7Global food security is strongly determined by crop production. Climate change will not only 8 affect crop yields directly, but also indirectly via the distributions and impacts of plant 9 pathogens that can cause devastating production losses. However, the likely changes in 10 pathogen pressure in relation to global crop production are poorly understood. Here we show 11 that disease risk for 79 fungal and oomycete crop pathogens will closely track projected yield 12 changes in 12 major crops over the 21 st Century. For most crops, yields are likely to increase 13 at high latitudes but disease risk will also grow. In addition, the USA, Europe and China will 14 experience major changes in pathogen assemblages. In contrast, while the tropics will see 15 little or no productivity gains, the disease burden is also likely to decline. The benefits of 16 yield gains will therefore be tempered by the increased burden of crop protection. 17
Main text 18Plant pests and pathogens exert a growing burden on crop production around the world 1,2 . 19The burden can be measured directly in yield losses or indirectly in the social, environmental 20 and economic costs of control 1 . Like all species, crop pests and pathogens have particular 21 tolerances to, or requirements for, particular environmental conditions 3 . These tolerances 22 define their ecological niche, which determines the geographical regions and periods of the 23year that allow pests and pathogens to proliferate and attack crops 3 . As climate changes, 24 suitable conditions for pest outbreaks shift in time and space, altering the threats that farmers 25 face and the management regimes required for their control 4 . Modelling the pattern and 26 process of future changes in pest and pathogen burdens is therefore a key component in Latitudinal range shifts of pests and pathogens are expected as the planet warms and 29 populations track their preferred temperature zones 4 . Spatial movements in geographical 30 distributions and temporal shifts in phenologies of wild populations are among the clearest 31 signs of anthropogenic global warming 6 . Though distribution data for crop pests and 32 pathogens are noisy and incomplete 5 , similar changes have been detected for hundreds a 33 species of pests and pathogens over recent decades 7 . Increasing burdens of insect pests at 34 high latitudes, and decreasing burdens at low latitudes, have been projected using ecological 35 niche models (ENM) 8 . ENMs attempt to reconstruct the environmental tolerances of species 36 from contemporary climates within the observed species range using statistical models 9 . 37Alternatively, species' responses to microclimate can be directly measured, and these 38 responses incorporated into physiologically-based models of species performance 10 . Such 39 mechanistic models are commonly used to project future crop yields 11 , and models have also 40 been developed for some plant diseases 12,13 . However, we know little about how plant 41 disease pressure is likely to change in future, nor h...