Pests and diseases of cocoa
High levels of yield loss to pests and disease is a major problem for world cocoa production. The diseases of major economic significance are listed in Table 1 below with an estimate of the annual production losses attributed to each. This list is not exhaustive and there may be others of lesser, but still notable importance.
|Disease||Region||Estimated World Production Loss(tonnes)|
|Black Pod (phytophthora fungus)||Africa, Brazil, Asia||450,000|
|Witches Broom (fungus)||Latin America||250,000|
|Frosty Pod Rot (fungus)||Latin America||30,000|
|Swollen Shoot Virus||Africa||50,000|
|Vascular Streak Dieback (virus)||Africa||30,000|
Though over 1500 different insects are known to feed on cocoa, only about 2% are of economic importance. However, when cocoa is introduced into a new area, a previously unrecorded pest almost invariably attacks it. Mirid bugs such as Helopeltis are the most significant and widely occurring insect pests of cocoa, and the cocoa pod borer is a major pest in Malaysia and Indonesia. Mealy bugs are generally not a major pest themselves, but are a well known vector for viruses of cocoa.
In the wild, natural sowing of cocoa relies on animals such as rats and monkeys breaking into ripe pods and feeding on the sweet mucilage around the beans. Significant yield losses from such damage are experienced in almost all parts of the world where cocoa is grown and may well be 5-10% on average.
Common insect pests include:
- Broad mite
- Flower-eating caterpillars
- Yellow peach moth
Weed control is mainly an issue during establishment. Traditionally young cocoa is weeded by manual slashing along the tree rows or around young plants. More recently, herbicides have also been used. When cocoa is mature and a complete canopy is formed, heavy shading and leaf mulch inhibit weed growth so that only occasional attention to removing woody weeds is required. Weeds will be an issue wherever the canopy allows light to penetrate or there are aisles provided for access.
- Growing cocoa
- Commercial viability of cocoa
- Wood , G.A.R. and Lass, R.A., 1992. Cocoa. Tropical Agriculture Series, Fourth Edition. Longman Press, London.
- Infopest (database of chemicals registered for agricultural use)