owners reportedly had failed to pay protection fees of 120 pesos (about $10) for every cubic meter of wood they sold, the equivalent of about 10 cents for every 2-by-4 board.

The heart of a conflict where a mafia openly rules and the government is largely absent is nowhere more evident than in the lime groves.

Mexico is the world's largest producer of limes, according to the U.S. Department of Agriculture. Much of its exports go to the United States, and Michoacan contributes a large share of that.

By late last year, the cartel wasn't just extorting money from lime growers and packers. It had started charging per-box payments from lime pickers, who can ill afford it.

With officials doing nothing, self-defense groups started to spring up in February. Heavily armed men began patrolling the countryside, sometimes openly battling the cartel.

Then the cartel shut the warehouses, forbidding brokers to buy limes and cutting off work for the pickers who had revolted.

Meanwhile, in Mexico City, the federal government recently declared a lime emergency because prices had doubled to about 70 cents a pound For a fruit so central to Mexican cuisine, it was a crisis.

The government announced last week it would tackle the shortage by importing limes from Brazil. The government attributed the local scarcity to crop pests and fluctuations in production.

"Isn't it ironic, Mexico is going to import limes from Brazil, because there isn't enough supply?" asked a rancher at the headquarters of the local self-defense group in Tepalcatepec. "Here, the limes are falling to the ground, because the lords of the Knights Templar won't let them be sold."