Tackling Tough Problems in the World of Chocolate

By Alfredo Flores
February 10, 2004

Here's some sobering news for Valentine's Day gift-seekers: All is not well in the world of chocolate. That's because several fungi, most significantly Crinipellis perniciosa, are attacking Theobroma cacao trees, source of the seeds that are the chief ingredient for cocoa and chocolate. C. perniciosa penetrates the stem and fruit tissue of cacao trees, inhibiting their formation of seed pods and destroying mature pods.

But scientists with the Agricultural Research Service have been tackling the problem. Raymond J. Schnell and colleagues at ARS' Subtropical Horticultural Research Unit in Miami, Fla., have studied cacao's genome and have found genetic markers for resistance to witches' broom, the disease caused by C. perniciosa.

Schnell and other ARS scientists are participating this week in a first-of-its-kind symposium on T. cacao, hosted by the National Academy of Sciences in Washington, D.C. Schnell will discuss research on cacao's genome, its historic origins, and current and future challenges in tropical tree crop breeding. The meeting is expected to draw scientists from Germany, France, Switzerland and Austria, as well as the United States, to discuss recent advances in cacao research.

Latin America was a traditional hub of cocoa production until witches' broom began to devastate production a little more than a decade ago. Since then, Brazil, which used to export $100 million worth of cocoa beans to the United States annually, has gone from being the world's third-largest exporter to a net importer. Western Africa is now the world's premier cacao-growing region, with the Ivory Coast supplying about half of the world's cocoa beans.

Schnell is currently in the third year of a five-year cooperative agreement with Masterfoods, Inc., of Hackettstown, N.J.--makers of M&Ms, Dove Chocolate and Snickers candy bars--to breed cacao that resists serious diseases. Breeding populations established in Costa Rica and Ecuador have shown tolerance to witches' broom and to frosty pod and black pod, both of which rot cacao pods, as well as to Ceratocystis, a fungus that causes cankers on branches and stems.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.