Climate change and arable crop disease control: mitigation and adaptation.

Global food security is threatened by crop diseases that account for average yield losses of 16%. Climate change is exacerbating the threats to food security in many areas of the world, emphasising the need to improve crop yields to increase food production in northern European countries such as the UK. However, to mitigate climate change, the crops must be grown in such a way as to minimise greenhouse gas emissions (GHG) and optimise inputs associated with their production. As examples, it is estimated that UK production of winter oilseed rape and winter barley is associated, respectively, with GHG of 3300 and 2617 kg CO2 eq. ha-1 of crop, with >70% of the GHG associated with the use of nitrogen fertiliser. Furthermore, it is estimated that control of diseases by use of fungicides in UK oilseed rape and barley is associated, respectively, with decreases in GHG of 100 and 50 kg CO2 eq. t-1 of seed. These results demonstrate how disease control in arable crops can make a contribution to both climate change mitigation and sustainable arable crop production. Climate change will affect both growth of agricultural crops and diseases that attack them but there has been little work to study its combined effects on crop-disease interactions to guide strategies for adaptation to climate change. For example, it may take 10-15 years to develop a new fungicide and it is important to identify future target diseases now. As examples, the impact of climate change on UK epidemics of phoma stem canker and light leaf spot on winter oilseed rape and fusarium ear blight on winter wheat is investigated by combining weather-based disease models, crop growth models and simulated weather for different climate change scenarios. It is predicted that climate change will increase the risk of oilseed rape phoma stem canker and wheat fusarium ear blight epidemics but decrease the risk of light leaf spot epidemics by the 2050s. Such predictions illustrate unexpected, contrasting impacts of climate change on complex plant-disease interactions in agricultural and natural ecosystems. They can provide guidance for government and industry planning for adaptation to effects of climate change on crops to ensure future food security.