Can epidemic control be achieved by altering landscape connectivity in agricultural systems

Few investigations on host diversification at the landscape scale to control plant disease in agricultural systems are available in the literature. At this scale, landscape connectivity measures how the landscape structure facilitates or impedes the disease spread among host patches. We developed a simulation model, giving a particular attention to the representation of the landscape structures, and we characterized the landscape connectivity by the proportion and the aggregation level of the host varieties, the ability for the pathogen to develop on each host and its ability to disperse. The pathogen dynamics was represented by a matrix population model designed for a generic air-borne foliar disease. This framework was used to establish a detailed assessment of the influence of each landscape connectivity variable on the pathogen population dynamics. When deploying a host with complete resistance to the pathogen along with a susceptible host, mixed landscapes were always found to be more efficient to hamper the disease spread. However, when using a quantitatively resistant host, aggregating the hosts in different regions could result in a better control of the pathogen spread, depending on the proportion and level of resistance of the resistant host and according to a source–sink dynamics between the two hosts. The ability of the pathogen to disperse did not change the results from a qualitative point of view. By accounting explicitly for the landscape features, our approach can be used to guide further data analysis or to evaluate the effectiveness of control strategies designed at the landscape scale.