Despite quite intensive testing of varieties, predictions of future performance of varieties, when grown on specific locations, are known to be nearly impossible; this especially within organic growing systems, where no pesticides and fertilizers can help stabilize yield. Therefore, using mixtures of appropriate varieties might be a way to obtain more stable and acceptable yields. Variety mixtures have so far been studied mostly under conventional farming conditions and focus has often been to characterize disease progress of one pathogen. Here we consider simultaneously four important foliar diseases on spring barley grown in organic as well as conventional growing systems. Further, we study the changes in disease severity of variety mixtures when adapting to local growing conditions (‘farm saved seeds’ or ‘farm varieties’)
