|The US State Department estimated that Mexico grew 12,000 hectares of marijuana in 2009 [John Holman/Al Jazeera]
The small aircraft touches down in a tiny dirt track airstrip, hidden in the folds of the surrounding mountains. A crowd of men wait for us in pickup trucks. They are heavy set, clad in jeans and trucker hats. Strong hands grasp ours in greeting before we all clamber onto the pickups, and the strange convoy sets off. Our destination is a three hour ride away over a dirt road, weaving around the edges of giant canyons and plunging through clear mountain streams.
We are in the Sierra Madre, the 'Mother Mountains' of Northern Mexico. In a country currently struggling against a wave of drug led violence, these rugged lands have long been the apex of all that is wild, violent and illegal.
Here, blood feuds regularly erupt that can wipe out entire families. It's not an uncommon sight to see farmers work with rifles swung on to their shoulders. Many of them are employed in producing the only crops that really pay here: marijuana and heroin poppies.
The cash cow of the Sierra Madre
Strangers are not welcome here. We arrive with Martin Solis, a man born in these mountains and who has twice been mayor in neighbouring town Guachochi. Now, he works for the Chihuahua state government. Slim, ruddy and sporting a Stetson hat, he greets a dark eyed, softly spoken man as we ease our way off the plane.
This man is Lico. He is the leader of the community, both in their legal and illegal activities, Solis tells us. Lico speaks softly, but carries an air of command. The land we are travelling in is all his, and the men perched in, and on, the other pickup trucks are all his relations.
After rumbling past boulders and up steep pothole ridden slopes for most of the morning, we finally arrive at an expanse of emerald green. The convoy lurches to a stop and we climb gingerly down, to be assaulted by the powerful aroma of thousands of marijuana plants.
In 2009, the US State Department estimated that around 12,000 hectares of marijuana were grown in Mexico, a 35 per cent increase on the year before. Much of it was cultivated here in the Sierra Madre. Farmers have been harvesting "the crops that pay" for four decades, seemingly impervious to repeated Mexican army campaigns to slash and burn the small parcels of marijuana that cover the mountains.
As we clamber amongst the chest high cannabis plants, Solis, the State government representative, watches on impassively from the sidelines. It's difficult for the government to deny the existence of the main cash crop in this region, and it's proved just as difficult to eradicate it.
However, recently the Chihuahua State Government has had a different idea to wean farmers away from their biggest cash crop.
A series of factors have been driving marijuana prices down in the Sierra Madre, Solis says. The upsurge in marijuana production in California has reduced demand here. Drug gangs fighting over supply routes from the Sierra Madre have exacerbated problems. Whilst the battle continues, the farmers say it's difficult to move crops, and this year's harvest remains in the warehouse.
With the downturn in fortunes for marijuana growers, the state government spotted an opportunity. In January of this year, Solis was placed in charge of a programme to offer farmers the resources and support to grow alternative crops.
Avocados were chosen for the scheme. They grow well in the Sierra Madre soil and are currently fetching a high price, due in itself to a shortage from avocado farmers in the southern state of Michoacan, who are encountering problems with drug gangs.
Since the start of the programme, Solis has helped farmers plant 80,000 avocado trees in 200 hectares across the Sierra Madre. The state government provides the plants, along with fences and irrigation technology.
It has appeared to meet with early success; farmers in eight of the Sierra Madre's 17 municipalities have joined in, but Solis is pragmatic about their reasons.
"We arrived just at the moment when growing drugs stopped being good business and people wanted something that gave them a better income. That's why farmers are entering the scheme, not because of any social conscience, but because they want more money."
Debating the future
We finally arrive to what he wants to show us, fields with sprouts of avocado crops growing a few hundred metres down from the marijuana plantations.
The avocado trees are flourishing in Don Manuel Loera's plot of land. He shows us around, inspecting the plants with his large, work-stained hands. Speaking deeply from beneath an impressive moustache, he says that he had grown marijuana all his life but was tired of always looking over his shoulder.
"I wanted to grow something legal, to not be always looking out for the law."
However, experts in drug policy remain sceptical as to whether the programme could eventually replace drug growth in the mountains. Edgardo Buscaglia, an international security expert, says there is little the government can do to affect trade.
"Even when considering that marijuana is just a minuscule proportion of total annual gross income for the Sinaloa organisation and other Mexican organised crime groups, one can say with confidence that international market forces have much more power to determine the relative attraction to farmers of marijuana growing than anything that the Mexican government could do locally regarding eradication or substitution programmes."
However Alejandro Madrazo Lajous, a Mexican lawyer working on drug law reform, says that at least the programme marks a new direction for official policy.
"It is good that states take their own initiatives and break rank from simply following the federal government's failed policy of repression as the first and last measure, to which President Calderon has stubbornly stuck to. A lot of state violence is directed towards producers of the crops, who are often the poorest in the supply chain, and it's great if this means a change of approach. This programme is not going to solve the problem, but it shows a shifting of attitudes, which should be encouraged."
The hopes of Martin Solis are more modest. He says the programme is designed to give farmers who depend solely on drug crops another option. Whether they take it is up to them.
As we head back to the tiny air strip, Lico and the rest of the convoy break out bottles of lechugilla, the bootlegged liquor famous in this region. Hurtling round the mountain curves, our increasingly boisterous escort becomes more enthusiastic about the avocado programme than ever.
Still, it will not be an overnight solution. It takes two years for the first crops to ripen, but even then, farmers such as 24 year-old Edmundo Loera, who currently grows marijuana, remain optimistic that a change could be afoot.
"My children won't have to do what I do here if the avocado scheme takes off."
Whether that enthusiasm is enough to break the habits of a lifetime for those in this hard and remote corner of Mexico is the real test of the programme.
Follow John Holman on Twitter: @mexicorrespond