These management practices have proven to be useful, effective and worth the efforts for many farmers, but chemical weed control in the long term has to face changing conditions and circumstances. They are used in a constantly changing and adaptive environment, and therefore their effectiveness can vary over time and location. However, the extensive and unsound use of herbicide has resulted in the development of herbicide resistance in several weeds. In addition the launch of herbicides with new modes of action has slowed down considerably (Rueegg et al., 2007). This can partly be ascribed to the consolidation process of the agrochemical industry resulting in less overall research and development infrastructure as in the increased regulatory requirements for registration. In Europe, the review process of pesticides under the Directive 91/414/EEC has additionally narrowed the spectrum of approved herbicidal active ingredients.