Using ‘sentinel’ plants to improve early detection of invasive plant pathogens
Fig 2
The baseline case–the model in the absence of sentinel plants.
A. Schematic illustrating how crop plants progress through the model compartments, and the rates at which transmissions occur. Individual hosts begin in the Healthy compartment (HC), move to the Undetectable compartment (UC) upon infection and progress to the Detectable compartment (DC) once visual symptoms develop. A Detectable crop infects Healthy crops at per capita rate βC whilst an Undetectable crop generates infections at the scaled per capita rate εCβC. B. Schematic illustrating the implementation of the monitoring programme. Monitoring begins at a random time δ relative to the time of primary infection, where δ is drawn from a U[0, Δ] distribution. Random samples of size N are subsequently selected from the population at regular time intervals Δ. Infection is detected at a given time if a Detectable plant is contained in the sample selected at that time. C. The baseline EDP, expressed as a percentage of the total crop population size, as the sample size (N = NC) and sample interval (Δ) vary.