Data from: Invasiveness of plant pathogens depends on the spatial scale of host distribution

Plant diseases often cause serious yield losses in agriculture. A
pathogen’s invasiveness can be quantified by the basic reproductive
number, R0. Since pathogen transmission between host plants depends on the
spatial separation between them, R0 is strongly influenced by the spatial
scale of the host distribution.We present a proof of principle of a novel
approach to estimate the basic reproductive number, R0, of plant pathogens
as a function of the size of a field planted with crops and its aspect
ratio. This general approach is based on a spatially explicit population
dynamical model. The basic reproductive number was found to increase with
the field size at small field sizes and to saturate to a constant value at
large field sizes. It reaches a maximum in square fields and decreases as
the field becomes elongated. This pattern appears to be quite general: it
holds for dispersal kernels that decrease exponentially or faster, as well
as for fat-tailed dispersal kernels that decrease slower than exponential
(i.e., power-law kernels).We used this approach to estimate R0 in wheat
stripe rust (an important disease caused by Puccinia striiformis), where
we inferred both the transmission rates and the dispersal kernels from the
measurements of disease gradients. For the two largest datasets, we
estimated R0 of P. striiformis in the limit of large fields to be of the
order of 30. We found that the spatial extent over which R0 changes
strongly is quite fine-scaled (about 30 m of the linear extension of the
field). Our results indicate that in order to optimize the spatial scale
of deployment of fungicides or host resistances, the adjustments should be
made at a fine spatial scale. We also demonstrated how the knowledge of
the spatial dependence of R0 can improve recommendations with regard to
fungicide treatment.