title: Management of invading pathogens should be informed by epidemiology rather than administrative boundaries.
abstract: Plant and animal disease outbreaks have significant ecological and economic impacts. The spatial extent of control is often informed solely by administrative geography - for example, quarantine of an entire county or state once an invading disease is detected - with little regard for pathogen epidemiology. We present a stochastic model for the spread of a plant pathogen that couples spread in the natural environment and transmission via the nursery trade, and use it to illustrate that control deployed according to administrative boundaries is almost always sub-optimal. We use sudden oak death (caused byPhytophthora ramorum) in mixed forests in California as motivation for our study, since the decision as to whether or not to deploy plant trade quarantine is currently undertaken on a county-by-county basis for that system. However, our key conclusion is applicable more generally: basing management of any disease entirely upon administrative borders does not balance the cost of control with the possible economic and ecological costs of further spread in the optimal fashion.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
authors.forename: Robin N
authors.initials: RN
authors.lastname: Thompson
authors.affiliation: UC Davis Department of Plant Pathology, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Cobb
authors.affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Gilligan
authors.affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
authors.forename: Nik J
authors.initials: NJ
authors.lastname: Cunniffe
keywords: Economics of disease control; Mathematical modeling; Phytophthora ramorum; Plant disease management; Plant trade quarantine