Impact of Eradication Programs on the Temporal and Spatial Dynamics of Plum pox virus on Prunus spp. in Pennsylvania and Ontario, Canada

The goals of this research were to quantify the impacts of the Pennsylvania and Ontario Plum pox virus (PPV) eradication programs on the spatial and temporal dynamics of PPV epidemics on Prunus spp. The incidence of PPV-positive trees detected over time decreased in both Pennsylvania (−ln 0.85 units per year) and Ontario (−ln 0.51 units per year); however, PPV incidence per year decreased only 60% as fast in Ontario as in Pennsylvania. Marked point pattern analysis revealed that PPV-positive Prunus blocks in Pennsylvania were clustered for distances of 0.7 to 4.3 km, whereas PPV-positive blocks in Ontario were clustered for distances of 1.0 to 25.0 km. Multiyear spatiotemporal analyses revealed that the locations of PPV-positive blocks detected were spatially dependent upon the locations of PPV-positive blocks detected during the previous year. In Pennsylvania, between 2002 and 2006, distances to 95% of newly detected PPV-positive blocks occurred within 10 and 20 km from the previous year’s PPV-positive b...