Researchers worked with a group of farmers in Southern Malawi to find out what farmers know about witchweed (Striga asiatica), the sweet potato weevil (Cylas puncticollis) and the beanfly (Ophiomyia spp.) and how this affects the ways in which a control programme could be implemented. Although some relationships between pest problems and other factors such as soil fertility were generally well recognised by the farming community, the farmers contacted by this project lacked some of the detailed biological and ecological knowledge that is necessary for an understanding of why,certain control practices are necessary. These gaps in their understanding have a direct bearing on farmers' current approaches to control. The authors conclude that providing farmers with this information is essential if the control technologies being developed are to be sustainable.