Cassava (Manihot esculenta Crantz, Euphorbiaceae, 2n = 36) is a perennial root crop in the tropics. Its starchy storage roots provide a source of staple food and livelihood for over 600 million people worldwide. Cassava grows in large tropical and subtropical regions of Africa, Asia and Latin America. An average of 10 tonnes per hectare of cassava roots can be produced in a 12 month growing season. The annual world production of cassava in 2002 was 180 million metric tonnes from 16.9 million hectares. Of the total production, Africa, Asia and Latin America account for 54%, 28% and 18% respectively (1). In sub-Saharan Africa, cassava provides up to 60% of the daily calorie intake with more than 80% of the harvest used as food (2, 3). In certain regions, the leaves, which contain appreciable quantities of protein and vitamins, are also consumed as a major component of the diet to provide supplementary protein, vitamins and minerals. Cassava is a key component of food security in developing countries and especially in Africa, where the food insecurity is the most severe in the world (4).