Climate change, biotic yield gaps and disease pressure in cereal crops

Plant diseases are major causes of crop yield losses and exert a financial burden via expenditure on disease control. The magnitude of these burdens depends on biological, environmental and management factors, but this variation is poorly understood. Here we model the effects of weather on potential yield losses due to fungal plant pathogens (the biotic yield gap, Y gb ) using experimental trials of fungicide-treated and untreated cereal crops in the UK, and project future Y gb under climate change. We find that Y gb varies between 10 and 20 % of fungicide-treated yields depending on crop, and increases under warmer winter and wetter spring conditions. Y gb will increase for winter wheat and winter barley under climate change, while declining for spring crops because drier summers offset the effects of warmer winters. Potential disease impacts are comparable in magnitude to the effects of suboptimal weather and crop varieties.