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Witches' Broom Control (c 2005)



The CFC-financed project was implemented as a response to an outbreak of witches’ broom disease in the late 80s in Brazil, which led to the drop in cocoa production from 380,000 tons p.a. to 90,000 tons in the late 90s. Due to mass abandonment of cocoa plantations, the area planted under cocoa dropped sharply from 600,000 ha to 300,000 ha within 15 years.



Immense effects due to witches' broom 
An estimated 30,000 farm workers became jobless due to witches' broom in the Brazilian state of Bahia alone. The indirect effects are estimated to have affected another 250,000 people who were dependent on cocoa production and related activities. Purchasing power and living standards in the cocoa producing areas of Bahia dropped measurably, leading to increased urban migration of the affected rural population. A register of inhabitants of rural areas in the early years of the disease outbreak showed a 13% increase, due to intensive efforts aimed at containing the disease.

Mass felling of indigenous trees
Another serious aspect of the witches' broom outbreak was the mass deforestation of indigenous trees, which were used to shade cocoa plantations. To compensate for loss of cocoa income, the trees were now felled and sold as timber and make way for cattle raising or other farming systems. This had negative effects on the Atlantic Rain Forest, which is recognised as having one of the world’s largest biodiversities. 

Aim of the project
The aim of the project was to search for, and rapidly scale up cocoa varieties resistant to witches’ broom disease through the use of molecular marker techniques in order to quickly provide farmers with resistant plants that could replace the old and highly susceptible plants.

It can be seen from available statistical data that in Brazil the project was very successful in rapidly translating scientific results into use in applied cocoa breeding that subsequently led to the release of commercial cocoa cultivars with improved resistance. As a direct result of the project, i.e. the techniques acquired, a total of eleven new clonal varieties have already been released and made available to farmers on a large-scale. 

Another eleven cultivars have been released to date for field observation (small scale), this being the last stage before large-scale release. The new techniques ensure that material released is more accurately evaluated both at phenotypic (production, disease symptoms, etc.) and at molecular level (source(s) of resistance) thus decreasing the risk of failure under field conditions.

The identified resistant cultivars are mass-produced in a large nursery that has been especially built to revitalise cocoa production. So far, about 7 million plantlets have been produced and handed out to approximately 7000 farmers for a nominal fee.

Upward trend in production 
As a direct consequence of the project, per hectare cocoa production has been picking up again since 2000 and total production has again reached 144,000 tons, with a continuous upward trend. 

Today there are clearly visible signs that abandoned farms are being reactivated and the cocoa grinding industry is being revived, leading to reemployment of farm and factory workers. This in turn is reflected by re-migration into rural areas and increased commercial activities in the rural centres. With increased income, remnant forest is not further destroyed for revenue, as it is recognised that the newly introduced cloned cocoa require adequate shade to be productive. 

Situation in Ecuador and Peru
In the other two participating countries, Ecuador and Peru (where small portions of the project funds have been allocated), witches’ broom already first appeared earlier last century (Ecuador 1916 and Peru 1930) and a slow recovery was made over many decades with conventional resistance breeding methods. However, since then, frequent new outbreaks, sometimes favoured through the release of unsuitable cultivars, pose a permanent threat to cocoa production in both countries. 

In both countries, the introduction of molecular marker techniques through the project has led to a regular rapid screening and testing routine during selection and breeding, that has significantly increased the speed of the breeding process and prevents the release of unsuitable cultivars. Both countries have established a good working relationship with the Project Executing Agency (PEA), the Comissão Executiva do Plano da Lavoura Cacaueira (CEPLAC) (Brazilian Executive Commission for the Cocoa Farming Plan) in Brazil that has led to a free exchange of promising germplasm material between the three countries, which will be continued.