A participatory breeding programme involving farmers in two Ghanaian communities and scientists from CRI (Ghana) and NRI (UK) to develop superior cassava cultivars is described. Initial situation analyses of the communities indicated that cassava is increasing in importance both as a food and a cash crop. Most farmers utilised landraces of cassava; modern varieties were scarcely mentioned. Seeds of 16 half-sib families obtained from a crossing block in Nigeria at the International Institute of Tropical Agriculture were planted in a field in each community. During seedling and subsequent clonal generations, accessions selected either by farmers or scientists were retained to the next generation. This selection process has identified 29 superior accessions from amongst 1350 original seedlings. Farmers were relatively consistent in their selection from year to year and their selections corresponded with their stated criteria. Official variety release requires additional multilocational and inspection trials and postharvest assays but otherwise seems harmonious with a participatory breeding approach; our early involvement of farmers may facilitate early release, an important factor in cost-effectiveness. A stakeholder workshop confirmed the need for improved markets for cassava; surveys of current and potential markets have led to field trials with cassava processors. Adoption of a participatory approach, with farmers and scientists taking on new roles and decentralisation of activities, implies a concomitant transfer of influence and resources.

During surveys on anthracnose disease of cassava and yam, farmers were interviewed through questionnaire to seek their knowledge of the disease in four ecological zones in Ghana (Forest, Transition, Guinea Savannah and Coastal Savannah). Results analysed indicated that over 61% of the yam farmers and 79% of cassava farmers have good knowledge of anthracnose diseases. The farmers were aware that the disease occur on the leaves and stems of cassava and also on the leaves and vines of yam. More than 50% of the farmers said that wet seasons are the period where the disease spread most. In all the ecological zones, more than 55% of the farmers indicated that the disease has negative effect on their produce yet more than 60% of the farmers did not have any idea as to the causes of the disease and do not undertake any control method to manage the disease. The work has revealed that farmers may know about diseases due to long periods of farming, their knowledge on the causes and control of cassava and yam anthracnose disease is inadequate and therefore need more education.

A fungus with morphological features corresponding to the group species Colletorichum gloeosporioides was consistently isolated from cassava with shoots showing dieback symptoms in Ghana. When four locally‐grown cultivars were inoculated with isolates of the fungus, they developed disease symptoms, which consisted of discrete dark brown lesions on the stems followed by defoliation. Koch's postulates were completed by re‐isolating the fungus from the inoculated plants. The relatedness of the isolates lo other members of the genus Calletotrichum, whose identities were well established, was investigated by comparison of the nucleotide sequence of domain 2 of their ribosomal DNA. The cassava isolates differed from authentic isolates of C. gloeosporioides by only one nucleotide among the 193 analysed. The causal agent of cassava stem tip dieback (STDB) is thus identified as a form of C. gloeosporioides.

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