Potential effects of global warming on oilseed rape pathogens in northern Germany

Abstract: The rise of mean air and hence soil temperature due to global warming will have effects on both crop and fungal pathogen development. Within the research framework KLIFF (Climate Change Research in Lower Saxony, Germany), potential effects of higher air and soil temperatures on the life cycle of the economically important oilseed rape pathogens Leptosphaeria maculans, Sclerotinia sclerotiorum and Verticillium longisporum are investigated both theoretically and experimentally.Within the theoretical approach, published knowledge about temperature influences on certain life cycle stages of the pathogens, such as survival, sporulation, infection and further disease development, was compared with current climate change scenarios for the periods 2001-2030 and 2071-2100 at three different oilseed rape growing regions in northern Germany. There is evidence that warming might favour all three fungal diseases, but shifts in future prevalence of these pathogens may occur, favouring Sclerotinia sclerotiorum and Verticillium longisporum in particular.In order to study effects of rising soil temperatures on the soil- and debris-borne life cycle stages of the three pathogens under field conditions, a soil warming experiment was established. Investigations include (1) ascospore release of Leptosphaeria maculans in autumn as well as subsequent stem canker development, (2) apothecia production of Sclerotinia sclerotiorum in spring and (3) the infection of winter oilseed rape by Verticillium longisporum. First year experiences and results of this soil warming experiment will be presented, including warming effects on plant growth, microclimate and fungal pathogen development.