Climate change impacts the spread potential of wheat stem rust, a significant crop disease

Long range atmospheric transport is an important pathway for the spread of plant pathogens, such as rust fungi which can devastate cereal crop health and food security worldwide. In recent years, serious concern has been caused by the evolution of new virulent races ofPuccinia graminis f. sp. tritici, a pathogen causing wheat stem rust that can result in close to 100% yield losses on susceptible wheat cultivars in favourable weather conditions. We applied an Earth system model to compare the suitability of the current climate and a business -as -usual climate scenario (RCP 8.5) for 2100 for wheat stem rust. Although there are large uncertainties in modelling changes in disease spread, we focus in this paper on the changes which are likely to be robust to model assumptions. We show that the warmer climate with lower relative humidity and enhanced turbulence will lead to 40% increase in the urediniospore emitting potential of an infected field as global average. The main predicted changes in the atmospheric long-range transport include reduced connections between Europe, Africa and South Asia, and increased frequency of spores crossing the mid-latitude oceans. Due to reduction in subfreezing conditions, the overwintering areas ofthe fungus will expand. On the other hand, projected drier conditions will reduce substantially the probability of an infection starting from deposited spores, except in irrigated fields.