Witches’ broom (WB)

Causal agent Moniliophthora perniciosa is present in South America and the Caribbean and infect cocoa stems, branches, flower cushions and pods causing multiple symptoms, but the most recognisable are the brooms on the branches and pink basidiocarps on dried brooms. 

Losses can range from 50-90% in the most severely infected areas. 

The deliberate introduction of the disease into Bahia, Brazil in 1989 resulted in cocoa production falling by more than 50% within 10 years, the economic and social results were devastating for the region.
 

• The disease is spread through spores produced in the canopy from fruiting bodies that develop on the dried brooms. The spores can move long distances but spread has been associated with movement of infected plant parts i.e. budwood, unlike frosty pod rot (FPR) the disease has also been reported to be seedborne.
• The best combination for management is through a combination of phytosanitation and planting resistant/ tolerant material. Pruning of the infected dry brooms is carried out during the dry season, and the pruned material should be removed from the field and destroyed to prevent the development of the fruiting bodies and reinfection.
• ‘Hidden brooms’ are difficult to remove so trees should be kept well pruned and a manageable height to facilitate phytosanitary pruning.
• Fungicides are not normally recommended for management of WB, due to the difficulty of targeting multiple infection sites. Trichoderma stromaticum is a biocontrol option developed and marketed by CEPLAC, to be sprayed onto the pruned dry brooms to reduce the production of the fruiting bodies in the field.