ABSTRACT
This chapter describes the methods used for biological control through introduced antagonists. It discusses the principles of biological control. Biological control of plant diseases is slow, gives few quick profits, but can be long lasting, inexpensive and harmless to life. Changing pH, soil moisture, temperature, texture and nutrient status in favor of pathogen antagonists can reduce disease severity. Cell-free culture filtrates of organisms that inhibit growth of a test pathogen in an agar medium can be tested for antibiotic production. The selection of a suitable assay medium that supports growth of the test pathogen and will not inactivate or mask the activity of the antibiotic is essential. The value of amoebae in biological control of plant pathogens is not established, but they play an important role in the ecology of soilborne plant pathogens. The chapter also describes a few methods of screening soils and isolation of mycophagous amoebae.
