Transferring new disease management techniques to traditional farmers, or old techniques to industrial farmers, has never been straightforward. A theory-based mechanistic approach is developing that may allow more effective design of disease control than strategies using empirical approaches alone. Most ecological work has been performed in natural communities, which for our purposes means communities not significantly managed to supply a product. Review literature on disease in natural communities generally suggests that disease levels are consistently low and that epidemic outbreaks are rare. In natural plant populations, the interaction between plant density and disease dynamics has been difficult to assess. Studies of disease in established systems of nonnative, naturalized plants may or may not be considered natural systems in ecological balance. An ecological understanding of agricultural pathosystems is being used to analyze and optimize existing elements of control techniques, such as gene deployment, suppressive soils, and crop rotations.