Soil‐borne fungal pathogens: scaling‐up from hyphal to colony behaviour and the probability of disease transmission

Abstract

Summary The transmission of many fungal soil‐borne plant pathogens is mediated by the growth of the fungal colony from an infectious to a susceptible host plant. Here we develop a mechanistic, spatially‐explicit, mathematical model that allows us to scale from hyphal growth and branching, through colony growth to analyse and predict the transmission of infection. We derive approximate analytical solutions for colony behaviour. These are used to drive equations for the evolution of the pathozone dynamics which characterize the ability of pathogens to infect hosts from various distances in soil. It is possible to scale up from hyphal behaviour to the scale of transmission of infection. We identify two key periods in pathozone dynamics: an initial period during which no transmission of infection occurs, followed by the advection of the pathozone profile away from the infectious host at an approximately constant rate. The models enable the prediction of probability of transmission of infection from hyphal‐scale behaviour. However, a coherent theory scaling from hyphal dynamics through colony behaviour to properties of the whole epidemic awaits further theoretical and experimental work.