Strategies of soilborne plant pathogenic fungi in relation to disease suppression

Abstract

The purpose of classifying pathogens based on ecological traits is that certain generalizations can be made beyond the specific or “model” pathogen that has been investigated. Usually this is done at the taxonomic level of species, but infraspecific variation in ecological traits frustrates such classifications. Moreover, shifts in traits can take place during the life cycle of the pathogen, and plant-mediated rhizosphere effects affect the ecological traits of pathogens. It is therefore useful to separate management of the pathogen, leading to pathogen suppression, from management of the disease, which is essentially plant-mediated. Both approaches may act via specific or general suppression, although the latter mainly acts in the bulk soil. An ecological classification of a given pathogen isolate needs to take into account host range, host sensitivity, host species (in relation to systemically acquired resistance (SAR)/induced systemic resistance (ISR) and host-affected rhizosphere communities), sensitivity to fungistasis, ability to compete for organic matter, sensitivity to specific disease suppression and survival capability. We conclude that generalization at the species level is imprecise and often misleading.