Slow Death to Chocolate?

Yes! Yes! Yes!

IT'S chocolate egg season again, and sales of the pagan and Christian symbols of rebirth are as strong as ever. But the hunt for Easter eggs may truly be on next year, because chocolate trees are in increasing trouble.

Chocolate is made from the fermented, roasted seeds of the cacao tree. The cacao swollen shoot virus (CSSV) can kill the trees, and threatens to slash this year's spring crop by a third in the world's biggest producer, Ivory Coast. Meanwhile a fungus called witches' broom is doing the same in Brazil. Now researchers are racing to sequence the cacao genome and find genes that can resist CSSV.

Cacao trees are native to the Amazon rainforest, but west Africa produces 70 per cent of the world's cocoa, virtually all on tiny, impoverished farms. In recent years, demand for chocolate has mushroomed. The farmers cannot afford expensive fertiliser so they boost production by planting more cacao trees over a greater area. That means cutting down other trees that normally grow between cacao crops, which also replicate their rainforest origins and give them the protective shade they prefer.

"Increasingly cacao is grown almost as a monoculture," says Paul Hadley of the University of Reading, UK. That promotes the spread of disease, as does the trend towards growing the trees in drier regions - water-stressed cacao trees are less able to fight off disease.