Some Background on Cocoa Pests and Diseases

Throughout the blog, I have mentioned the fickle nature of the cocoa tree. It is prone to diseases and a ready target for various pests. These become especially pronounced when the trees age and when farms are replanted. Many of the articles I cite as sources for my posts also mention these problems. So here’s a run down on the most common problems the cocoa tree faces.

The information below is taken from the Ohio State University Integrated Pest Management web site and from a website organized by R. Bateman of the Imperial College in London. One caveat: the latter website is advocating for the use of pesticides and supported by the big names in the industry. In no way do I advocate for or endorse  the purpose of that website.

Black Pod

Black pod disease
Black Pod Disease

Black pod disease is a fungal disease that affects cocoa trees world wide. Once infected, a pod is no longer useful. It is difficult to control and probably responsible for the largest economic loss. It is thought that high humidity contributes to its outbreak and reducing humidity is considered one strategy to control its outbreaks.

Recent reports of a rainy beginning to the new cocoa season in the Côte d’Ivoire indicated that the heavy rains had contributed to black pod disease. However, the rains have since stopped and the incidents of disease seem to be under better control.

Witches Broom

Witches Broom

Witches broom affects cocoa plants in Latin America. First discovered in the Amazon region, it is now present in all major cocoa growing areas in Latin America. It’s impact has been particularly strong in Brazil where it has reduced cocoa production by over half.

Aggressive pruning during the dry season can be an effective means to control witches broom to prevent spores from migrating during the rainy season.

Monilia Pod Rot

Monilia Pod Rot
Monilia Pod Rot

Monilia is a fungal disease that is at the moment limited to certain areas of Latin America. The only proper precaution is to remove infect pods as soon as possible. Fortunately, the infection is easy to spot. However, if pods remain on the tree too long, spores will develop on the surface and spread to other pods.

The difficult of managing this disease is the frequency with which the cocoa farms have to be monitored. The time window for removal of infected pods is twelve days after which the spores begin to spread to other pods.

Frosty Pod Disease
Frosty Pod Disease

Frosty Pod Disease

Frosty pod disease was first discovered in Ecuador and has since migrated to other cocoa producing countries in Latin America. It produces many spores which migrate easily to other pods and trees. It as been identified as a close relative to the spores causing Witches Broom.

It has a high potential for spreading and is thought of as a very serious threat to cocoa production in Latin America.

Mealybugs spread Swollen Shoot Disease
Mealybugs spread Swollen Shoot Disease

Swollen Shoot Disease

This disease is the curse of West African cocoa production. It has wiped out many a crop in Nigeria and Ghana.

What is to be done?

There is a massive effort, sponsored in large part by the chocolate industry but also by research institutions and the various cocoa boards in producer countries to control and overcome these and other diseases. The current method relies on the extensive use of pesticides and fungicides. However, with the recent adoption of new guidelines by the European Union limited the levels of pesticide residue in cocoa, that approach has its limits. Besides, we know that bacteria, fungi and viruses quickly adapt to pesticides and become even stronger.

There are efforts to breed new strains of cocoa trees that are disease resistant. But history again shows that the diseases catch up with these efforts as well. There is genetic modification but we don’t even know what that’s going to bring.

Finally, there are the never ending efforts to teach farmers how to grow cocoa properly. This idea of European an North American development “experts” is as old as cocoa production in Africa. Gareth Austin has documented in a neat chapter published in Clarence-Smith’s Cocoa Pioneer Fronts how the British tried to teach Ghanaian farmers how to properly deal with pests and diseases during the 1920s and 1930s.

Some of these recommendations sound suspiciously like the recommendations offered today: space trees properly, weed regularly, cut down and remove diseased trees, etc. However, Austin’s research showed that when it came to dealing with the Capsid bug at least, the farmer’s method of “weeds overgrown” worked best. They simply let the infected areas lay fallow for three years and then cleaned it back up and the Capsid was gone.

I wonder if the people behind the current efforts read history. In any case, farmers are inevitably rational decision makers. They organize their cocoa farms in ways that suit their available labor and the prices they expect to receive. Offer better prices and farmers will put more effort into their trees. It’s not really that difficult to understand.

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One Reply to “Some Background on Cocoa Pests and Diseases”

  1. mealy bug attack is severe. please suggestions given for control properly. in my coconut garden we grow cocoa as inter crop. i get hardly 3 lakhs Indian rupees from 8 acres. but last year i faced lot of trouble with mealy bugs. 1 lakh rupees loss was observed.

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