A Percolation-Based Risk Index for Pathogen Invasion
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A Percolation-Based Risk Index for Pathogen Invasion

A Percolation-Based Risk Index for Pathogen Invasion: Application to Soilborne Disease in Propagation Systems

Propagation systems for seedling growth play a major role in agriculture, and in notable cases (such as organic systems), are under constant threat from soil- and seed-borne fungal plant pathogens such as Rhizoctonia solani or Pythium spp. Yet, to date little is known that links the risk of disease invasion to the host density, which is an agronomic characteristic that can be readily controlled. An original feature of the work performed by IGEPP researchers consisted in introducing a percolation framework to analyze the link.

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An experimental design was set up to study the spread of the ubiquitous fungus R. solani in replicated propagation systems with different planting densities. A percolation-based epidemiological model was then fitted to the data using Bayesian inference methods. The estimated probability of pathogen transmission between infected and susceptible plants was used to calculate the risk of invasion. By comparing the transmission probability and the risk values obtained for different planting densities, evidence was given of a nonlinear relationship between disease invasion and the inter-plant spacing, hence the existence of a spatial threshold for epidemic invasion.

As risk measure plays a key role in the evaluation and adoption of disease control strategies, we posit that this new risk assessment method could be useful in the decision process for disease management, combined with other economically relevant factors (e.g., lower densities imply a reduction in output, but can also improve vigor and quality of healthy seedlings).

This work has been performed in collaboration with researchers from the Department of Plant Sciences, University of Cambridge, and supported by the French Research Agency (ANR) through funding of the SYSBIOTEL project.

Poggi S., Neri F.M., Deytieux V., Bates A., Otten W., Gilligan C.A. & Bailey D.J. (2013). Percolation-Based Risk Index for Pathogen Invasion: Application to Soilborne Disease in Propagation Systems. Phytopathology, 103(10): 1012-1019. http://dx.doi.org/10.1094/phyto-02-13-0033-r

Modification date: 06 February 2023 | Publication date: 03 October 2013 | By: Igepp