Signs of Winter 6: Chocolate

Photo by 4028mdk09. Wikimedia Commons

(Please click here to listen to an audio version of this blog!)

Winter is a great time to talk about chocolate. There is nothing like a cup of cocoa or a heavily-chocolated mocha coffee to help ease away the cold of these dark days. Also munching chocolate bars while hiking in the snowy woods (or even when you are just looking out the window at the snow!) helps you to feel at peace with the season.

Chocolate is the well processed product of the seeds of the cacao tree. Cacao trees are native to Mexico and Central and South America, and the use of chocolate can be dated back to 1500 BC and the Olmec civilization of present day Mexico. Recent genetic studies suggest that the cacao originated in the Amazon basin but spread quickly along the active trade routes between the early Mesoamerican societies.

Cacao tree. Photo by International Institute of Tropical Agriculture, Flickr

The cacao tree (Theobroma cacao) is a small (15 to 28 foot tall), evergreen, understory tree of wet tropical forests. They have very narrow temperature tolerances (optimally 70 to 90 degrees F with 59 degrees F as the lethal low-tolerance point), and require a great deal of moisture (optimally around 80 inches of rainfall a year). Cacao, therefore, can only be grown in the tropics (the 20 degree N and S latitude band around the equator).  Different strains of cacao make different kinds of seed pods, but all of their seeds can all be processed into chocolate.

Chocolate is incredibly popular around the world. An estimated one billion people consume chocolate on any given day! The average American eats between 10 and 12 pounds of chocolate a year (different sources have slightly different estimates!). For comparison, though, the average person in Switzerland eats almost 20 pounds of chocolate a year! Who wants to emigrate?

Although cacao trees are native to the Americas, 75% of today’s chocolate is grown in Africa (the Ivory Coast is the number one producer). Annual worldwide sales of chocolate total to almost 100 billion dollars. It is estimated that 50 million people around the world depend on chocolate for their livelihoods. Many of these worldwide  millions are poor, subsistence farmers, and the rise and fall of the chocolate industry can have significant impacts on these producers!

In the 1940’s chocolate producers settled on a very select array of cacao trees as their preferred sources of the raw material for chocolate manufacturing. The consequence of this was an increase in the quality and reliability of the raw material for chocolate, but this consistency came at the cost of greatly limiting the genetic diversity of the cacao plantations. The narrow set of cacao clones selected and planted around the world set up a potential catastrophe if some pathogen should attack the narrow resistance base of the trees or if some environmental variable should shift conditions away from the very narrow range of optimal or tolerable conditions of the clones.

And, unfortunately, both of these negative scenarios came about!

Frosty pod rot. Photo by G. Cubillo. Scienta Ricerca Open Access Directory

In the 1970’s cacao trees in Costa Rica were attacked by a fungus (Monliophthora roreri) that causes a disease called “frosty pod rot.”  The impact on Central America chocolate production was sudden and severe (there was a 96% decline in cacao production in Costa Rica which effectively destroyed the chocolate industry there!). The fungus spread through Central and South America and even skipped over to islands of the Caribbean (Jamaica reported frosty pod rot in 2016). The barrier of the Atlantic Ocean did not seem sufficient to prevent the spread of this devastating fungus to the susceptible trees that had been extensively planted in Africa.

Fortunately, there were a few people with forethought and a solid grasp of the potential dangers of clonal chocolate agriculture. In Turrialba, Costa Rica there is an arboretum called the “International Cacao Collection” in which 1235 types of cacao trees are grown. This arboretum houses the great range of genetic diversity of  Theobroma cacao. The arboretum , though, is constantly short of funds (most grants from the large chocolate manufacturers go to research on faster growing, more productive hybrids rather than maintaining this fundamental genetic reserve), and it barely has sufficient means to keep the trees alive and healthy.

Dr. Wilbert Phillips-Mora was the head of the Cacao Genetic Improvement Program at the Tropical Agricultural Research and Higher Education Center in Costa Rica up until his retirement three years ago. Dr. Phillips-Mora was featured last year in a New York Times article about chocolate production (September 25, 2017).

In the 1980’s Dr. Phillips-Mora worked to identify specific types of cacao trees that exhibited disease resistance, including resistance to the frosty pod rot fungus. He painstakingly crossbred and hybridized these disease resistant strains of cacao and finally, after decades of work, developed a handful of hybrids that had both disease resistance and high seed yields but also produced high quality, good tasting chocolate. These hybrids (which produce three to six times more cacao than regular trees) are now being planted all across Central America, Mexico and Brazil.

Photo by Nestle. Flickr.

There are many on-going problems with these hybrids. They do not self-pollinate (and, therefore, do not always breed true), some produce very small beans, and some may have adverse reactions to the arrays of pathogens that are endemic in the wide variety of geographic regions into which the trees are being introduced. These problems, though, are being studied and managed.

After his retirement, Dr. Phillips-Mora stayed on in Turrialba to oversee the International Cacao Collection arboretum. He is dedicated to the preservation of this vital resource in the fight to save the international chocolate industry.

Last Spring there was an article in Penn State News (May 9, 2018) about some other attempts to save the cacao tree. Researchers at Penn State are using the gene insertion tool CRISPR to try to breed cacao trees that will be resistant to disease and also tolerant of the warmer tropical temperatures predicted by global climate change models. These researchers recognize that cocoa production has reached a potential limit with regard to land, water and fertilizer use and that the trees themselves must now be changed in order to maintain or potentially increase the worldwide production of cocoa. CRISPR may enable these researchers to find a tree type much more rapidly than if they were still only using classical tree hybridizations methods.

So here we are in the time of chocolate. There are suggestions, though, that chocolate, like coffee (see “Signs of Spring 6,” March 23, 2017), might not survive our ongoing abuse of our planet. Let’s hope we can stay ahead of changes we are causing and enjoy our mocha coffees (and more!) forever!