Cassava is grown throughout sub-Saharan Africa and increasingly is the main starch staple, particularly in West and Central Africa. An estimated 94×106 t of the tuberous roots were produced in Africa in 2001 with 8×106 MT in Ghana alone Cassava is also a raw material for food industries, livestock feed and a source of starch for chemical industries. However, pests and diseases, particularly cassava mosaic disease, are a major constraint. High-yielding, station-bred, cassava varieties have had limited uptake in much of Africa, including Ghana. The project therefore has two main aims: 1. To develop an effective means of breeding new cassava varieties which are high yielding, pest (particularly cassava mosaic disease) resistant and acceptable to Ghanaian farmers, through involving farmers from the earliest stages of selection. 2. To understand how cassava landraces developed. This is being done by investigating farmer attitudes and practices regarding seedlings and should facilitate farmer involvement in cassava breeding.