The "necessary extent" of pesticide use -: Thoughts about a key term in German pesticide policy

German plant protection law demands farmers to limit the use of pesticides to a necessary extent. In this article, we have developed a theoretical framework on deciding on pesticide use. We look at three different ways of interpreting how much pesticide is "necessary" to control a pest on a crop: (1) using a product at the recommended dose when a pest is found or a precautionary treatment thought necessary, (2) optimising pesticide use for economic savings through adjusted doses, thresholds, etc. and (3) minimising pesticide need by altering the cultivation system to lower the risk of pests. The smallest pesticide use intensity can be reached by combining approaches 2 and 3. In practice, information on optimising pesticide use needs further research to reduce the uncertainty about the effects of agronomical control measures, both with respect to economics and risk. (C) 2007 Elsevier Ltd. All rights reserved.