Connectivity in the landscape affects how pests and disease spread, for humans and crops alike. In agriculture, the spread of airborne pathogens is often assumed to happen via spores that are ubiquitous in the environment. This assumption, though, may misrepresent future growing seasons of a crop when the presence of inoculum varies across both environmental and geographic space. Climate change is likely to affect airborne disease spread both directly, through changes in wind patterns and atmospheric turbulence, and indirectly, by affecting crop growth and crop phenology. So what exactly is the risk posed by airborne pathogens under climate change?
Using a model system of Phytophthora infestans (the causal agent of potato late blight) in Scotland, new research focuses on how climate change will affect the connectivity, phenology, and growth pattern of the host crop (potatoes), as well as the risk of infection by late blight. The impacts of climate change on the spread of disease throughout a connected agrosystem is applicable to not only potatoes, but many other globally important crops, and understanding these impacts can help inform management decisions.
By modeling multiple combinations of potato cultivar and CO2 emissions scenarios, the study found several key results:
- Crop connectivity for P. infestans inoculum is projected to greatly increase during the first half of the growing season under all future CO2 emissions scenarios, and decrease during the second half of the season. These changes in connectivity have a far greater impact on disease spread than any change in the risk of infection.
- Climate change will likely cause shifts in the phenology of the crop growing season. Advancing the start and end dates of the growing season by 1 month served to decrease future crop connectivity during the first half of a growing season and increase future crop connectivity during the second half, representing a viable management strategy.
- There was great geographic variability in the response of crop connectivity for P. infestans inoculum to climate change, although this is ultimately a mixed bag for management: shifting crops to areas where the disease is least likely to spread under climate change puts them in the same areas where potato production would be most inefficient.
Skelsey, P., D. E. L. Cooke, J. S. Lynott, and A. K. Lees. 2016. Crop connectivity under climate change: future envrionmental and geographic risks of potato late blight in Scotland. Global Change Ecology. DOI: 10.1111/gcb.13368.