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World’s Chocolate Supply In Danger

December 18, 2008

Scientists say that as climate change increases, the world’s chocolate supply could start to run low.

Chocolate is made from the seeds of the cacao tree and in recent years demand has risen worldwide. But diseases destroy a third of the world’s cacao crop every year, and it’s getting worse.

Cacao is a rainforest tree with shallow roots that responds poorly to drought, and droughts have hit harvests hard in recent years.

However, the biggest chocolate company in the world, Mars Inc., has begun an unprecedented study of the cacao tree.

Africa grows 70 percent of the world’s cacao, mostly in the Ivory Coast and Ghana, where there has been only sporadic investment in improving the trees. The cultivated strains are prone to drought and diseases and few farmers can afford fertilizer. Pesticides are being used to boost yields and what efforts there have been to breed better trees have been discouraging.

“The yield of cacao has been flat for 30 years,” says Howard Shapiro, head of plant science at Mars.

Many peasant farmers who dominate cacao production are expanding the area of cacao through slashing and burning patches of rainforest, releasing nutrients on which the trees thrive for a time, after which the farmers move to a new patch. But this technique is contributing to deforestation.

Researchers agree that farmers need higher-yielding strains that produce big crops in response to fertilizer to make it worthwhile for farmers to buy fertilizer, allowing them to grow more cacaos on existing land.

Experts hope a switch to more intensive farming methods would not only reduce pressure on the rainforests but also help small farmers to prosper.

Monocultures of cacao are also very vulnerable to disease. Brazil’s cacao plantations were gutted in the 1980s when witch’s broom fungus was deliberately released amid local political disputes. Another even nastier fungus, frosty pod, destroyed plantations in Colombia and Costa Rica.

And there are fears that those threats could make their way to African crops.

“Those diseases will get out eventually,” says Dennis Garrity, head of the World Agroforestry Centre in Nairobi, Kenya. Without resistant trees, Africa’s biggest export crop could be devastated in as little as three years.

Juan-Carlos Motamayor of Mars’s cacao research program has analyzed more than 1200 cacao samples collected by other researchers over the years. They used a form of DNA fingerprinting to identify the samples and study the trees’ genetic relationships.

His team found that cacao samples could be divided into 10 genetically distinct groups, rather than three.

In June, Mars, along with the USDA and computing giant IBM, announced an unprecedented public-private partnership to sequence the cacao genome.

Meanwhile, the world’s small but dedicated bands of cacao scientists have begun searching for cacao trees with high yield, drought tolerance or disease resistance. Once these are identified, researchers will look for stretches of DNA that reveal which plants have these traits, which will greatly speed up breeding.

“If we can treble the yield of cacao, farmers can tear up two-thirds of their lowest-yielding trees and use the land to grow fruit and timber as well,” said Shapiro.

Garrity said besides giving cacao the shade it likes, growing other tree crops alongside it will give farmers harvests year-round and, hopefully, enough prosperity to abandon slash-and-burn for good. The use of nitrogen-fixing plants could reduce the need for fertilizer, while the mix of plants will reduce susceptibility to disease.

However, it isn’t just about saving the planet. “Breeders can also use DNA markers to create new chocolate flavors,” says Kuhn.

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