In Germany, an interdisciplinary working group Ambrosia has been established in 2005. The group consists of experts in the fields of botany and ecology, plant protection, medicine and aerobiology. It has met annually and strives to reduce the occurrence and the impacts of annual ragweed in Germany. The conference in 2013 was organised on behalf of the interdisciplinary working group and of the consortium performing the EU project HALT Ambrosia. It has shown that the negative impacts of the ragweed invasion in Germany are severe and are likely to increase if no control measures are applied. There is sufficient information about ways to control ragweed in various situations (e.g., road verges, agricultural fields or urban-industrial sites). The fact that the species is still spreading is due not to a lack of information but to lacking implementation of control measures. The chance to halt the ragweed invasion in Germany depends on several factors, among them a clear legal specification for management measures.