Corre Coyote, Mexico ? Times are good for the dope growers of the western Sierra Madre mountains. The army eradication squads that once hacked at the illicit marijuana fields have been diverted by the drug war that’s raging elsewhere in Mexico.

The military’s retreat has delighted farmers who are sowing and reaping marijuana. Cannabis cultivation in Mexico soared 35 percent last year and is now higher than at any time in nearly two decades, the State Department says.

It’s also been a boon for Mexico’s powerful organized-crime groups.

Marijuana is perishable, bulky and less profitable than their other exports — heroin, cocaine and crystal meth — but drug trafficking experts say that every major trafficking organization in Mexico reaps significant income from marijuana, drawing on cross-border criminal networks that carry cannabis to scores of U.S. cities.

“They tend to be a cash cow for the drug trafficking organizations,” David T. Johnson, the assistant secretary of state for international narcotics and law enforcement affairs, said during a visit to Mexico last week.

An aerial tour deep into the Sierra Madres at the side of a Mexican army general and a small army eradication unit — one of a handful that are still actively working — shows marijuana crops flourishing in valley after valley of the rugged, pine-covered region.

The mountain slopes and valleys in the part of southern Chihuahua state that’s hugged by Sinaloa and Durango states are sometimes called Mexico’s Golden Triangle — after the opium-producing Golden Triangle of Southeast Asia — because of their productivity. Illicit crops include not only marijuana but also poppy, the flowering plant that provides the white gummy latex that’s later processed into opium and heroin.

It’s a dangerous area. Even the poorest farmers tote weapons. A third of the region’s population is thought to earn its living from the illicit drug industry.

Peasant farms need little to grow small fields of marijuana: bags of seeds, some fertilizer, lengths of hose for primitive irrigation systems and a few months for the crop to mature into 10-foot-tall plants.

According to State Department estimates, the areas of harvestable marijuana fields in Mexico grew from 10,130 acres in 2001 to 29,652 acres in 2009. During the same period, the area of eradication dropped by half.

Destroying marijuana crops isn’t easy. Unlike Colombia in South America — which aggressively uses armored aircraft to spray herbicide on coca fields, killing the raw ingredient for cocaine — Mexico largely relies on the brute force of troops to yank up marijuana crops.

On a recent day, sweat poured off soldiers as they tugged to uproot tall marijuana plants. The marijuana grew in a carefully tended field adjacent to a creek. Even without much fertilizer and in rocky ground, the weed grew robustly. When the soldiers couldn’t pull up the plants, they hacked at them with machetes.

Then, with a good dousing of gasoline, the piles of uprooted plants went up in flames.

After a dozen soldiers had worked hard for several hours, barely an acre or so of weed had been pulled up and burnt.

Farmers see little stigma — or risk — in growing cannabis.

“It’s always been said that poppy is controlled by organized crime, and marijuana is for the people. Growing it is like growing corn,” said the general, who spoke to a journalist on the condition — set by Mexico’s Defense Ministry — that he not be named.