Lyndel Meinhardt: There are a lot of threats out there that could severely impact the availability of that chocolate.

Lyndel Meinhardt is a plant pathologist with the U.S. Department of Agriculture. Cacao, the plant used to make chocolate, is highly susceptible to disease. Meinhardt said genetic diversity is one key to a heartier cacao crop.

Lyndel Meinhardt: We’re looking for trees that show no symptoms or signs of the disease or they have a large production even with the disease.

Meinhardt and his team have been looking for wild cacao near the Amazon River in South America. They’re collecting specimens of the ancestors of domesticated cacao – still growing in nature.

Lyndel Meinhardt: That material can then be utilized by those nations to try to improve the existing varieties of cacao.

Climate change models predict more extreme weather in this century. If it comes, Meinhardt said, unknown varieties of plants hold genetic keys to drought- or disease-resistant crops.

Lyndel Meinhardt: We have a set of DNA markers similar to what you might use in forensics medicine where they can actually identify individuals in the population – we have similar markers for the trees.

Cacao is a luxury crop, but corn, for example, is thought to have only a few crop wild relatives left. Scientists like Meinhardt believe it’s urgent to find and preserve the wild relatives of our food crops, to help secure global food supply.

Lyndel Meinhardt: This last trip, I believe we collected from 190 trees and 7 different river systems, which is one of the largest collections, expeditions that’s been done that I know of.

Lyndel Meinhardt says his research takes him to local villages.

Lyndel Meinhardt: And we’ll talk to the locals and we’ll ask them – do they know where any wild cacao is growing. And with that information we’ll go with a guide. And we’ll go out into the region and we’ll actually sample trees that he leads us to. Sometimes it’s very close to the River, sometimes it’s as far as half a mile away. We’re looking at the upper tributaries of the Amazon, toward the Andes in Peru.

Meinhardt talked about one fungal disease called Witch’s Broom.

Lyndel Meinhardt: It infects the tips of the trees and the tissues swell and it will start putting out shoots. The material just pops up from nowhere so it was called it a witches broom. Then the secondary cycles will actually create a pod rot.

Our thanks to Lyndel Meinhardt.
Lyndel Meinhardt is a plant pathologist with the Agricultural Research Service, a division of the U.S. Department of Agriculture. He’s an expert on cacao – the plant used to make chocolate – and he has extensively studied the major diseases that affect it. His research on cacao’s genetic diversity helps to identify new varieties that can be integrated into improvement programs, and to add new knowledge to the International Cacao Databases.

EarthSky also thanks agricultural geographer, Andy Jarvis of the Center for Tropical Agriculture (CIAT), in Cali, Colombia for his contribution to this post.