APS Homepage

Oral: Dispersal at Multiple Scales: A Key to Outbreak of Disease Epidemics


Introduction: The importance of dispersal in botanical epidemics
L. MADDEN (1) (1) Ohio State University, U.S.A.

View Presentation

The spatio-temporal dynamics of plant diseases depend on dispersal, the movement of inoculum from where it is produced to where it is deposited. There is a long history of dispersal research by epidemiologists, with pioneering contributions by Philip Gregory, James Hirst, and others in previous generations, and by the current symposium speakers in today’s scientific generation. Dispersal is a physical process (spore removal, transport, and deposition) superimposed on a biological process (spore production, survival of transported spores, infection efficiency of deposited inoculum, latent and infectious periods). Moreover, dispersal requires observations at multiple locations, by definition, and the locations may be (greatly) separated in time and space. These conditions result in huge challenges in conducting research, and most plant pathologists have not taken the challenge. Yet, one clearly needs to account for dispersal in empirical research and in modeling. A theoretical epidemic model will be used to show the general influence of dispersal on temporal disease increase and the rate of disease spread in space. The relevant model component is the contact distribution, the probability of a spore originating at one location (say, where it was produced) coming in contact with a host individual at another location s distances units away, where it may cause infection. Physics is needed to fully define this contact distribution.