ABSTRACT
The term biological control has many different definitions [1]. In this chapter I will use the definition proposed by Baker and Cook [2]: ‘‘Biological control is the reduction of inoculum or disease producing activity of a pathogen accomplished by one or more organisms other than man.’’ This definition is broad enough to encompass classical approaches to biological control that directly influence pathogen populations via antibiosis, parasitism, or predation as well as approaches that afford disease reduction through competition for nutrients or infection niches, induced systemic resistance, altered plant physiology, or use of transgenic strategies. While specific biological controls will be discussed in detail, it is important to understand that resident soil microflora and fauna are responsible for much of the disease reduction attributed to crop rotation or incorporation of organic amendments. The specific role(s) of individuals or communities of these organisms in affecting either pathogen populations or disease severity is largely unknown.
