Status and future of compost tea in horticulture

Crop protectants are applied to crops to prevent loss of yield and pre-harvest spoilage by plant pathogens. Contemporary disease management focuses on the integration of cultural and biological controls to reduce or eliminate the need for synthetic chemicals. Compost tea is a watery extract of microorganisms and nutrients from compost for application to the soil or crop canopy. It is a type of biological control that has potential to suppress a broad range of plant pathogens. We provide a framework for evaluating the efficacy and safety of compost teas for management of fruit and foliar diseases in horticultural crops. Mechanisms for integrated disease management are discussed in the context of mode of action, batch-to-batch variation in tea quality, spray timing and technique, and variation in disease suppression among sites and growing seasons. Future research is proposed to further identify the role of compost teas in sustaining crop yields, produce quality and rural livelihoods.