Compost teas: alternative approaches to the biological control of plant diseases.

Abstract

This review focuses on the induction of uncharacterized microbial communities through the use of compost teas. Due to the scarcity of peer-reviewed literature on this topic, this review will incorporate non-peer-reviewed literature and popular press accounts to indicate areas that show promise and are in need of scientific investigation. It is speculated that achieving consistent disease suppression with compost tea applications will require: modification of compost tea production steps (e.g. nutrient amendments) to ensure the growth of specific groups of microbes; the incorporation of spray adjuvants to enhance attachment and survival of microbes in soil or on plant surfaces, and the development of spray equipment that is more suitable to the delivery of living microorganisms. Compost teas represent only one tool in an arsenal of options that can be utilized within an integrated system that incorporates genetic disease resistance, fertility and water management, disease and pest forecasting, and other cultural approaches to enhance plant health.

A study of selected factors affecting efficacy of compost tea against several fungal pathogens of potato

“…; Mahaffee et al . ; Koné et al . ), biotic components have generally been regarded as critical in mediating the mode of action.…”

“…While some reports have highlighted the potential role of abiotic factors, including nutrients in the compost tea (Tang et al 2003) or microbial antibiotics (Al-Dahmani et al 2003;Mahaffee et al 2006;Kon e et al 2010), biotic components have generally been regarded as critical in mediating the mode of action. For example, compost tea efficacy was significantly reduced (Siddiqui et al 2009) or lost (Gea et al 2009) after autoclaving or filtration, suggesting that live micro-organisms in compost teas have a direct effect.…”

Potential of compost tea for suppressing plant diseases.

“…However, there is now considerable scientific evidence, which shows that various types of compost tea and/or compostbased liquid preparations can suppress phytopathogens and plant diseases [4][5][6][7][8][9]. Despite this evidence, the practical application of compost tea for plant disease management has been limited, and the paradigm for plant disease control in modern agriculture of using one active ingredient to target one or multiple pathogens still persists [10]. In most cases, this approach to plant disease control has been translated into a heavy reliance on a single control strategy, which is often the widespread use of synthetic pesticides.…”

“…However, for the most part, research efforts for BCAs have generally followed a similar paradigm to synthetic pesticides, i.e. a single organism is identified and developed for delivery into an agroecosystem [10]. The use of this approach with BCAs has resulted in far less commercial successes [23] than with synthetic pesticides and has developed a reputation for inconsistent plant disease control [24,25].…”

“…Mahaffee and Scheuerell [10] reported that this inconsistency results from the influence of numerous biotic and abiotic factors that affect the ability of the BCA to survive the application process, attach to, grow and reproduce on the plant and inhibit pathogenesis. Moreover, they concluded that the reasons suggested for the inconsistency of BCAs were all related to the inability of a single organism to be 'all things at all times' in an extremely dynamic and harsh environment.…”