Bananas, cocoa mix with tires in new farming approach

Latex, the base ingredient in rubber, is harvested from hevea trees much like maple syrup. It drops into buckets, which will be emptied when full. Latex, the base ingredient in rubber, is harvested from hevea trees much like maple syrup. It drops into buckets, which will be emptied when full. (CNS Photo courtesy of Rich Dole/Michelin)

In a scene from the 1932 melodrama "Red Dust," Clark Gable and Mary Astor watch plantation laborers pour a white liquid.

"It's milk!" Astor exclaims.

"Oh no, just rubber," says Gable. "But you could drink it.

"If you care to stretch a point!"

Bad puns aside, it wasn't technically rubber, either. It was still latex at that point; pure latex is what flows from tapped trunks of the hevea brasiliensis, or rubber tree, much like maple syrup.

Latex is the essential base ingredient in the rubber needed to make everything from tennis shoes to balloons to auto tires. Latex becomes rubber after it is subjected to high heat and mixed with a curing agent, such as sulfur, which makes it hard, durable and non-sticky. This process, discovered in 1839 by Charles Goodyear, is called vulcanization - after Vulcan, the Roman god of fire.

The first automobile tires were white, just like the raw latex. But, later, carbon black was added to improve traction characteristics. Voila! Black tires.

The process hasn't changed much since "Red Dust" days, although tires have more ingredients, such as chemicals and polymers, in them today. In fact, the amount of actual latex in the average passenger car tire is now about 40 percent; the percentage is higher - about 65 percent - in truck tires because they need stronger sidewalls and better weight-carrying ability. And that is an area where latex still provides irreplaceable strength.

The hevea tree is native to Brazil, and for many years they would only grow in their natural habitat. About a century ago, however, the trees were finally successfully transplanted to Africa, Siam, and Malaysia. Now, more than two-thirds of the world's rubber production comes from the Southeast Asia area, where the plantation system has been mostly replaced by small farms run by families, who sell their latex production in a cooperative market system operated out of Singapore.

While rubber production is thriving in Asia, the industry is struggling in the place where it originated, in Brazil. Most of the trees were originally most prevalent in the Amazon River basin. But most trees, in the past 50 years or so, have developed a parasite or fungus that caused latex production to be drastically reduced.

So the plantation operators moved to eastern Brazil, in the Atlantic rain forest area of Bahia state, where production was still booming. Unfortunately, when they brought their tools with them, the tools brought the fungus, and soon the Bahia trees were infected, too. So far, the parasite has proven too tough to tame.

But now Michelin, which several decades ago bought Firestone's once-widespread operations in Brazil, is thinking of better ways to run a plantation - by not running one at all. Michelin has subdivided its plantations into parcels of about 1,000 acres each and subcontracted ownership of those blocks to husband-and-wife teams. The couples, in turn, take over growing hevea trees, tapping them for latex and harvesting it. Michelin promises to buy their harvest at fair market rates.

But that is not the end of Michelin's involvement: The company has devised a program to help improve yields from the acreage, by devising a plan by which the owners can grow cocoa and banana plants in alternating rows between the hevea trees.

Hevea must be planted at least a few yards apart, so they don't compete with each other for sunlight. That leaves a little room for something else to be grown in the empty spaces.

The hevea trees, which grow at least 30 feet high, provide a welcome amount of shade for the cocoa - essential to chocolate production. The family farmers, understandably, have a lot of motivation to produce three cash crops, instead of just one.

Michelin is also continuing its research and testing into what is infecting the hevea trees. Healthier, more disease-resistant trees are being developed by Michelin scientists. The healthier varieties are then provided to the family farmers, who cut down the worst of the diseased trees (even diseased trees keep yielding latex, albeit at reduced rates) and replace them with new, healthy trees.

Michelin has also retained a large swath of land bordering the old Bahia plantation, and has turned it into a nature preserve. This area includes a diverse, natural ecosystem that attracts scientists from around the world, who study its flora and fauna. The preserve also protects some scenic wonders, like the huge Pancada waterfall, which can be viewed by the public.

Michelin says it is committed to continuing to help find better, more socially conscious ways to harvest latex and produce rubber. It is new green technology, but the tires will remain black.

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