Pests and diseases cocoa is host to a large number

PESTS AND DISEASES
Cocoa is host to a large number and variety of organisms, for example, numerous insect
species are known to feed 011 the tree. Others are vectors of fungal and viral diseases,
and new pests are continually being introduced to the region. This emphasises the need
for strict quarantine precautions to limit further spread, The distribution of important pests
and diseases of cocoa are summarised in Table 6.
Modification of Environment
Maintenance of a complete canopy and overhead shade minimises mirid damage. The
incidence of black pod may be reduced by light access pruning to reduce humidity within
the plantation.
Chemical Control
A wide variety of insecticides and fungicides are in use, for instance organochlorines to
contain mirids in West Africa and world-wide application of copper-based sprays against
black pod. Wax poison baits, incorporating an anticoagulant, have proved very efficient in
rat control. The use of toxic compounds requires careful management: personal and
environmental contamination must be avoided, and some pests have developed
resistance after prolonged, exposure to some compounds. Methods of biological control
appear to have had little attention, although certain ant species have been introduced to
drive out mirids and Pantorhytes, weevils.

Unit 6: Production of Plantation Crops 6.58
Selection and Breeding
Some varieties show some resistance or tolerance to some of these pests and diseases,
and these characteristics are likely to be increasingly incorporated into selection and
breeding
programmes.
Harvesting
Like most tropical crops, fruit ripening in cocoa is not confined to a short harvest period.
Pods are borne year round, but most cocoa is harvested in two flushes during the year.
These peak harvest periods may each last about three months. Pods are suitable for
harvesting for a period of 2-3 weeks; beans from unripe pods give a poor ferment, while
over-ripe beans may germinate in the pod. Cocoa is often harvested fortnightly, although
weekly harvests may be undertaken during the main flush period to minimise losses to
pod rots and animals.
In harvesting, pod stalks should be cut with a sharp blade. Care is required to avoid
damaging the flower cushion, as future flowers and pods will develop at these sites.

Unit 6: Production of Plantation Crops 6.59
CONCLUSION
Cocoa is an important crop in many tropical countries where it provides a supplementary
income for subsistence farmers and makes an important contribution to the national
economy. The agronomy of cocoa is 'perhaps more complex than of most other crops.
Variation in cocoa response is increased by wide genetic variation within as well as
between varieties and by the complex interacting effects of shade on nutrition, growth and
production.
References
Allen, J.B., and R.A. Lass. 1983. London cocoa trade Amazon project: final report phase
1.