Biological Control of Microbial Plant Pathogens in Alternative Sources of Infection

Abstract

Microbial plant pathogens causing crop diseases are able to survive by infecting different weed species, self-sown volunteers and plants growing from asexually propagated infected tubers left in the field. In the case of plant viruses, the vectors form an important source of infection, especially for propagative viruses that are able to multiply in the vectors and pass on to the next generation. Biological control of pathogen inoculum present in alternative sources has been considered as a feasible approach to reduce the spread of the disease to the primary hosts, the crops. Fungal and bacterial biocontrol agents have been evaluated for their efficacy in suppressing the development of various weed plants that may serve as alternative sources of infection in the absence of primary host plants. Some of the fungal pathogens have been identified as mycoherbicides and they have been developed as commercial products for wider application. Entomopathogenic fungi effective against important groups of insects functioning as vectors of viruses have been identified. Extensive evaluation of their potential against plant virus vectors has to be undertaken under field conditions.