Amplifying plant disease risk through assisted migration

Translocation of species, populations, or genotypes beyond their historic ranges (i.e., assisted migration [AM]) is an oft‐debated climate adaptation strategy. Well‐intentioned AM actions could alter disease dynamics for target species and recipient sites, resulting in unanticipated detrimental economic and ecological impacts. Although disease risks are occasionally mentioned in AM debates, current regulations or best practices that reduce or mitigate these complex risks are generally lacking in North America. We use the “Disease Triangle”, a foundational framework in pathology, to illustrate pathways through which AM may impact disease emergence, to identify knowledge gaps, and to suggest best practices to reduce disease risks. We highlight empirical examples in which altering pathogen distributions, host communities, and environment have historically resulted in costly and ecologically damaging diseases in plants. Although guidelines to reduce disease risks in AM are generally lacking, policies governing endangered species, invasive species, and disease management can provide starting points for a more comprehensive policy. We use examples from the United States to identify key strengths and weaknesses that can inform regulations to reduce disease risks associated with AM. We argue that consideration of disease motivates policy development that incorporates improved risk assessments, agency coordination, and accountability mechanisms.