Perennial weeds in organic arable farming – challenges & dilemmas

Long-term control of perennial weeds create a challenge in organic farming, especially in ar-able farming. Perennial weeds are most often controlled by tillage, often stubble tillage after harvest of cereals or short-term tillage during the summer (Melander et al., 2005). Tillage leads to increased leaching of nutrients (Askegaard et al., 2005), which is unacceptable for the environment and in turn renders the succeeding crop less competitive compared to the peren-nial weeds – thus initiating a vicious circle.