ESM 1a Sensitivity analysis for the change in accuracy of the rule of thumb with
multiplicative percent changes in the transmission rate (). The change in 95th percentile
discovery-prevalence for the approximation rule of thumb (closed circles) and HLB
simulation model (open circles), and their quotient, for a sample size N of 10 and sampling
interval Δ of 25 days (A and B), 50 days (C and D), 75 days (E and F) and 100 days (G and H).
HLB age class 6-10 is used to provide the default parameter values from which the
percentage change is referenced. Page 2.
ESM 1b Sensitivity analysis for the change in accuracy of the rule of thumb with
multiplicative percent changes in the dispersal scale (1/). The change in 95th percentile
discovery-prevalence for the approximation rule of thumb (closed circles) and HLB
simulation model (open circles), and their quotient, for a sample size N of 10 and sampling
interval Δ of 25 days (A and B), 50 days (C and D), 75 days (E and F) and 100 days (G and H).
HLB age class 6-10 is used to provide the default parameter values from which the
percentage change is referenced. Page 1.
ESM 1c The change in the sampling interval Δ (days) required to achieve a discoveryprevalence of 0.001 (0.1%) (left-hand panel) and 0.005 (0.5%) (right-hand panel) for
changing total population size and for the different age classes. The sample size N is fixed at
10% and thus changes with total population size accordingly. Page 3.
ESM 1d Additional discussion of results in the context of the assumption of exponential
increase made by the rule of thumb approximation.
ESM 1e Probability distributions for discovery-prevalence for the different HLB planting age
classes. The mean (equation 6) and 95th percentile discovery-prevalences are shown for
the rule of thumb (solid and open circles respectively) and the HLB simulation model
(dashed and dotted lines respectively). The sample size N is 50 trees and sample interval Δ
50 days. The different planting age classes are: age 0-2 years (A), 3-5 years (B), 6-10 years (C)
and >10 years (D). Discovery-prevalence q* is the fraction of the population infected. Page
5.
ESM 2a The citrus canker Miami study sites. The upper left panel shows the general location
of the sites in Florida. The right hand panel shows the location of residential citrus trees
(green dots) in each site are citrus trees in residential properties. Black dots denote the
location of all infected trees at the end of the observation period. The background is a
satellite image of the area. The four study sites are the 4 discrete areas of green host trees
from north to south and are named as Miami 1, Miami 2, Miami 3 and Miami 4 respectively.
Miami 4 is enlarged on the lower left hand panel to illustrate the finer scale spatial pattern
of the citrus trees and terminal distribution of the epidemic. Page 1.
ESM 2b The change with time in epidemic prevalence for each of the Miami Study sites. The
red line denotes the observed epidemic progress curves (change in proportion of infected
trees with time) and the black line denotes the logistic fit to the curves as reported in the
main manuscript. Page 2.
ESM 2c Probability distributions for discovery-prevalence for the different Miami study sites.
The mean and 95th percentile discovery-prevalences are shown for the rule of thumb (solid
and open circles respectively) and the citrus canker Miami dataset (dashed and dotted lines
respectively). The sample size 𝑁 is 50 trees and sample interval 𝛥 50 days. The study sites
are Miami 1 (A), Miami 2 (B), Miami 3 (C) and Miami 4 (D). Discovery-prevalence q* is the
fraction of the population infected. Page 3.
ESM 2d The change in discovery-prevalence with sample size, N. Shown is the rule-ofthumb (mean discovery-prevalence) (equation 6) from the approximation equation (grey
triangle) and its 90% confidence interval (5th and 95th percentiles), and the mean discoveryprevalence calculated from the citrus canker Miami data using simple random sampling
(red dots) and stratified-random sampling (blue dots). Shown are results for the study sites
Miami 1 (A,B), Miami 2 (C,D), Miami 3 (E,F) and Miami 4 (G-H) and for a sampling interval Δ
of 25 days (A, C, E, G) and 50 days (B, D, F, H). Note that the difference in y-scale in plots A,
C, E, G and B, D, F, H. Discovery-prevalence q* is the fraction of the population infected.
Page 4.
ESM 2e The change in the sampling interval Δ (days) required to achieve a discoveryprevalence of 0.001 (0.1%) (left-hand panel) and 0.005 (0.5%) (right-hand panel) for
changing total population size for each of the Miami sites. The sample size N is fixed at 10%
and thus changes with total population size accordingly. Page 5.
ESM 3 A single realisation of the HLB epidemic simulation model for Age class 6-10. Left
hand panel show citrus planting with healthy trees (green) and infected trees (increasing
severity as white to red intensity). The corresponding upper and lower right-hand panels
show the corresponding change in incidence and severity respectively with time.