Food security (FS) encompasses food availability (production, imports and reserves), physical access (transport, logistics and supply chains), economic access to food (food pricing, economic status of population) and food utilization (food quality and safety), all underpinned by stability. Each dimension may be affected singly or interactively by any of a number of transient (e.g. disease outbreak in one season) or chronic (e.g. endemic diseases) factors. Plant pathogens directly affect production, imports, reserves, food quality and safety. However, many other factors affect FS, such as demographics (urbanization, diet change, ageing and declining farmer population), degradation of the natural resource base (soil and water), declining crop productivity growth, climate change and unsupportive agricultural policies. Ensuring food security therefore requires multi-disciplinary, multi-sectoral approaches to address all four FS dimensions. In tropical regions, diseases have chronically been yield reducing and cause crops not to achieve their yield potential in most years while in outbreak years have disrupted exports. Losses in storage and during processing, transport and retailing account for further threats to the stability of food availability. Microbial effects on food quality and safety, and the use of biotechnology have precipitated international efforts at harmonizing techniques and regulations to address the ‘physical access’ and ‘utilization’ aspects of FS.