Enhancing soil suppressiveness using compost and compost tea represents an alternative biocontrol approach to the conventional paradigm of plant disease control, one that is based on the use of several microorganisms at the same time to control one or many pathogens rather than the conventional use of one active ingredient or microbial agent to target one or multiple pathogens. Inclusive in this paradigm shift in disease control are (1) mixing of several known types of biocontrol agents (BCAs) with diverse modes of action or that colonise different ecological niches (Siddiqui and Shaukat 2002),(2) the enhancement of resident populations existing on or around the plant (Mazzola 2007), and (3) the introduction of partially or uncharacterised microbial communities usually with no known activity (Litterick et al. 2004). Compost and compost tea used as biocontrol agents fall under the latter group of strategies in this paradigm shift. Although research on compost and compost tea has been conducted for decades, there is now increasing interest in their possible role in developing suppressive soils and managing plant diseases. This interest has primarily arisen due to increasing demand for organically produced foods (Dimitri and Greene 2000) and concerns by the public over the use and potential negative impacts of synthetic pesticides on human health and environment.

St. Martin (2013) argued that the theoretical basis for the effectiveness of compost and compost tea in suppressing phytopathogens is their ability to alter the microbial profile and activity of the rhizosphere and/or soil as a whole. However, it is highly debatable whether compost tea alters the microbiota of the