Multi-scale modeling of potato late blight epidemics

P. Skelsey

Research output: Thesisinternal PhD, WU

Abstract

Keywords: Solanum, invasion, Gaussian plume model, functional connectivity, landscape design

Proper landscape-scale deployment of disease resistant genotypes of agricultural crop species could
make those crops less vulnerable to invasion by resistance breaking genotypes. Here we develop a
multi-scale, spatio-temporal model of the potato late blight pathosystem (Phytophthora infestans -
Solanum tuberosum) to investigate spatial strategies for the deployment of host resistance. The
model comprises a landscape generator, a potato late blight model, and a suite of aerobiological
models, including an atmospheric dispersion model. Spatial phenomena are solved using Fast Fourier
transforms.
Increasing the number of host genotypes caused the greatest reduction in epidemic extent,
followed by reduction of the proportion of potato in the landscape, lowering the clustering of host
fields, and reducing the size of host fields. Simulation results showed that spatial spread through
short-distance “island hopping” is not a prerequisite for P. infestans invasions, and it appeared not
possible to generate host free zones at the landscape level that were large enough to provide
worthwhile levels of resilience against disease invasion from one host area to another. Deployment
of host resistance in genotype mixtures had a large effect on disease invasion. A new functional
connectivity parameter, characterizing the probability of successful infection following spore
dispersal, proved to be useful in interpreting these results.
Variation in simulation results revealed the importance of using an atmospheric dispersion
model for dispersal, with large weather data sets, and many random landscape iterations. The
specific coincidence in time and space between weather conditions and the geographic locations of
source and target sites defined true landscape connectivity and determined model results regarding
inoculum exchange between fields.
Given the apparent capacity of P. infestans for long distance transport of viable inoculum, it can
be concluded that spatial resistance deployment strategies that center on the creation of spatial
barriers to disease at scales up to several kilometers may not be effective in mitigating invasions of
virulent pathogen strains. Strategies that induce finer-grained spatial and genotypic heterogeneities
in host populations are more limiting to epidemic spread. Genotype mixing was an effective option
for generating agricultural landscapes that are comparatively resilient to disease invasion.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Holtslag, Bert, Promotor
  • van der Werf, Wopke, Co-promotor
  • Kessel, Geert Jan, Co-promotor
  • Rossing, Walter, Co-promotor
Award date2 Sep 2008
Place of PublicationS.l.
Print ISBNs9789085049418
Publication statusPublished - 2008

Keywords

  • phytophthora infestans
  • solanum tuberosum
  • epidemics
  • disease models
  • spore dispersal
  • virulence
  • epidemiology
  • integrated pest management
  • host pathogen interactions

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