Influence of Host Diversity on Development of Epidemics: An Evaluation and Elaboration of Mixture Theory
Document Type
Article
Journal/Book Title/Conference
Phytopathology
Volume
95
Publication Date
2005
First Page
328
Last Page
338
Abstract
A spatiotemporal/integro-difference equation model was developed and utilized to study the progress of epidemics in spatially heterogeneous mixtures of susceptible and resistant host plants. The effects of different scales and patterns of host genotypes on the development of focal and general epidemics were investigated using potato late blight as a case study. Two different radial Laplace kernels and a two-dimensional Gaussian kernel were used for modeling the dispersal of spores. An analytical expression for the apparent infection rate, r, in general epidemics was tested by comparison with dynamic simulations. A genotype connectivity parameter, q, was introduced into the formula for r. This parameter quantifies the probability of pathogen inoculum produced on a certain host genotype unit reaching the same or another unit of the same genotype. The analytical expression for the apparent infection rate provided accurate predictions of realized r in the simulations of general epidemics. The relationship between r and the radial velocity of focus expansion, c, in focal epidemics, was linear in accordance with theory for homogeneous genotype mixtures. The findings suggest that genotype mixtures that are effective in reducing general epidemics of Phytophthora infestans will likewise curtail focal epidemics and vice versa.
Recommended Citation
P. Skelsey, W.A.H. Rossing, G.J.T. Kessel, J. Powell, and W. van der Werf. 2005. “Influence of Host Diversity on Development of Epidemics: An Evaluation and Elaboration of Mixture Theory,” Phytopathology 95:328-338.
