Global change

Abstract

Abstract Accelerating patterns of land-use change, air pollution, global trade, and climate change all contribute to changes in plant-pathogen interactions and the emergence of novel infectious plant diseases. Land conversion to agriculture has led to new encounters between crops and local pathogens, leading to the emergence of novel diseases through spillover. Habitat fragmentation may change patterns of pathogen spread through plant populations. Air pollution and resulting acid precipitation and nitrogen deposition are associated with changes in the types, prevalence, and severity of plant diseases. Globalization, trade, and travel drive the accelerating introduction of new plant and pathogen species into all regions of the globe, creating scenarios for the emergence of novel plant–pathogen interactions. Some destructive epidemics of novel pathogens have had transformative effects on wild plant communities and critical agricultural crops. Chestnut blight, Sudden oak death, and Phytophthora (Jarrah) dieback are iconic examples of these transformative epidemics. Plant pathogens can also play roles in the emergence of invasive plant species, if introduced plants leave important pathogens behind in their native range (enemy release), or if local pathogens attack naïve introduce plants and prevent them from invading (biotic resistance). In biological control, plant pathogens are used intentionally to limit the spread of invasive plant species. Climate change is affecting temperature and precipitation, along with elevated CO2 levels. In turn, these changes affect plant and microbe physiology, phenology, and geographic ranges. Species distribution models and process-based models can help inform predictions about how plant–pathogen interactions will respond to climate change.