Farmers' information on sweet potato production and millipede infestation in north-eastern Uganda. I. Associations between spatial and temporal crop diversity and the level of pest infestation

Sweet potato (Ipomoea batatas (L.) Lamk) is an important staple food for the people of north-eastern Uganda. Crop yields per unit area are low partly because of biological constraints, including pests like millipedes. The objective of this study was to generate information on pest incidence and control strategies of millipedes by interviewing farmers in different districts. The respondents associated the dying of planting material with drought. However, millipedes also damaged planting material planted early in the rainy season. The sweet potato butterfly (Acraea acerata, Lepidoptera: Nymphalidae) was present, but considered by farmers to be insignificant. Measures to control sweet potato pests, like sanitation, were hardly implemented and insecticides were not used at all. Most respondents performed piecemeal harvesting. Whenever farmers delayed the harvest, they risked severe damage of their sweet potato crops by weevils (Cylas spp., Coleoptera: Curculionidae) and millipedes (Diplopoda). Millipedes pierce and tunnel the storage roots, especially when harvesting is delayed. The farmers did not mention specific natural control agents for millipedes. Knowledge about pests was generally limited, so control strategies were poorly developed, understood and applied