PHYTOPHTHORA POD ROT AND THE RAGING ENEMIES OF COCOA PRODUCTION IN NIGERIA: A REVIEW

Abstract

Theobroma cacao is of major economic importance to Nigeria and other growing countries across the tropics. Being one of the fastest selling commodities in the world, demand for its beans is very robust. But contrary to what generally operates in the global scene, cocoa production in Nigeria has in recent years decreased, plunging the country to the sixth position in the world production table. The problems of pests and diseases, significant among which is Phytophthora pod rot (black pod), has been said to be hugely responsible for this challenge. Phytophthora palmivora and the highlyvirulent P. megakarya among others, have however been discovered to be major causative agents of the disease, with the latter so far reported only in West and Central Africa. In Nigeria, P. megakaryahas over the years replaced P. palmivora as the main causative agent of black pod disease. The pathogens cause brown to black lesions on infected cocoa pods at every stage of development. Loss due to black pod disease of cocoa is between 20-100% annually. The infection does not only affect the pods, it also spoils the beans. Several measures have been reportedly taken by Nigerian farmers to combat cocoa pod rot, prominent among which is the use of synthetic fungicides. This, though highly effective and reliable when used at recommended dosage, has remained hazardous and expensive. Ineffectively checked proliferation of the pathogen probably due to increasingly high cost of control, has been hugely responsible for the dwindling cocoa production levels experienced in Nigeria in recent years. Long time survival of the pathogen in the soil/debris and climatic factors has made a reasonably significant control of the disease a big challenge to Nigerian farmers. Detailed exploration of the use of botanicals with other safe and affordable techniques would therefore help keep the problems at bay.