Microbiological Control of Plant Pathogens

This chapter discusses a few aspects of microbiological control of plant pathogens, including its occurrence in nature, the most common microbial groups and the mechanisms involved, with emphasis on its practical implications. Microbiological control of plant diseases can be achieved directly, through inoculation, or indirectly, by changing the conditions prevailing in the plant's environment, and thus the microbiological equilibrium of its ecosystem, or by a combination of both approaches. The chapter presents a few examples demonstrating the control of plant diseases by inoculation. Microorganisms parasitic to plants constitute a tiny fraction of the microflora and microfauna inhabiting the vicinity and surfaces of plant organs. Disease severity is greatly increased when the pathogen is reintroduced in its pre-sterilized infection site, indicating that the saprophytic microorganisms inhabiting the surfaces of plant organs may serve as a biological buffer zone, preventing the pathogen from infecting its host. Selective pathogen suppression can be achieved by the use of specific chemicals, such as fungicides, which are applied at relatively low dosages. Soil treatment with fumigants, such as chloropicrin, methyl bromide or formalin, results in eradication of both the pathogen and most of the saprophytic microflora.