Pesticide dose is a parameter that is central to pesticide efficacy, effects of pesticides on non-target organisms, evolution of pesticide resistance, and non-intended pesticide effects such as hormesis (the stimulatory effect of a sub-toxic dose of a toxin). This book details and documents the reasons why only a tiny fraction of applied pesticides reach their desired molecular targets in the pests for which they are intended. This is followed by a discussion of the relationship of dose to efficacy levels and the practical implications of this. Pesticide movement to non-target organisms by drift and other processes has become a topic of great interest and is thoroughly covered. The book ends with a review of the effects of herbicides on non-target terrestrial plants with large differences in sensitivities to low herbicides doses. This volume gives the reader an appreciation for the complexity of pesticide dose effects.