Developing smarter host mixtures to control plant disease

Abstract

Adaptation of plant pathogens to disease control measures (both chemical and genetic) is facilitated by the genetic uniformity underlying modern agroecosystems. One path to sustainable disease control lies in increasing genetic diversity at the field scale by using genetically diverse host mixtures. In this study, a robust population dynamics approach was used to model how host mixtures could improve disease control. It was found that when pathogens exhibit host specialization, the overall disease severity decreases with the number of components in the mixture; this finding makes it possible to determine an optimal number of components to use. In a simple case, where two host varieties are exposed to two host-specialized pathogen species or strains, quantitative criteria for optimal mixing ratios are determined. Using these model outcomes, ways to optimize the use of host mixtures to decrease disease in agroecosystems are proposed.