Influence of Host Diversity on Development of Epidemics: An Evaluation and Elaboration of Mixture Theory

Research output: Chapter in Book/Report/Conference proceedingAbstract


A spatio-temporal/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.
Original languageEnglish
Title of host publicationProceedings of the 2005 APS Annual Meeting, Austin, Texas, July 30 - August 3, 2005
Place of PublicationAustin, Texas - USA
PublisherThe American Phytopathological Society
Publication statusPublished - 2005
Event2005 APS Annual Meeting - Austin, TX, United States
Duration: 30 Jul 20053 Aug 2005

Publication series

PublisherThe American Phytopathological Society
ISSN (Print)0031-949X
ISSN (Electronic)1943-7684


Conference2005 APS Annual Meeting
Country/TerritoryUnited States
CityAustin, TX


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