Theobroma Cacao – The Need for Hybridisation

by Melissa Cotterell

World demand for chocolate is still growing, with new markets opening up in China and the Far East and demand expected to increase by around 25% within the decade. The cacao industry is unable to cope as it stands at present, with outmoded farming practices and lack of disease and pest-resistant hybrids taking their toll. While for many years small producers have struggled to eke out a living from cacao farming, the industry is just beginning to adapt to the changing face of cocoa farming by the development of sustainable practices.

The Origin of Cacao

Cacao originated in the Americas and spread throughout the globe to Africa and South East Asia. The tree grows only in the tropical and sub-tropical belts of the Equator, although there are regional differences in the cocoa produced due to climate and soil. Venezuelan cacao is perhaps considered the best in the industry, although the majority of the world’s cacao crop is produced in Ghana and the Ivory Coast. Colombia is pushing its cacao industry to become a major export. Cacao has been identified as a viable high cash flow crop to replace illicit drug cultivations in Colombia and elsewhere in South America.

Varieties of Tree

There are four main varieties of cacao: Criollo, Forastero, Trinitario, and Nacional. The Criollo is typically low cropping, but of excellent quality and the beans from this tree are often used in a blend for the production of chocolate. The Forastero is the most common variety in the industry, producing around 80% of the world’s annual output. This variety is favoured due to its high yield and rapid growth, as well as resistance to disease. The Trinitario is a hybrid of the Criollo and Forastero, predominantly cultivated in Central and South America, as well as in Asia. The Nacional is vulnerable to disease and more difficult to cultivate, but has a much sought-after aroma.

Pests and Disease

The cacao industry is subject to a number of different pests and diseases, which has lead to losses of up to 30-40% of global production each year. Heavy research has been devoted to minimizing this damage by extensive study into zoology and identifying animals such as the Capuchin monkey, who like to eat the soft pulp surrounding the cacao seeds from which we produce chocolate. The seeds themselves are poisonous to animals due to their theobromine content and are rejected in favor of the sweet flesh. Theobromine is an alkaloid from the same family as caffeine, contained in the cocoa butter from which chocolate is made. For this reason, commercial crops do not suffer damage from animal foraging in the same way that other crops such as fruit crops might.

It is the damage from the infestation of different varieties of rot and fungi, as well as insects such as the Cocoa Moth, which are responsible for the problems in cacao plantations worldwide. Cocoa mirids bore into cocoa stems, pods and branches, killing the cells they enter, which then produce necrotic lesions. Mirid infestations on shoots frequently cause destruction on the tree as the terminal shoots and leaves die. They prefer trees which are growing in sunlight, although once they have colonized they will spread into trees which are shaded. Insecticide use is common, although interplanting with indigenous plant species, which the pest finds suitable as a host, combined with reduced use of insecticide to allow other insects to prey on the mirids allows for biological control. The Cocoa Pod Borer (or Cocoa Moth) caused widespread losses in the industry during 1890’s and 1900’s. This pest now affects virtually all cocoa producing areas in Indonesia, which has led to decreased production in Malaysia. Although pesticides are effective in controlling this pest at sustainable levels, the high cost of spraying makes this type of control nonviable.

 Witches Broom disease is a fungal infection, which spread throughout the cocoa-producing regions of South America, Panama and the Caribbean. The losses sustained by the industry have perhaps been heaviest in Brazil, where for a decade the Bahia region suffered a 70% loss of production. Although some Trinidad hybrids were developed in the 1950’s which showed resistance to the disease, more aggressive strains of the pathogen from other regions has made these hybrids ineffective. Frosty pod rot is prevalent throughout the Latin American cacao region, causing significant losses and leading to the abandonment of farms. All cacao species appear vulnerable to this disease.  

Black Pod Rot (Phytopthera) has three fungal species of the same genus: P. palmivora, P. megakarya, and P. capsici. P. palmivora and is responsible for global crop loss of around 20-30%; P. megakarya is the most aggressive of these three pathogens, most prevalent in Central and West Africa; while P. capsici is widespread throughout both Central and South America, where it causes significant losses. Vascular-streak die back decimated mature plantations in Papua New Guinea during the 1960’s and has since spread through South East Asia, where it continues to cause major losses.

Cacao Genome Sequenced

At the end of the first decade of this century, an international team led by Claire Lanaud of CIRAD sequenced the DNA of the Criollo variety of Theobroma cacao, identifying a variety of gene families which it is hoped will contribute to the improvement of the cacao tree and fruit – whether by improving growth and crop yield or by enhancing resistance to disease and pests.

Development and Distribution of Resistant Varieties

Through projects such as Cocoa Productivity and Quality Improvement: A Participatory Approach, a number of high-yielding and resistant varieties of cacao have been released to farmers, while research continues into new and improved cocoa planting materials for future release. This global project has been successfully implemented in 13 different countries.

Approximately 2,000 farms across ten different countries were surveyed, with around 2,000 trees identified by the farmers as resistant being of interest due to their high resistance to disease and infestation, or for their high crop yield. Out of these, about 1,500 farm selections had in-situ observation plots established, or had on-farm trial plots set up across 8 countries. The genetic diversity of several thousand farm selections in Africa were analyzed, showing great genetic variation in farm populations, which are of mainly hybrid origin (with important contributions of the Amelonado, Trinitario and Upper Amazon parental genomes).

The project established approximately 240 on-farm selection plots, with varieties selected by breeders being compared with farm selections (clones or seedling progenies). The number of plots has since declined through farmer neglect or drought to around 120, which are still being observed. A number of new varieties have already been selected or confirmed for distribution to farmers, while others have been selected for ongoing trials in other cacao growing regions.  New variety trials have been implemented in: Brazil; Ivory Coast; Ecuador; Colombia, Malaysia; and Papua New Guinea.

The Challenges of Creating a Botanical Garden

Bixa orellana is a typical medicinal and alimentary tree.

If you had asked me 10 years ago whether I would ever create a botanical garden, I probably would have laughed at the idea. How times have changed! I have always been passionate about medicinal plants, but I never really thought about what that involves in a reforestation setting. Worse, it never really occurred to me that there are numerous tree and plant species that are endangered, and that losing them means possibly losing the cure for a serious disease. As I got more and more involved with tree planting and conservation in the Orinoco River basin, I realized that numerous trees there have amazing medicinal and alimentary properties. It is sad to note that our knowledge regarding those rain forest trees is being lost, as the use of big-pharmaceutical chemical drugs replaces traditional wisdom of natural cures and therapies around the world.

The selected site is 16 hectares or 40 acres in size.

Thanks to our conservation work with the establishment of the Reserva Natural La Pedregoza, I came into contact with analog forestry folks who told me about an interesting program being coordinated by the Missouri Botanical Gardens in the United States. They are actively looking for partners around the world who will establish botanical gardens dedicated to the preservation and conservation of traditional medicinal and alimentary trees and plants. The more I thought about it, the more I loved the idea. I discussed it with my co-founders at La Pedregoza, so we contacted the Missouri Botanical Gardens, and with their blessing and support created the Sacred Seeds Botanical Garden at La Pedregoza. 

The Sacred Seeds garden is backed by a gorgeous morichal.

  

Never having built a botanical garden before, I wasn’t completely sure how to start. The first thing we did was look for a suitable site within the Reserva Natural La Pedregoza. One site in particular looked like it offered a wide range of features ideal for the proposed garden. It had terrain that included low lying areas, well-drained areas, areas that inundate, serranía (the local rocky hills that dot the Orinoco River basin), all bordered by one of our fabulous morichals. We agreed that we had found the site for our Jardín Botánico de Semillas Sagradas (Sacred Seeds in Spanish) project. I called up a civil engineer and surveyor in Puerto Carreño and asked them to come out and create a topography and lot plan for the proposed botanical garden. A short time later we had a topographic plan in 25 cm elevations that covered a whopping 16 hectares or 40 acres. Somewhat stunned by the size of what we were about to do, a friend of ours joked that we were going to be busy for the next 20 years.  

Anandenanthera peregrina is a ceremonial

 tree in traditional medicine.

Armed with the topography plans, we contacted someone we knew in Edmonton, Canada, who had won an environmental prize for landscape design. Arinna Gritanni agreed to come to Colombia for 2 months as a volunteer and worked on a design for the Sacred Seeds garden. She arrived in January of 2013, and within 6 weeks had a design we liked. The plans feature a nice layout for the botanical garden that includes a camping area for school children, a visitor’s center with seed bank, a board walk through the morichal, a tree nursery, paths, waterways and more. Now we were ready to start thinking about what all to plant.

 

L-R: Dexter Dombro, Oscar Forero Azabache, 

Francisco Antonia Castro Lima, Dr. Kochurani Dombro, 

Arinna Gritanni and Sabine Kotzbauer

I wanted local indigenous participation in the project. Several tribal members told me that they were quite concerned with the fact that their young people are losing the traditional knowledge of the trees and plants, thinking that all medicine comes from a pharmacy and all food from a supermarket. As shamans and elders die the traditional wisdom and knowledge is being lost. I was referred to Francisco Antonio Castro Lima, a renowned indigenous botanist and agronomist from the Amazon region of Colombia, who is also considered one of the foremost botanical experts on Orinoco River basin flora. Francisco agreed to act as a consultant, and has provided an entire nursery of native medicinal and alimentary trees he started for us in Villavicencio.

Ocotea cymbarum seeds collected by La Pedregoza staff.

At the same time I have been verifying which medicinal and alimentary trees are native to the Orinoco. We have been collecting their seeds and germinating them in the tree nursery at La Pedregoza. At present it looks like we will have some 60 species of trees and palms that are medicinal or alimentary, which we can plant in the Sacred Seeds garden, though some species are endangered and getting seeds for many species remains a challenge. Financing is also a big issue. I discussed the project with Maxime Renaudin of Tree-Nation, when he visited the La Pedregoza plantation in January 2013. Both he and his wife Amparo were taken by the idea of a Sacred Seeds garden. Next thing I knew we had Tree-Nation backing, which is a tremendous help in making this project a reality. I can now say that we are truly well on our way to creating an amazing botanical garden with a unique focus, one that will benefit all of humanity.

 

Irrigation water tank at Reserva Natural La Pedregoza.

Where do we go from here? 2013 is a great year so far.  A. Raymond Corporate North America, Inc. has donated 4 solar water pumps to the Reserva Natural La Pedregoza, which will allow us to irrigate among other things the plants in the Sacred Seeds garden, using a well we are perforating for that purpose. I would like to take this opportunity to thank them for such a wonderful donation. I know that they were inspired by the concept of conserving traditional medicinal and alimentary plants, regardless of the location. Now we are going the get busy, start implementing the design plans and, of course, plant trees on site. I am excited about the fact that we are also including palm trees in this process, as many species of palms play important roles in traditional medicines and foods. We continue to receive offers of specialized volunteer labor and useful donations. One of the best aspects of this is just how many people not only see the need for such gardens, but are willing to help in whatever way they can to make our Sacred Seeds Botanical Garden at La Pedregoza a reality.