LAUSR

Soilborne pathogens cause severe diseases in many crops. They have common features based on their close connection with the soil, which has a strong influence on their survival and capacity to cause disease. The latter stems from interactions between the pathogen and the host, which both in turn interacts with the biotic and abiotic components of the environment. Soilborne pathogens produce resting structures which, in the absence of a host, are inactive, and are therefore protected from the soil's hostile activities due to fungistasis. However, in the presence of root exudates of a susceptible host in the rhizosphere, or an adequate nutrient source, they germinate and infect the plant, pending suitable conditions. In addition, soilborne pathogens may colonize the roots of plants that are not their major host, without inducing visible symptoms. Soilborne pathogens have many mechanisms for their spatial dispersal, e.g., through infected propagation material. Basic management strategy involves disruption of one or more of the disease components, at any stage of disease development, to achieve an economic reduction in disease with minimal disturbance to the environment. This is achieved by chemical, physical, biological, cultural, physiological and genetic approaches, using soil disinfestation (fumigation, soil solarization, biofumigation, anaerobic soil disinfestation), biocontrol, organic amendments, resistant cultivars and grafting, fungicides, cultural practices, induced resistance and others. These should be carried out in the framework of integrated pestmanagement programs. Many challenges remain. We need to study the gap between promising results obtained under controlled conditions and the modest results obtained under realistic ones. A better understanding of the mechanisms and modes of action of the involved processes should provide new tools for disease management.