Differences in perceptions and knowledge of crop diseases constitute a major obstacle in farmer–researcher cooperation, which is necessary for sustainable disease management. Farmers’ perceptions and management of crop diseases in the northern Ethiopian Regional State of Tigrai were investigated in order to harness their knowledge in the participatory development of integrated disease management (IDM) strategies. Knowledge of disease etiology and epidemiology, cultivar resistance, and reasons for the cultivation of susceptible cultivars were investigated in a total of 12 tabias (towns) in (...) ten weredas (districts). Perception of diseases involved both scientific and spiritual conceptual frameworks. Of the more than 30 crop diseases recorded on the major crops in the region, only rusts and powdery mildews (locally called humodia) and a few root rots were considered by farmers to be important. Farmers’ awareness of other diseases was extremely low; some highly damaging but less conspicuous diseases, such as faba bean chocolate spot and chickpea ascochyta blight (also called humodia), were not regarded by farmers as disease but as problems caused primarily by excessive soil moisture. Considering that some of these “unrecognized” diseases can cause complete yield loss and genetic erosion in epiphytotic years, there is an urgent need for bringing together farmers’ and scientists’ knowledge to complement each other. Even when farmers had access to disease-resistant or disease-tolerant cultivars, they grew susceptible local varieties because of multiple criteria including earliness, good yield in years with low humodia severity, suitability for home consumption, market demand/quality, and low soil fertility and land management requirements. Farmer innovation and knowledge were evident in their use of diverse disease control measures, but these were a mixture of the “useful and the useless.” Our findings stress the necessity for extension workers and researchers to understand and improve farmers’ knowledge of crop diseases, and farmers’ ability to observe and experiment, through the Farmer Field School or a similar experiential learning approach. These insights about farmers’ knowledge of crop diseases provide a basis for further collaborative maintenance of crop genetic diversity, development of germplasm, and IPM-related research in Africa. (shrink)