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

This review analyses potential effects of global warming, i.e. higher mean temperatures, on the life cycle of five economically important oilseed rape pathogens in Northern Germany using a meta-analytical approach. First, the currently available but strongly fragmented knowledge about temperature influences on individual life cycle stages of the referred pathogens, such as survival, sporulation, infection and disease progress is summarised. These data are compared with current regional climate projections (REMO model) based on emission scenario A1B for the periods 2001–2030 and 2071–2100 in three different oilseed rape growing regions in Lower Saxony, Germany, using a baseline historical series of meteorological data collected from 1971 to 2000. Our analysis suggests that warming might lead to shifts in the future prevalence of these pathogens. Verticillium longisporum, Sclerotinia sclerotiorum and Alternaria brassicae could be particularly favoured, but beneficial effects may also occur for certain life cycle stages of Phoma lingam, such as infection and stem canker development. Pyrenopeziza brassicae might even lose importance under future warming. These changes may be particularly explicit in the long-term view (2071–2100). However, predictions on potential disease shifts are restricted by a lack of reliable, high-resolution future climate scenarios and complicated by the prospective adaptations of farming techniques and crop genotypes to climate change.